JUN 1 1984 - DSpace@MIT
The Audio-Graphical Interface
to a
Personal Integrated Telecommunications System
Barry Michael Arons
B.S. Civil Engineering
Massachusetts Institute of Technology
Submitted to the Department of Architecture
in partial fulfillment of the requirements for the degree of
Master of Science in Visual Studies
at the
Massachusetts Institute of Technology
June 1984
copyright (c) Massachusetts Institute of Technology 1984
Signature of author....................
Michael Arons
Department of Architecture
May 11, 1984
Certified by . . . . . . . . . . ............
Professor ndrew Lippman
Associate Pr of essor of Media Technology
Thesis Supervisor
Accepted by .
Professor Nicholas Negroponte
Chairman, Departmental Committee for Graduate Students
JUN 1 1984
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Thank you.
The Audio-Graphical Interface
to a
Personal Integrated Telecommunications System
Barry Michael Arons
Submitted to the Department of Architecture on May 11, 1984
in partial fulfillment of the requirements for the degree of
Master of Science in Visual Studies.
The telephone is proposed as an environment for exploring conversational
computer systems. A personal communications system is developed which
supports multi-modal access to multi-media mail. It is a testbed for developing
novel methods of interactive information retrieval that are as intuitive and useful
as the spoken word.
A personalized telecommunications management system that handles both
voice and electronic mail messages through a unified user interface is described.
Incoming voice messages are gathered via a conversational answering machine.
Known callers are identified with a speech recognition unit so they can receive
personal outgoing recordings. The system's owner accesses messages over the
telephone by voice using natural language queries, or with the telephone keypad.
Electronic mail messages and system status are transmitted by a text-to-speech
synthesizer. Local access is provided by a touch sensitiveoscreen and color
raster display. Text and digitized voice messages are randomly accessible
through graphical ideograms. A Rolodex-style directory permits dialing-by-name
and the creation of outgoing recordings for individuals or mailing lists.
Note: A 3/4 inch color U-matic video cassette accompanies this thesis, it is
five minutes in length, and has an English narrative.
Thesis Supervisor: Andrew B. Lippman
Title: Associate Professor of Media Technology
The work reported herein was supported by a grant from Atari, Inc. and NTT,
the Nippon Telegraph and Telephone Company.
Table of Contents
Introduction: The Personal Telecommunications System
Chapter One: Telephone Perspective
1.1 A Brief History of the Telephone
1.2 Speech Recognition
1.2.1 Bell Laboratories
1.2.2 Nippon Electric Company
1.2.3 Nippon Telegraph and Telephone
1.2.4 Verbex
1.2.5 Votan
1.3 Voice Dialing
1.3.1 Bell Laboratories Repertory Dialer
1.3.2 Ericsson Voice Controlled Intercom
1.3.3 ITT Experimental Voice Dialing PABX
1.3.4 Audec Command Dialer
1.4 Speech Synthesizers
1.4.1 Federal Screw Works
1.4.2 Digital Equipment Corporation
1.4.3 Speech Plus
1.5 Voice Storage and Forwarding
1.5.1 Bell Custom Calling Services
1.5.2 VMX Voice Message Exchange
1.5.3 IBM Audio Distribution System
1.5.4 PABX Based Voice Storage Systems
1.6 Integrated Telecommunication Workstations
1.6.1 Bell Experimental Teleterminals
1.6.2 Zaisan Voice/Data Workstation
1.6.3 Xerox Etherphone
1.6.4 Telrad Touchscreen Terminal
1.6.5 French Telecommunications Videophone
Chapter Two: The Phone Slave
2.1 Computing Environment
2.1.1 Sound System
2.1.2 Voice Synthesizer
2.1.3 Speech Recognizer
2.1.4 Telephone Interface
2.1.5 Graphical Interface
2.2 Voice Reading of Electronic Mail
2.3 The Interactive Answering Machine
Chapter Three: The Personal Integrated Telecommunications
Design Considerations
Remote Access
Graphical Access
Software Design
Multi-modal Input Interface
Chapter Four: Discussion
. 4-
In memory of my mother and father.
Introduction: The Personal Telecommunications System
But a major question remains: will these terminals be
easy to use? Will these electronic interfaces between
humans and computers be compatible with human
beings as well as computers? Although humancomputer interfaces are becoming "friendlier," the
potential for improving their usability is enormous. The
ideal interface should be usable immediately by people
approaching it for the first time, or by those who use
only occasionally. It should allow people to tap the rich
resources of electronic information technology with a
minimum of effort. [Klapman 82]
thesis describes the
interface for
telecommunications system developed at the Architecture Machine Group. The
system owner's methods of interaction and access are explored and developed.
The system is personalized and integrated in that a personal computer becomes
one's total telecommunications manager, handling both incoming and outgoing
communications of various types. The computer acts as its owner's telephone
directory, mail box, and personal secretary. The machine recognizes its owner
and his acquaintances, delivering specialized greetings and messages to each. It
is a system which may be used without realizing that you are conversing with a
machine; it is not necessary to know anything about computers before you use it.
Two common forms of inter-personal communication, voice and text, are
merged. The methods of access and presentation are identical; the differences
between types of messages are made transparent.
Voice messages,
conventionally recorded sequentially or transcribed, are interactively gathered
during a dialogue with the computer in which the maximum amount of relevant
information is interchanged. Text messages, in the form of electronic mail, are
similarly collected, sorted, and distributed. The owner no longer has to obtain his
messages from different sources, waste time playing telephone tag, or worry
about missing an important call. The owner may call in, hear a message from Mr.
X, then create a personalized outgoing recording for Mr. X, making a dialogue
possible even though the parties never speak to each other directly.
Access is multi-modal: by voice, Touch-Tones, or touch sensitive screen.
Each method provides equal capabilities, they may be used individually or in
concert. The primary remote interface is by voice over the existing switched
telephone network. The owner makes verbal requests and is similarly answered
by voice; speech either previously recorded by a human or generated on-the-fly
with a text-to-speech synthesizer. At home or office the owner can interact with a
color raster display outfitted with a touch screen. Touch sensitive ideograms in
various screen images enable the viewing of messages, creation of outgoing
recordings, and dial-by-name capabilities.
Speech, to be an effective bidirectional communication medium, must be
intimately tied to the application [Schmandt 82a, Schmandt 82b].
A speech
recognizer or synthesizer is not a black box that simply gets connected between
a human and a computer instead of a keyboard or computer terminal.
Successful approaches can be broadly classified as systemic or
holistic. The solution is not to make speech i/o replace a few buttons
or indicator lamps, but rather to fully integrate speech into the whole
context of communication, i.e. exchange of information, between the
operator and computer. The tools are not so much recognition as
understanding, with the implication of an intelligent system interacting
with an intelligent user. [Schmandt 82b]
While this work is currently embodied in a hypothetical teleterminall, the
underlying principles investigated in this project range far beyond the telephone.
It is anticipated that speech communication with computers will become more
prevalent in the future, and to this end conversational computers must be
1A teleterminal is defined to be a piece of equipment that merges the functionality of a
traditional te/ephone with that of a computer terminal [Bayer 83].
explored. An area where speech is already a natural mode of communication is
the field of telecommunications. People are quite accustomed to speaking into
the mouthpiece of a telephone and receiving verbal replies. This existing link is
used as a means to investigate machines that speak and listen.
Chapter One
Telephone Perspective
The conventions of telephone use are deeply
established. Although people are often annoyed by the
present arrangements, they also tend to be quite
conservative and to resent changes in the system.
[Swinehart 83]
In the most simple terms possible this work can be described as an
intelligent telephone, and this is the context in which the project was developed.
This chapter traces the evolutionary path of the telephone and introduces various
technologies upon which the personal integrated telecommunications system is
A survey of related research and commercially available products is
included to characterize the current state-of-the-art in teleterminals and
interactive voice messaging systems.
1.1 A Brief History of the Telephone
Samuel F. B. Morse completed his first working model of the telegraph in
Morse and Alfred Vail, his financial backer, exchanged the first long
distance telegraph message between Washington and Baltimore in 1844,
President Lincoln received the first transcontinental telegram seventeen years
later. By 1873 the Western Union Company was transmitting more than 90% of
the telegrams in the U.S., over a network consisting of more than 150,000 miles of
wire. The costs for installing and maintaining the wires, poles, and insulators for
the booming telegraphy market were high, and many enterprising individuals
were trying to develop ways to make multiple use of the existing telegraph lines.
Elisha Gray, one of the eventual founders of the Western Electric Company;
Thomas Alva Edison, the inventor of the incandescent lamp and numerous other
-9 -
devices; and Alexander Graham Bell were all attracted to the lucrative possibility
of giving Western Union the ability to multiply its system capacity without adding
more miles of wire.
In 1874 Edison invented the quadruplex telegraph which
allowed two messages to be sent in both directions on a single telegraph wire.
Bell and his assistant, Thomas Watson, were working on a harmonic telegraph
scheme which would permit 30 or 40 messages to be sent simultaneously.
Bell's first telephone.
An accidental discovery in June 1875 excited Bell so much that he stopped
work on the harmonic telegraph and began working almost exclusively on the
transmission of human voice over wires. This work culminated with the invention
of the telephone for which Bell was granted a patent in early 1876. By the fall of
1877 the newly formed Bell Company had over 1000 telephones in operation. In
the following years many legal battles were fought between Bell and the
telegraph giant Western Union. Edison developed and patented many telephone
devices; most notable was his invention of the pressure sensitive carbon
transmitter which amplified the energy extracted from the sound wave and made
the telephone commercially feasible. In late 1879 Western Union admitted the
validity of the Bell patents, and agreed to retire from the telephone business.
In the early days of the telephone, the operator on a manual switchboard
depended upon tone signals, verbal instructions, and lamps associated with
cords for the handling of calls. Subscribers had to verbally transmit the called
number to the operator despite technical advances in the handling of calls.
Operators also informally served as receivers and transmitters of messages for
their customers.
In many small towns they simply jotted down notes and
periodically tried to deliver them. In all but the smallest exchanges, this quickly
became an unbearable task. In self-defense, the operators reverted back to
simply making connections.
In light of this development and the advent of
automated switching, a new method for the storage and distribution of messages
had to be created.
An early manual switchboard.
The rotary dial was introduced around 1895; this event marked a major
technical advance in telephony. The dial, as it rotates back to its stop position,
generates a train of pulses that correspond to the number of the selected digit.
These pulsed digits are used to directly position switches in the associated
central office so that no operator is involved in the connection of a call.
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An early rotary dial telephone.
By the 1930s telephone answering bureaus sprang up; a specialized
operator would answer the phone, and manually transcribe and deliver
messages. In the early 1950s an attempt was made to mechanize the storage and
playback of one-way voice messages through answer-and-record devices on the
customer's premises. Initially these devices were quite expensive and their major
use was limited to providing universal announcements which could be accessed
by many people. These machines proved to be more economical when a single
device was used to store the messages of many people then when they were
used for individual customers.
In recent years telephone answering machines
have become quite common in homes and offices; a dual-cassette system is
generally employed which permits a single announcement to be played to all
calling parties and the sequential recording of a large number of incoming
The higher switching speeds of electronic switching systems brought about
a need for a more rapid and accurate means of dialing.
Touch-Tone dialing,
introduced by the Bell System, uses tones in the voice frequency range to
transmit dialing information to the central office. These dual-tone multifrequency
(DTMF) signals can be transmitted worldwide, extending new services to the
general public.
The telephone monopoly was controlled by the Bell System until 1968 when
the FCC allowed the Carterfone Company to interconnect its mobile radiotelephones to the Bell System. The Carterfone decision, subsequently upheld by
the Supreme Court, broke AT&T's equipment monopoly, allowing other vendors
to enter the telephone market.
In 1982, an agreement was reached between
AT&T and the U.S. Justice Department, that led to the deregulation of the phone
industry and the divestiture of the Bell system in 1984.
communications industry so that new and improved products and services could
become available for consumers more quickly than when the industry was under
the near-total control of a regulated monopoly. The long term effects of the AT&T
breakup are still uncertain, but many advanced telecommunications products
such as those described in this document would not have been possible without
the Carterfone decision.
1.2 Speech Recognition
Although I have not been able to track it down, I have
heard there is a paper about one of the hardest
problems in Artificial Intelligence and Signal
Processing entitled "How to wreck a nice beach."
[Hint: say it aloud.]
Computer Humor, Communications of the ACM, April
People often take their ability to understand speech for granted.
recognition by machines is a very complicated task which may involve signal
processing, pattern matching, and syntactic and semantic constraints [Klatt
77, Reddy 76]. Automatic speech recognition is currently being used in the office
for information entry and retrieval and in industry where jobs require handsbusy/eyes-busy activities.
Speech recognition may both reduce expensive
manpower requirements while substantially increasing the functionality of
computers in such environments.
There are several general classifications of automatic speech recognition
systems including: speaker-dependent vs. speaker-independent, isolated speech
virtual vocabulary [Pathe 83].
connected speech, and limited vs.
recognizers must be trained to a particular word set, for speaker-independent
recognizers speech samples from hundreds of people must be gathered and
The computation necessary for connected speech recognition is
significantly more complex than for isolated word recognition. The task is made
difficult by the dropping of inter-word pauses and the coarticulation of adjacent
words in continuous speech. For example, when spoken quickly in a sentence,
the words "did you" are usually pronounced as "didja".
Although specific speech recognition systems differ in the details of
implementation, all existing systems go through three essential steps in
performing recognition: feature extraction, similarity determination, and response
Feature extraction consists of processing the incoming acoustic signal to
determine the beginning and ending of an utterance, and to yield a set of
features. Less expensive systems base their features on a simple measure of
energy and zero crossing rates. The most common technique is to use the output
of a bandpass filter bank.
A third method bases the feature set on a linear
predictive coding (LPC) analysis of short overlapping segments of the digitized
signal. Commercial systems often use proprietary techniques instead of, or in
combination with these methods.
The features extracted from the speech signal are then compared with
previously stored feature sets or templates to produce a similarity metric. The
features must be time aligned with the templates using a technique such as
dynamic time warping or linear time alignment. Dynamic time warping involves a
nonlinear compression or expansion of the input signal to maximize its similarity
measure against the template.
The exact method of similarity determination
depends upon the feature set used, but may simply be the number of bits in the
input signal that match corresponding bits in the template. Speaker-independent
recognition systems usually contain multiple templates for each vocabulary item,
characterizing variation in a word across speakers and speaking conditions. In
sophisticated speaker-independent systems, the templates may be adapted
automatically to provide better recognition performance as a speaker continues
to use the system.
The system must make a decision as to which template most closely
represents the spoken input. Most recognition systems allow the setting of an
absolute threshold; if the highest score doesn't exceed this limit, no recognition
decision will be made. Some systems also provide the option of setting a relative
threshold based on the ratio of the highest and second highest scores. If both
thresholds are exceeded, the utterance is recognized.
Higher level information can also be used to syntactically constrain or
partition the vocabulary. It may, for example, be known that the utterance must
be a one or zero, as in the second digit position of an area code. To speed the
similarity determination process, the pattern matching may only take place
between these two templates.
Similarly, the response decision may also be
limited by this knowledge.
In fact a straightforward digit recognition task with only 10 words
total (0 through 9), but with each word equally likely, is far more difficult
then most tasks that have actually been tested using laboratory ASR
systems with total vocabularies of up to 1000 words...Performance
error rates often increase by a factor of 3 to 10 when a laboratory
system, tested experimentally on 100, 200, or more voices, moves into a
genuine, commercial, field operation. [Baker 81]
Speech recognition over the phone is aggravated by several factors: 1)
human speech ranges in frequency from approximately 100-8000 Hz, while the
telephone is band is limited to 300-3000 Hz, therefore some information carrying
parts of speech spectrum are lost, 2) frequency characteristics vary depending
upon the telephone line and telephone set being used, 3) a carbon granule
telephone transmitter produces nonlinear distortion (more distortion with higher
input level), 4) input sound levels may vary over a broad range, and 5) many types
of line and room noise, with different frequency characteristics, overlap the input
speech signal.
1.2.1 Bell Laboratories
Bell Laboratories produced an isolated word recognition system based on
equally spaced frames of LPC coefficients [Itakura 75]. This recognizer was used
over dial-up phone lines for several experiments dealing with a simple airline
information and reservation system. An 84 word vocabulary was initially used in a
question and answer dialogue between the caller and the computer. This type of
dialogue often resulted in a long series of questions in order to completely
specify a request.
The vocabulary was expanded to 127 words, including many auxiliary and
function type words, so that reasonably natural English sentences could be
The effects of syntactic constraints on this finite-state grammar (144
states, 450 transitions, and 6x10 9 possible sentences) were investigated through
a computer simulation [Levinson 78a] and an experiment [Levinson 78b]. The
simulation consisted of generating 1,000 sentences with an average length of
10.3 words. An assumed word error rate of 10% was reduced to 0.2% by the
syntactic constraints of the task language. In the experiment, speakers prompted
by a computer terminal spoke sentences containing an average of 8.7 isolated
words. Recognition was carried out off-line; the best five word candidates from
the acoustic recognizer were input to the syntax analyzer. As indicated in the
computer simulation, the syntactic analysis had a powerful correcting influence
on acoustic word errors. The word error rate was reduced from 11.7% to only
0.4% and the overall sentence error rate was 3.9%.
A third level, in the form of a semantic processor [Levinson 80], was added
to the existing recognizer/semantic analysis system. An audio response system
was controlled by this processor so that a natural language conversation could
be held with the machine. With one set of test sentences, 6 of 21 sentences were
corrected by the semantic processor without intervention by the user.
remaining 15 sentences caused the system to responded with "What did you
say?", the error was corrected by the user on his next input sentence.
In no case was communication seriously disrupted.
phenomenon has a profound effect on the user of the system. His
attention is drawn away from speech recognition accuracy and sharply
focused on the exchange of information between himself and the
machine. This points very strongly to the conclusion that progress in
speech recognition can be made by studying it in the context of
communication rather than in a vacuum or as part of a one-way
channel. [Levinson 80]
An automatic directory assistance system that permits users to spell out the
last name and initials of the desired party with Touch-Tones has been available
for the 18,000 entry Bell Laboratories telephone directory since 1976 [Rabiner
Multiple matches occur approximately 25% of the time due to identically
spelled names (only the first six letters are used) and ambiguities arising from the
multiple letters assigned to each button on the keypad.
These conflicts are
resolved by using a voice-response system which asks the caller to supply
additional information. Related work has shown that carefully worded prompts
can elicit isolated speech even from first time users [Holmgren 83].
The previously described isolated word recognizer was used in conjunction
with this database to provide a speaker-dependent [Rosenberg 79], and
subsequently a speaker-independent [Rosenberg 80], directory system.
spoken alphabet is a notoriously poor vocabulary for a word recognizer; large
groups of utterances within the vocabulary are easily confused because they
have minimal acoustic differences (e.g.
the A-J-K and B-D...
individual letter error rate of approximately 20% was reduced to 4% for the entire
name in both the dependent and independent training cases by the constraints
imposed by the spellings of the names.
1.2.2 Nippon Electric Company
Nippon Electric Company (NEC) has produced several speech recognition
products ranging upward in complexity from a single board for a personal
computer to the NEC SR-1000.
The SR-1000 series speaker-independent
isolated word recognizers are designed to be used over the phone line as part of
an integrated voice recognition and voice response (V&V) system [NEC 82]. The
SR-1201 can be used to recognize ten numerals and six functional words (e.g.
yes, no, cancel) when a push-button telephone is not available 2 .
Each V&V system can be connected to as many as 128 telephones. To use
the recognition units efficiently, they are time-shared by dynamically connecting
them to a telephone line for each input word according to instruction of the
system controller. This system has been used in a banking application allowing
customers to obtain transaction information from any telephone.
2Over 90% of the phones in Japan still use rotary dials.
1.2.3 Nippon Telegraph and Telephone
Nippon Telegraph
and Telephone (NTT)
has developed a speaker-
independent recognition unit specifically for telephone line use [Ishii 82]. The
design of the system was based on an analysis of a large amount of speech data
gathered from many speakers over various telephones and lines. The unit has 32
input channels and a vocabulary of 16 words. The speech detection threshold is
adaptively determined by sampling the background noise on the line. Detailed
recognition results and second and third guesses with confidence values, can be
transmitted to allow the host to perform higher level processing. At any stage of a
recognition sequence the accepted words can be limited to a subset of the given
1.2.4 Verbex
The Verbex Model 1800 speaker-independent isolated word recognizer is
designed to be used over the phone. A 32-bit array processor supports eight
in real-time.
channels of simultaneous recognition
Some machines
commercial use handle over 4000 calls per day. The model 1800 dynamically
adapts to noise and to each speaker's voice during the course of an interaction
(transparent training).
1.2.5 Votan
Votan produces a series of modular voice products including recognizers
tailored for the telephone bandwidth, and
voice response and speaker
verification units. A new system based around a board for the IBM Personal
Computer features a speaker-dependent word recognizer with high noise
immunity and a voice response and storage option. An inexpensive speakerindependent recognizer tailored for phone line use is expected soon.
1.3 Voice Dialing
To converse with a computer in a natural manner it
must, as a minimum, be able to speak, listen and
understand conversational English. [Bergland 82a]
A seemingly natural application of speech recognition is in the area of
automated dialing.
Several experimental and production automatic dialing
systems based on speech recognition have been built on the premise that it is
generally easier to remember a person's name than his telephone number.
1.3.1 Bell Laboratories Repertory Dialer
Bell Labs developed a speaker-dependent dialing system with a vocabulary
of the ten digits, seven commands (e.g.
hangup, error) and a list of names
[Rabiner 80]. Once trained, it could dial the telephone number corresponding to
any name in the repertory, or dial a 4-digit extension when spoken as a string of
isolated digits.
All communication between the user and the system is by voice; there is no
visual display needed to train or operate the system. A digitized voice response
system is used to provide feedback and training cues. If the speech analyzer
detects any recording problems (e.g. level too low), a request is made to repeat
the word. The recognizer only responds to isolated words, so the user may hold
a conversation while the dialer is operating.
The system will not be triggered
unless one of the command words, spoken in isolation, has two distance scores
within prescribed limits. The vocabulary is partitioned such that at any time the
recognizer must choose among only a subset of the candidates. Due to the tight
recognition constraints, no recognition errors and only a small number of
requests for repeats occurred in over 4500 trials for six speakers.
1.3.2 Ericsson Voice Controlled Intercom
A speaker-independent voice dialed intercom system developed at LM
Ericsson Telematerial AB [Lundin 83] permitted access to a list of 30 people
without having to individually train each user.
Pushing the 9 button on the
keypad lit an LED indicating that the recognition unit was ready and that the user
had ten seconds to speak an utterance. A tone indicated recognition processing
after the name was pronounced, an audio response system confirmed the
recognized name. The facility was generally found useful, but the recognition
accuracy and response time were too low and the training procedure too
involved for commercial applicability.
A new speaker-dependent device was developed which eliminated the
speaker-independent training
the effects of varying
acoustical environments, and permitted each user to have a personalized
directory. This work led to the manufacture of a commercial product containing a
Motorola MC68000 microprocessor and a NEC 7720 digital signal processing
Each person can create his own directory by entering the desired
extension number and training the name five times.
1.3.3 ITT Experimental Voice Dialing PABX
A private automatic branch exchange (PABX) is often equipped with
features such as call forwarding and call transfer. These utilities, however, are
often not used because the sequences of keystrokes are difficult to memorize.
ITT developed a system in which a PABX is tied to a speaker-independent
recognizer and speech synthesizer [Mulla 84]. In this configuration the speech
processors are a shared resource serving many users, and hence can justify
higher cost and performance equipment.
21 -
Sample syntax diagram from the ITT PABX.
The system has a well defined syntax and rather limited vocabulary
permitting the use of syntactic constraints to improve recognition performance.
The aggregate score of an utterance is checked against a threshold which is
based on how disastrous the consequences of taking an incorrect action would
The setting of thresholds has a very strong influence on the user's
perception of the system's performance. With the thresholds set too
low, the number of incorrect actions is large, whereas with the
thresholds set too conservatively, the system gives the impression of
being hard of hearing. [Mulla 84]
1.3.4 Audec Command Dialer
Audec Corporation currently markets a consumer product billed as "the
world's first telephone you dial with your voice." In addition to automatic re-dial
and hands free talking, the phone allows sixteen numbers to be dialed by
speaking a single word command such as "school" or "office".
Audec Command Dialer.
1.4 Speech Synthesizers
Computer controlled voice synthesizers are becoming more prevalent in our
Stored voice response systems are regularly used by the phone
company for information about misdialed or disconnected numbers, and in
automobiles for reminders about fastening seatbelts or getting an oil change.
These systems contain a specialized and very limited vocabulary consisting of
short segments of prerecorded speech. Different utterances can be produced by
playing the words in a different order. Sentences often sound unnatural because
the individual words are recorded with little inflection so they can be pieced
together in any order. These systems are relatively inexpensive but with a high
bit rate can produce good quality speech.
Speech can be stored in analog or digital form on a variety of magnetic or
optical media for random access. The large data rate for PCM (see section 2.1.1)
can be reduced through a variety of data compression techniques which
generally take advantage of the relatively slowly varying nature of speech
[Rabiner 78, Flanagan 79].
As the data rate is reduced, the quality and
intelligibility of the synthesized speech tend to decrease.
Synthesis-by-rule is
necessary for applications where speech must be generated from free form text,
as in the reading of electronic mail messages.
Waveform coders use alternative descriptions of the speech waveform, such
as the difference between samples (delta modulation), pause removal, or the runlength encoding of invariant portions of the speech signal.
Parametric coding provides greater compression through a reversible
description of the signal, often based on the vocal tract.
Parameters are
extracted and later used as input to the inverse operation, to reproduce the
spectrum of the original, rather than matching it sample by sample.
Predictive Coding (LPC) produces coefficients which describe the sound as a
linear function of previous samples.
Text-to-speech synthesizers are advantageous because they are not
restricted to a small vocabulary and do not require vast storage or high
transmission bandwidth. There are two popular approaches to a text-to-speech
synthesizer model; one is to generate LPC coefficients, the other is to use the
resonant formants of the vocal tract.
To a first approximation, these two
techniques produce similar results, at a data rate about one-tenth that of PCM
encoded speech [Flanagan 81].
ASCII text is first converted into a sequence of symbols
representing the distinctive phonemes for the utterance. This process can be
performed by a letter-to-sound conversion algorithm or by looking it up in a
dictionary [Allen
76, Allen
combination of these techniques.
Advanced approaches attempt to model
clause and sentence level prosody, including pauses, pitch contours, and stress.
1.4.1 Federal Screw Works
The Vocal Interface Division, of Federal Screw Works produced several early
speech synthesis products, notably the Votrax and Type'n'Talk. The Votrax did
not contain any text-to-speech rules, and is representative of a synthesizer where
the text to phoneme conversion is placed in the hands of the user. Sixty-three
phonemes with four choices of inflection are available to the user, for example
the word "America" would be transmitted to the Votrax as:
1.4.2 Digital Equipment Corporation
DEC has recently announced DECtalk, a new text-to-speech synthesis
product that features multiple vocal tract models which allow different voices to
be synthesized (e.g. men, women, and children). A user definable dictionary
(150 words) and a large (6000 word) built-in exception dictionary in conjunction
with a set of letter-to-sound rules permits DECtalk to produce highly intelligible
speech [Bruckert 84].
MCI Communications, an alternative long-distance telephone carrier, has
recently announced [Zientara 84] that they will be using the DECtalk system in
conjunction with MCI Mail, their electronic mail service. Subscribers call a toll
free number and enter an identification code to have their text messages read to
1.4.3 Speech Plus
Several text-to-speech synthesizers are available from
the CallText 5000,
a board
level product
Speech Plus
fits in the
communications bus of an IBM Personal Computer. A dictionary is augmented
by a set of contextual rules which disambiguate abbreviations such as Memorial
Dr. versus Dr. Backer. The unit for the IBM PC has a telephone interface, with a
DTMF generator and decoder, which permits the synthesizer to be directly
connected to a telephone line.
1.5 Voice Storage and Forwarding
The 1A VSS brings together a unified communication
system incorporating the required transmission paths
and storage media to permit voice communication
between individuals who do not coexist in either space
or time. [Bergland 82b]
Electronic messaging systems, such as voice store and forward (VSF) have
many advantages over more traditional forms of communication. They provide
the ability to get information to and from a person without having to locate him,
worry about time zone differences, or be inconvenienced by interruptions.
Messaging systems can also provide a detailed record of all correspondence,
allow routing of messages to many parties, and prevent the obligatory discussion
of meteorological conditions.
Studies show that "white collar" professionals spend about 25% of their time
in non-interactive communication (i.e. reading and writing), and over 40% of their
time in interactive communications such as meetings, face-to-face conversations,
and telephone conversations [Klemmer 71]. Much of this information exchange
is basically asynchronous; the executive does not require (or sometimes even
desire) interaction, he merely seeks to obtain or distribute information.
interactive communications provide a permanent record and have traditional and
usually slow distribution paths (e.g.
Mail, libraries).
communications not only have the advantage of speed, but allow voice intonation
to carry additional 'meaning.
Only 75% of telephone calls are successfully
connected to the desired party due to a busy line, no answer, etc. This results in
an average of three calls being placed before the game of telephone tag is
1.5.1 Bell Custom Calling Services
Bell Laboratories began research in the 1940s on a centralized method of
the specific component
technologies, architectures, and service definitions continued into the early
1970s when the required technologies had matured sufficiently to enable a cost
effective realization of the Voice Storage System (VSS) [Cornell 82, Gates 82].
The development of a VSS was begun in 1975 with the specific design of the 1A
VSS reaching completion in 1976.
The first 1A VSS was shipped to the Bell
Telephone Company of Pennsylvania in late 1978, with the expectation that the
Custom Calling Services II (CCS 11)features would be placed in service in 1980.
Custom calling services (Call Waiting, Call Forwarding, etc.)
available with the first electronic switching system (no. 1 ESS) installed in 1965.
The VSS provided several new messaging features to the telephone customer
[Worral 82]. Call Answering offers the general capability to answer a call, deliver
a customer recorded greeting, and then record a message from the caller.
Advance Calling allows a customer to record a message and have it sent to a
designated number at any designated time.
Custom Announcement Service
permits a recorded announcement to be delivered to anyone who calls the
customer's telephone number. All of these services can be controlled remotely
by the customer via Touch-Tones or a specially designated telephone number.
Call Answering customers can screen incoming calls as they are being
recorded by dialing a monitor access code. If desired, the customer can flash the
switchhook to be connected to the calling party.
Recordings are terminated
when they attain a maximum message length or after three seconds of silence.
The voice-presence detector permits the recording of continuous signals at high
levels, thus allowing for the storage of encoded data that was generated by
frequency shift keying. Once recording has stopped, the entire message is then
duplicated for enhanced reliability.
Call Answering
Message retrieval
Advance Calling
Message recording
Status check
Custom Announcement
Remote Access
Privacy Code Change
Seven-digit telephone number
t Customers with DTMF signalling telephones may use * instead of the digits 11 (i.e., *51 instead of 1151).
[Worrol 82]
Digit scheme
A Call Answering customer is notified of pending messages by an
interrupted dial tone when the phone is taken off-hook and a short ringing signal
when the phone is hung up. To hear messages the customer dials a retrieval
code, the CA service responds with the prompting statement; "You have had M
calls since you last played back your messages and you have N messages
waiting. " After announcing the day and time of arrival the messages are played to
the customer in the order that they were received. The customer has the ability to
save, repeat, skip, or pause during the playback of a message.
Initial experiments indicated that the human factors aspects of the design
were generally good, but the reliability of service in terms of lost calls, integrity of
the long-term message database and overall throughput of the system was below
expectations. Software was modified and re-tested; three additional VSS systems
were installed in New York, Dallas, and Chicago. In 1980 full-time "friendly user"
service was available to selected telephone company employees at the test sites.
A tariff for the Philadelphia offering was filed with the Pennsylvania Public
Utilities Commission [Nussbaum 82], but was not approved because of a pending
antitrust suit filed by the Associated Telephone Answering Exchanges, Inc. The
suit was rejected, but the FCC ordered that enhanced services encompass the
area of voice storage, which could therefore not be offered as part of the
regulated telephone network. The Bell system filed a petition for waiver of CCS II
but this was rejected in late 1981, the offering was withdrawn and the VSS project
1.5.2 VMX Voice Message Exchange
ECS Telecommunications Inc.
(later changed to VMX Inc.), founded by
Gordon Matthews in 1978 delivered the first commercial voice store and forward
system in 1980. The VMX system uses a modified version of delta modulation and
a parallel processing scheme; a fully configured system uses over 100
microprocessors to handle 3000 voice mailboxes. VMX holds a patent on 51
individual design features of its VSF system, and has settled a court case against
Commterm Inc. by granting a royalty-bearing license on its patent (VMX currently
has two outstanding suits for alleged infringements on the patent).
1.5.3 IBM Audio Distribution System
The Speech Filing System (SFS) was developed at the IBM Research Center
1973-1975 [Gould
82, Gould
In the subsequent six years
approximately 750 IBM executives used the SFS in their daily work; the user
interface was significantly changed and improved during this period. The IBM
Audio Distribution System (ADS), a direct outgrowth of SFS, was released as a
product in late 1981.
The SFS emphasizes spoken messages, but it has been
used to compose and distribute handwritten and typed messages as well.
The ADS has a very extensive Touch-Tone based command set which
permits audio documents to be created, edited, and forwarded [IBM 82]. It can
be customized by the user to create distribution lists, allow others to hear limited
parts of one's messages, or change the amount of prompting from the system.
Distribution lists and individual messages are specified by keypressing the
alphabetic representation of the name. Message playback speed is increased by
automatically deleting pauses between words. An audio-response help facility is
available which is conditioned by the context of the user's current location in the
hierarchical command tree.
IBM Audio Distribution Systern
4 reen inpeid
S ssep gray7~~
plbk mac
AD oprompts;
07 tasm,.itrely
66 a
9 ri 5 on,tevin
9 Plavbackm.g
03 lrinesel
"i B
6 qwily~delst
Ji o
ADS kypad
verla showng tpvl
ADS ca automticall
plac outgong cals.Wnfomtheponosnnwee
ADS prompts;
"Hi, IBM Audio Ditibto
ystoe calmingJhmt.Pes
keypress your password." A person can send messages to himself which not only
serve as personal reminders, but as wakeup calls as well.
1.5.4 PABX Based Voice Storage Systems
A alternative to a stand alone voice mail system is to use a service offered by
an existing telecommunication firm, providing the advantages of voice mail
without any hardware purchases. Unfortunately since the voice storage system is
not tied to a local PABX the caller will most likely have to make two calls, one to
the desired party and one to the service bureau. An advantage of having a voice
mail system that is closely tied to a PABX is that the called party can be notified,
via a lamp or other signal, when a message is waiting or can even identify the
calling party.
1.6 Integrated Telecommunication Workstations
In the future it will no doubt be possible to send mixed
voice and data over a digital network; however to
experiment today we must use the existing analog
network. [Hagelbarger 83]
Telecommunication workstations
which are
integrated with
computers and text mail systems have been appearing in the marketplace with
increasing frequency. Ranging in size from small portable terminals to desktop
workstations closely tied to a digital PABX, these teleterminals are slowly
replacing conventional phones and becoming personalized telecommunications
1.6.1 Bell Experimental Teleterminals
Bell Laboratories has developed a series of experimental teleterminals that
merge the functions of a conventional telephone with that of a computer terminal
[Bayer 83, Hagelbarger 83].
The teleterminal consists of 1) a traditional
telephone facility, 2) a microprocessor for internal intelligence, 3) a data
communications facility, 4) a general purpose display, and 5) dynamic labeling of
-31 -
buttons (soft keys). The first terminal contained a two-finger keyboard and a
small (16 rows by 32 column) video display with a row of six soft keys on either
A unique feature of this terminal is that the functions of the keys are
definable by the user; there is a tree structured profile file that can easily be
changed and updated to suit the user's preferences.
The first Bell teleterminal.
The operation of the teleterminal is perhaps best described by an example
(as in [Bayer 83]). Suppose we wish to call Ellen, the department secretary.
Customization of the tree-file places Ellen's name on the top level screen, as she
is frequently called. Touching the ELLEN button Causes her telephone number to
be dialed, her mail address to be temporarily stored, and the Personal Assistant
screen to be displayed.
This menu allows access to personal appointment
calendars, an electronic mail facility or UNIX on a local host, specialized
directories, etc. If Ellen doesn't answer her phone, a message of the form; "I
tried to call you. Please call me back at x51 56" can be sent with a single button.
When Ellen returns and reads her mail she can respond by touching a RETURN
CALL button which will aUtomatically dial the extension.
triageImarger wsj
A color GETSET.
Several styles of these terminals, known as GETSETS (General-Purpose
Electronic Telephone Sets), which transmit voice and data over separate lines
have been developed [Bergland 82a]. More recent prototypes included models
with higher resolution and color raster displays. The most recent prototype has a
24 line by 80 column display, almost full-sized keyboard, a speakerphone,
telephone interface that imitates a six-button keyset, and a microprocessor
running a UNIX-like operating system. There are eight soft keys at each side of
the display and nine along the bottom.
This teleterminal is part of an
Information and Communications) which is currently used by many Bell Labs
executives [Klapman 82].
The EPIC GETSET teleterminal.
1.6.2 Zaisan Voice/Data Workstation
Zaisan's ES.1 teleterminal combines local computing (32K ROM + 32K
CMOS RAM with battery backup) with standard telephone features and a built in
modem. There are eight soft keys that permit dialing and menu selection from the
monochrome display, 13 user programmable telephony keys, and a detachable
keyboard. Software features include a directory that can be annotated during a
call, calendar/alarm functions, and an electronic mail facility.
1.6.3 Xerox Etherphone
Work at the Xerox has taken a somewhat different approach in integrating
the telephone into the office environment. A specially designed processor called
the Etherphone connects to a telephone instrument and transmits digitized voice,
signalling and supervisory information in discrete packets over an Ethernet local
area network [Swinehart 83]. The Etherphone processor provides the standard
functions of a telephone, but can provide many other services when combined
with the power of a nearby workstation, a voice file server, or other shared
resources such as databases.
- 34-
1.6.4 Telrad Touchscreen Terminal
The Telrad Info 4000, an "Executive Voice/Data Touchscreen Terminal",
allows touchscreen access to telephone directories and other
information. Entries or updates to a personal directory can be made through a
typewriter style keyboard or by directly touching the screen. The terminal permits
simultaneous voice and digital data transmission over the same line.
Telrad 4000 with touch sensitive screen.
1.6.5 French Telecommunications Videophone
The French PTT is installing an optical large fiber network in Bairritz France.
A high bandwidth videophone is used to combine voice and image, as the Bell
Picturephone attempted to do in the 1960's [Cagle 71]. The videophone can also
be used as an enhanced videotex terminal which can access photographic still
images, movies, and sound sequences stored on videodiscs at a central location.
Videophone used for visual telephony and videotex.
Chapter Two
The Phone Slave
"I've frequently seen parents who were slaves to the
phone and all the calls were for their teen-age sons or
Karen De Witt, The Washington Post, February 28 1977
This section presents an introduction to the hardware and software
environment that were used in developing this project. Two predecessor systems
are described upon which the telecommunications management system was
built; a voiced electronic mail facility and an interactive answering machine.
Collectively all of this telecommunications work has fallen under a project called
the Phone Slave3 . This work has branched in two main directions, a subscriber
service that allows anyone in the lab to read their electronic mail over the phone,
and a personalized integrated telecommunications system. For the sake of clarity
these will be referred to as the Phone Slave and the PITS respectively.
2.1 Computing Environment
All of the devices described herein are peripherals to a Perkin-Elmer 3230, a
32-bit general purpose minicomputer, running MagicSix, a Multics-like operating
system developed at the Architecture Machine Group [Steinberg 74, Parks
79, Kazar 78, Kazar 80, Boyle 81]. PL/1 is the language used for most systems
and applications programs. MagicSix has a powerful screen oriented text editor
(Emacs), a large body of support software for frame buffer graphics, including
grayscale fonts, and device interfaces for speech recognition, synthesis, and
digital sound equipment.
3 At
the objection of the author.
This is a flexible development system which permits projects such as this to
be implemented in relatively short period of time. There is nothing inherent in the
software or hardware design which requires a large processor or expensive
peripherals. This work is seen as a prototype for a for a system that is integrated
around a personal computer with a speech processing board, such as the Texas
Instruments Professional Computer.
Several generations of hardware, particularly the telephone interface, have
been built during the course of the project. The first phase used two heavily
modified speakerphones as a 2-to-4 wire converter and a speech recognizer as a
crude DTMF decoder! The following descriptions will discuss the hardware
configuration in its current state.
Hardware configuration.
2.1.1 Sound System
The sound system is a set of software routines that manipulate data on a
magnetic disk and a specialized hardware device known as the soundbox
[Vershel 80].
It is an eight channel system that permits up to four different
sounds to be played simultaneously.
The sound box, designed and built in-house, contains a group of analog-todigital (A/D) and digital-to-analog (D/A) converters. Acoustic input is digitized at
a rate of 8000 samples per second using 8-bit linear pulse-code modulation
(PCM), providing a signal-to-noise ratio of about 50 dB.
This sampling rate
permits sounds below approximately 4000 Hz to be accurately recorded and
reconstructed. Higher quality voice reproduction can be achieved at the same
data rate with logarithmic rather than linear digital encoding. A United States
standard for speech coding, known as mu-law encoding, has been developed
which provides the equivalent dynamic range of 12-bit linear PCM using only
eight bits [Henning 72].
At the rate of 64 kbits per second, storage of the digitized speech becomes
expensive in many computing environments (this project has 85 megabytes, or
135 minutes of disk dedicated to sound storage). Many speech compression
techniques exist (see section 1.4) for reducing this data rate to 1200-9600 bps
intelligibility and
ability to
identification. This data rate reduction puts speech storage, reconstruction, and
recognition tasks within the realm of commercially available personal computers.
2.1.2 Voice Synthesizer
A Prose 2000 text-to-speech synthesizer [Telesensory 82] is used to read
text messages and provide feedback to the caller. This unlimited-text synthesizer
was chosen because of its natural prosodics which are very important for the
understanding of free form text [McPeters 84]. (A description of speech
synthesizers occurs in section 1.4)
2.1.3 Speech Recognizer
The DP-100 Connected Speech Recognition System from NEC (Nippon
Electric Company) is capable of recognizing up to five words or "utterances" per
spoken sentence. In this application the DP-100 is primarily used as an isolated
word recognizer, yielding significantly higher recognition rates. (A general
description of speech recognizers occurs in section 1.2)
The recognition response time at the end of each sentence is about 300
milliseconds. Output is communicated to the host computer via a high speed
serial interface and is also displayed on an alphanumeric plasma display. The
device has a maximum vocabulary of 120 utterances, which are stored in the
active memory of the recognizer as a set of reference patterns. Each word slot is
trained only once and the reference patterns cannot be altered under software
control, although individual word slots can be retrained.
The DP-100 speech analyzer performs spectrum analysis, and transforms
the input speech signal into 16-dimensional spectrum vectors every 18ms using a
digital filtering technique. The filter bank covers a frequency range up to 5900Hz
[Tsuruta 79], while the standard voice frequency channel used in telephony is
nominally limited to 3000Hz. The DP-100 is therefore unable to use its full range
of spectrum analysis capabilities in differentiating utterances. This is particularly
a problem for recognition of female voices where there is a larger energy content
in the higher frequencies.
In order to train the DP-100 in such a way as to
minimize the effects of this limited bandwidth all training was performed over the
telephone [Dautrich 83].
Statistics of the errors and rejections made by the DP-100 were not kept,
however, we experienced a high recognition rate over local telephone lines
(within MIT's CENTREX system). Recognition over long distance lines was next
to impossible due to the varying types and amounts of background noise.
Recognition rates could be increased if a speech recognizer was tailored to work
within the limited bandwidth of the telecommunications channel and dynamically
adapt to the background noise level. Note that the DP-100 is by no means the
ideal recognizer for this application.
2.1.4 Telephone Interface
The phonebox is a specialized piece of hardware consisting of a subscriber
line access circuit, 2-to-4 wire converter (hybrid circuit), DTMF decoder, and
audio switch bank that communicates with the host computer over a single serial
line. A Hayes Smartmodem is used as an auto-dialer and to detect an incoming
ring signal on the phone line [Hayes 82]. This modem was chosen, rather than
building the equivalent tone generation circuitry, because of its relatively robust
software interface and a desire to explore mixed data and voice communications
over the existing telephone network.
The phonebox: 2-4 wire converter, DTMF decoder, and audio switches.
A 2-to-4 wire converter is needed to separate the transmit and receive
signals from the telephone line, which is a two-wire circuit that provides full
duplex operation. The 2-to-4 wire converter only provides 20dB of isolation, an
insufficient amount to prevent outgoing audio (e.g synthesizer or digitized voice)
from being fed back to the speech recognizer. In our current configuration it is
not possible to perform recognition while the machine is speaking, so the DP-100
is temporarily disconnected from the audio circuit. A better hybrid circuit or a
voice operated switch monitoring the line would permit the caller to interrupt the
machine by voice.
2.1.5 Graphical Interface
Color graphics workstation with touch screen.
Graphics and text are generated in a Ramtek 9300 frame buffer with
640x480x9 bit resolution. The touch sensitive display (TSD) is a commercially
available, visually transparent, digitizer that is overlayed on the face of a video
monitor [Elographics 80]. The grayscale or "soft" fonts that are used for text
display were developed at the Architecture Machine Group for dense display of
near-print-quality text on a conventional NTSC color television [Schmandt 83].
Characters are displayed as two-bit images, spatially low pass filtered, producing
what is perceived as a high quality resolution image on a low resolution display.
A standard resolution television monitor is advantageous in that it has the ability
to mix computer generated graphics with other video images such as a video disc
[Arons 84, Gano 83].
asses As
see .M00
1.*- ones
a *.own*
AN .0
Editor used in designing the grayscale fonts.
Color is used to convey information as well as to be pleasing to the eye. Text
and graphics are displayed in low saturation colors on a neutral background.
When an element is touched it is highlighted to visually confirm that the action
has been registered, when the command is completed the colors fade into
2.2 Voice Reading of Electronic Mail
Electronic mail (Email), conventionally read on a CRT terminal connected to
a centralized computer, is a common and growing mode of communication in
many commercial and academic environments. A user can quickly summarize
his correspondence, disregarding cryptically encoded headers, while mentally
noting which messages are long or require immediate attention.
He has the
ability to selectively read, delete, or respond to individual letters. While at home
or traveling, access to a terminal and a modem may be limited, and a regular user
of Email may be out of touch. Inexpensive portable computers and terminals with
integral modems are becoming more prevalent, but remote access to electronic
mail without special hardware is desirable.
A voiced electronic mail facility developed at the Architecture Machine
Group provides simple efficient access to an electronic mailbox using a TouchTone phone as a remote terminal [Baker 83].
A text-to-speech synthesizer is
used for reading the text of the letters and providing instructions to the user. This
facility is currently operating as a general utility at the Architecture Machine with
approximately 20 people actively using it. When a call is placed to read one's
mail, the caller must identify himself with Touch-Tones. We currently use the
caller's seven digit home phone number as a unique identifier, with an optional
four digit password.
There are many approaches and possible mappings of the functions of a
DTMF driven system onto the twelve keys of a Touch-Tone telephone. A common
method is to relate the letters on the key with a mnemonic that corresponds to
some system function.
For example in IBM's Audio Distribution System (see
section 1.5.3) uses the PRS key to RECORD a message. One drawback to this
technique is that the assignments of letters to keys is predefined, and it may be
difficult to find suitable mnemonics that can be used on all the keys. Another
approach, often used in conjunction with mnemonics, is the use of a hierarchical
This technique permits a virtually unlimited number of
menu structure.
commands using only 12 keys, however the command tree is often complex and
may require a manual describing all possible options.
Get Intothe system
To select UserOptions
Enterlist number(01through09)
the curren
a list
the current
for thies
shown above
Note: The List Featur e described In detail
under the Key Descriptiont.
A commercial hierarchical command tree.
The design philosophy for the Phone Slave system at the Architecture
Machine Group was a little different. The goal was to distill the desired Email
functions down to a minimum repertoire so that a tree structured command set
would not be needed. A geographical rather than mnemonic approach was used
for the assignment of commands to keys, for example, NEXT MESSAGE is adjacent
to the PREVIOUS MESSAGE key, both of which neighbor the NEXT SENDER and
Keypad command layout for the Phone Slave.
Another important design consideration is that the system is always
interruptible and responsive.
The choice of appropriate default actions is
significant in this type of interactive system. The default condition, in this case, is
to lead a naive user through all possible options and play all the messages. An
experienced user can anticipate the action, interrupt the synthesizer, and redirect the flow of control.
This feature makes the system truly interactive,
allowing the user to do what he wants when he wants it.
As speech is relatively slow compared to reading, it is important to present
spoken information in a coherent format, providing the user with as much
information as possible, without overloading him with useless details.
viewing text messages on a terminal it is possible to scan them and move
amongst them in a random access fashion. It is easier to understand messages
and their inter-relationships when the information is presented visually by the
screenful than when read orally in a sequential fashion due to short-term memory
limitations [Miller 56, Luce 83].
This situation is analogous to reading a newspaper versus watching a
television news broadcast; in both cases the information is presented to the
viewer, but it is possible to browse with the newspaper. The reader can jump
between stories that are of interest, rather than hearing about stories that the
newscaster chooses. Messages, as in the case of news, should be presented in
order of importance rather than chronologically. In this voiced mail system they
are grouped by the the originator of the message and sorted in order of the
number of messages from each sender.
This feature exploits the fact that
multiple messages from the same person are usually indicative of an ongoing
coherent set of correspondence.
The mail is preprocessed, stripping off the body of text and removing the
bulk of the header information.
The header usually contains the time the
message was sent and received, the sender's network mail address, etc. This
burdensome to to hear at speech rates.
By default it is not presented, but
available on a per message basis through the use of the the MORE INFO key.
An early Phone Slave keypad template.
Mail is presented in such a fashion as to provide the user with as much
information as possible without forcing him to hear the entire contents of a
A short introduction such as "this is a rather long message, it's
about..." is spoken to give an indication of the content and length of the text. A
short message is simply read without any introduction. The synthesizer's pitch is
altered when it is speaking about a message as compared to when it is actually
reading the text. This differentiation was explored as a means to increase the
ability to comprehend the transitions between messages.
While the intelligibility of the Prose 2000 is significantly greater than its
predecessors, it can at times be very difficult even for a trained user to
understand [Nusbaum 83]. Mispronunciations commonly occur with acronyms
and proper names, particularly those of foreign origin. In order for names and
abbreviations that are used frequently in the environment of the Architecture
Machine to be pronounced properly, the text is preprocessed through an external
software dictionary before being sent to the synthesizer.
If a word cannot be
understood, the REPEAT key permits the current sentence to be played at a slower
rate. If the REPEAT key is pushed a second time within the same phrase, the
synthesizer is put into spell mode, thus enunciating each letter.
Here is a sample dialogue with the voiced mail system:
Please enter your I.D., use the star key to
cancel the transaction and restart.
720 0232
Hello Barry, nice to hear from you.
You have five new messages.
Do you want to read your mail? Press 7 if
if no.
(no response)
4 from Chris Schmandt.
Message 1, it's about "C.E.S. Paper."
Do you care to hear this one?
(after a short pause the default is to play the message)
We should start working on a longer and more
complete version of the ICCE paper for the IEEE
Transactions on Consumer Electronics.
Can we
talk about it later today?
What kind of reply would you like? 7 for
(interrupts to send affirmative reply)
Mail was sent.
Message 2, this is a very long message, it
begins "New synthesizer specifications."
Do you care...
Ok, next sender.
1 from Louie Weitzman.
I'm glad to hear you're getting a new bike.
Have you seen a Bianci?
I'll repeat it for you.
Hhaavvee yyoouu sseeeenn aa BBiiaannccii?
spell it for you.
OK, I'll
H-A-V-E Y-0-U S-E-E-N A B-I-A-N-C-I?
You want more info: Louie Weitzman, logged in as
[email protected], yesterday at 5:.25 PM.
2.3 The Interactive Answering Machine
A parallel research effort was an interactive answering machine, an
intelligent message taking system which asks questions and records responses.
The machine uses a limited amount of speech recognition as well as some simple
heuristic measures to steer the conversation in the right direction.
conversation is robust enough to handle naive callers as well as those familiar
with the system. The stereotypical consumer answering machine's "I can't get to
the phone right now, please leave your message at the tone... BEEP", does not
provide the caller nor the machine's owner with much information. Rather than
being rigidly tied to a single informational announcement and fixed length
recording, the conversation can take many paths depending upon the caller's
identity (see diagram on page 67).
At this point in time it is not feasible for state-of-the-art speech recognizers
and computers to monitor and analyze a free form human reply to a question. It
may be possible to use a speech recognizer to do keyword spotting, but the
syntactic and semantic analysis of these fragmented sentences is beyond the
scope of current software and hardware. Rather than attempting to tackle these
difficult problems in this manner, a much simpler scheme was used.
The computer seizes control of the conversation and leads the caller
through it by asking questions and listening to the responses. In order to format
the responses for later retrieval, the questions are stated in such a way that they
elicit a very specific response. Five questions are asked (see section 3.1 for
sample dialogues), the responses to which can be categorized as: caller's name,
topic of the call, telephone number, time to call back, and a full message.
When someone calls they are greeted by the machine and queried for their
The machine's voice in this case is a human voice that has been
previously recorded on the sound system.
For our prototype system a female
voice was chosen to contrast it with the owner's voices (currently both male), not
because of cultural stereotypes [Leveen 83].
The greeting is of the form "Hello, Barry's telephone speaking, who's calling
please?". The phrasing of this sentence 1) greets the caller according to the
American custom, 2) informs him of who's telephone he has reached, 3) states in
a nonobtrusive manner that he is talking to a machine, and 4) asks him for his
name. The soundbox is now put into record mode and the DP-100 is connected
to the audio line to monitor the caller's voice.
The response is recorded until the caller has stopped talking, a point which
is determined by an adaptive pause and background noise detector. The data
from the soundbox A/D are analyzed in real-time to determine the background
noise level.
There are several timeouts associated with the recording of a
1) how long to wait for the person to start talking, 2) after he has
started, the length of silence necessary to determine that he has stopped talking,
and 3) the maximum message length. The first timeout is fixed while the second
can dynamically increase if the person is speaking slowly with pauses between
words or phrases.
If the caller exceeds the maximum message length, it is assumed that he is
not answering the question properly. The machine interrupts the conversation in
a louder voice, informs the caller that he is speaking to a machine and asks him
to simply answer the question. After a message has been recorded it is power
normalized so that all messages, regardless of the level of the speaker's voice or
the telephone connection, can be played back at the same volume. Although not
currently implemented, the machine could ask the caller to speak up if it sensed
he was speaking to softly.
The DP-100 is designed to be neither a speaker identification nor a speaker
verification system [Rosenberg 76]. Within the context of this project, however,
-51 -
we did use the speech recognizer as a means of identifying callers. The DP-100
was trained to recognize the owner and his most frequent callers identifying
themselves over phone.
People generally identify themselves in the same
manner when speaking over the phone (e.g. "Hi, this is Barry" or "It's Chris"),
and this identification signature is used to train the DP-100. After a conversation
with an unknown caller the speech recognizer is trained on their recorded
identification signature. This permits the answering machine's owner to leave
personal recordings for all callers, even those who are not currently entered into
the owner's telephone directory.
If the caller's identification signature is recognized, the conversation takes a
different branch and carries on a more personalized dialogue. A frequent caller
is familiar with the machine and vice versa, so it is not necessary to ask the
default questions. Information, such as the caller's telephone numbers, is known
to the machine so these items are not requested unless they need to be updated.
If a known caller is inadvertently not identified by voice, he may enter his ID with
Touch-Tones once he realizes that he was not greeted by name.
A known caller receives a personal recording from the owner and an
acknowledgment as to the status of any messages previous left by the caller (see
section 3.1).
The message that a caller receives can be of three of different
types: 1) a personal message from the owner to the caller, 2) a message for a
class or distribution list of people or 3) a general message of the day.
It is
possible to leave a message for everyone who belongs to the class Architecture
Machine Group that says "I will be home tonight working on my thesis," while a
message could simultaneously exist for the class DKE fraternity brothers that
says "Let's get together tonight for a few beers."
The message of the day can be created at anytime or it may be chosen from
As with the previously described Email system, his home number.
a selection of previously recorded standard messages, such as "I'm out to lunch
and will be back at 1:00."
selected by the owner.
At present, these recordings must be explicitly
The selection of outgoing recordings could be
automatically invoked by the machine based upon the owner's weekly schedule.
For example, the recording that states "I am in Lippman's Digital Video class
today, try again after 3:30" could be activated on Tuesday and Thursday during
the appropriate hours.
Chapter Three
The Personal Integrated Telecommunications System
This one might be too far fetched. Wouldn't it be nice
to be able to walk into your office and say out loud
"Call Harry" and the phone would automatically dial
Harry without having to touch any buttons. Computers
can easily be taught to recognize simple voice
commands. Why not phones?
Holiday Wish List, Teleconnect Magazine, December
Though involved in the design and implementation of the previously
described subsystems, my work focused on the integration of these tools with
other telephony functions, such as auto-dialing and directory management, to
create a unified user interface5 to a personalized telecommunications system.
Interaction occurs in three forms; locally via a color raster display terminal with a
touch sensitive screen, or remotely over the phone using either voice commands
or Touch-Tones [Schmandt 84a, Schmandt 84b]. This multi-mode access
strategy provides convenient, efficient, and flexible message retrieval through a
consistent user interface.
Messages gathered from two sources, electronic mail via a local area
computer network and voice messages from the interactive answering machine,
can be readily accessed by the owner. These messages are aggregated so that
the owner can view them from a single source. He no longer has to deal with a
computer and terminal to view his electronic mail messages and a different
computer and terminal (probably a telephone with a Touch-Tone keypad) to hear
his voice messages.
The system owner's interface.
There are three graphics screens which allow touch access to all the PITS'
functions. A message summary screen shows the status and permits access to
all incoming messages. The card-file screen enables the creation of outgoing
recordings through the use of an on-line directory. The keypad screen allows
dialing by name and the placing of other outgoing calls. Transitions between
screens are made through the small ideograms at the bottom of the screen.
Voice and text communications are represented on the summary screen by
bars indicating the length and current status of each message. Mail messages
can be viewed locally by displaying a text window on the screen.
electronic mail is read using the voiced mail facility previously described.
3.1 Demonstration
The next few pages give a brief introduction to the PITS as it is currently
implemented. The same dialogue is shown in parallel for the three interaction
techniques to highlight their similarities and differences.
The following notation is used to differentiate the speech sources:
-The system owner and callers are in the standard text font.
-System prompts played from the soundbox are in italics.
text-to-speech synthesizer is in typewriter font.
The telecommunications system at
its initial state displaying three
unviewed messages. The first
message is a voice message from a
known caller. The second and third
messages display a subject field
extracted from the electronic mail
message header.
An example dialogue with an unknown caller:
machine: Hello, Barry's telephone speaking, who's calling please?
caller: Charlie Evans
m: What is this in reference to?
c: My visit to your lab.
m: He's not available at the moment, but he left this message:
At what number can he reach you?
When will you be there?
I should be around here the rest of the evening.
Can I take a longer message?
I just wanted to confirm tomorrow's visit to the Architecture Machine.
I'l be sure he gets that. Thanks for calling. Goodbye.
An example dialogue with an known caller:
m: Hello, Barry's telephone speaking, who's calling please?
c: It's Chris.
m: Hello Chris. He got your last message.
If you'd like to leave another message I'll record it now, otherwise, just hang
up and I'll tell him you called again.
Now that I've got the Linear Predictive Coding software for the IBM PC
running we should try doing speech recognition using the LPC coefficients.
If you can't be reached at your usual number, please tell me where to have
him call.
(could have spoken number or used keypad to enter 256-9562)
Thanks, I'll give him your message. Bye
Message screen after arrival of the
two new voice messages. Note that
the two messages from Chris are
grouped together, and the five
message segments from the
unidentified caller (Charlie).
Upon returning to his personal
computer, the owner touches the
top of name column to see who
The owner calls his machine and identifies himself:
machine: Hello, Barry's telephone speaking, who's calling please?
owner: Hi this is Barry.
m: Hi Barry, you have five new messages. Two from Chris.
o: Who left messages?
m: CHRIS, CHARLIE EVANS, Rosanne, Walter.
720-0232 (enters his ID with the keypad)
m: Hi Barry, you have five new messages.
Two from Chris.
As CHARLIE EVANS is played, the red
bar changes color in sync with the
recording to give a a visual
indication of the proportion of the
message that has been played.
Any individual message segment
may be viewed by directly touching
it. In this case Chris's voice
message about LPC is heard.
o: What did he say?
3m: Message one.
When a text window is displayed,
the remainder of the display is
faded. A long text message can be
paged through by touching the
page turn symbols in the upper
Next Message.
Message two, it's about "Japanese Video Tape."
What'd he say?
We will re-shoot Phone Slave videotape, in...
m: Message two, its about "Japanese Video Tape."
Do you care. . . (interrupts)
m: We will re-shoot Phone Slave videotape, in...
The second page of text.
The entirety of a message, in this
case the unidentified caller's, can
be heard by touching the date box
on the left side of the screen. The
message segments which have
been viewed are displayed in a gray
similar to the background, the time
segment is currently being played.
o: Next person.
m: One from CHARLIE EVANS.
o: What's it about?
o: What's the message?
o: What's his number?
m: 494-8683
o: When should I call?
o: When was it?
m: Message received this evening at 7:00.
Hj3 0: MORE INFO-6
m: Message received this evening at 7:00.
Touching the small card-file image
in the lower left hand corner causes
the directory screen to be
displayed. The top everybody card
is used to create and update the
current default message of the day.
The currently selected outgoing
recording is sleeping late.
Touching any card causes that
card to be brought to the front.
The small record symbol permits an
outgoing recording to be recorded
for the Architecture Machine Group
mailing list.
o: Take a message for the Architecture Machine Group.
m: Ready to record.
o: Charlie Evans is up from Florida and will be visiting the lab at 4:00, the
Media Room and Pamela will not be available until 5:00 pm.
m: Stopped recording.
0: REPLY-9
m: Please keypress the name of the person or group for
whom you wish to leave a message.
o: ABC-2 PRS-7 ABC.-2 (enters name using the the keypad)
m:Recording a message for the Architecture Machine
Ready to record.
o: Charlie Evans is up from Florida and will be visiting the lab at 4:00, the
Media Room and Pamela will not be available until 5:00 pm.
m: Stopped recording.
Touching the wx tab brings the
appropriate directory entries to to
front. The bar under the record
symbol indicates there is a personal
recording pending for Rosanne. A
phone call is placed by touching
the handset ideogram in the upper
left corner of the card.
o: Tell me about Rosanne.
m: Rosanne Wagger, her home number is 742-1797,
number is 494-8250
The home or work telephone
number is selected based on the
time day. A call can be
disconnected by touching the
phone, causing it to drop to is
normal position.
Telephone numbers may be
entered directly using the keypad,
the backspace key can be used to
correct mistakes.
The locations for area codes and
local exchanges are displayed after
three digits have been entered.
The local time is displayed for calls
placed to other time zones.
3.2 Design Considerations
The owner's interface makes no distinction between text messages and
voice messages, there is only a simple generic message.
Interaction in this
system is actively directed by the owners who queries and converses with the
Access is multi-modal, with the same basic information accessible through
any input technique. Upon receipt of a command immediate feedback is given,
the style and content of which depend not only on the state of the messages, but
upon the input technique as well.
For example, the "Next sender."
entered by voice will cause the machine to say "one from Chris", and wait for
further directives before playing any piece of Chris' message. If the NEXT SENDER
command is registered through Touch-Tones, the entirety of Chris' message will
be played, as this is the limit of command detail available through the keypad.
As with the voiced Email subsystem, the messages are aggregated by the
originator of the messages, thus making it easier to follow an ongoing dialogue
when remotely accessing the messages. The relative weighting of voice and text
messages is alterable. The owner may feel, for example, that a voice message
has more urgency than a mail message and that it should have a higher priority.
The owner can also tell the system "I'm expecting a message from Rand" which
will cause any messages from Rand to be flagged and presented first.
3.3 Remote Access
The primary mode of remote message access is by voice, although a limited
number of commands are available through Touch-Tones7 . The keypad provides
6In the voiced mail system all messages would be heard by default without intervention by the
user (section 2.2).
The keypad layout is consistent with the voiced mail facility.
a backup channel for voice commands over noisy phone connections and allows
the synthesizer or soundbox to be interrupted. Voice access permits detailed bits
of information to be extracted due to a large vocabulary.
Upon calling his
personal telecommunications manager, the owner identifies himself, is greeted
by the machine, and given a brief summary of its status. From this point on the
system is actively driven by the owner; commands are spoken, and aural
feedback is immediate.
Who's calling please?
Status of last message.
Pesonal mesg
1- pUrMM smifio
Phone numr'?2.go
Wha time?
New message
message or hangup
phone number?
number or hangup
(train recognizer)
Tree of possible conversations.
There are three main command classes. Global commands allow queries as
to the overall state of the system. For example, "Who left messages?" causes the
names of the message originators to be listed, the overall state of the system is
left unchanged. Relative commands such as "When was it?" or "Next person."
are used to move among the messages or within the current message. The last
class of commands, pertain to a specific person or group.
"Tell me about
Walter." would cause information about Walter, such as his phone number and
whether he called in to receive his personal recording, to be spoken.
Personalized recordings can be created and left for any individual or
distribution list. No voice storage is assumed to exist elsewhere, all messages are
stored locally. If the party has an electronic mail address, mail of the following
form is sent informing them of their pending voice recordings:
Date: Wednesday 4 January 1984 15:34:21 EDT
From: Barry Arons <[email protected] mit-pamela>
Sender: The PITS <[email protected]>
Subject: Reply to your message about Deep Dish Pizza.
To: Allyson Haut <[email protected] ucolumbia.bitnet>
I left a voice message for you on my telephone (617) 258-6681.
You can hear it by identifying yourseJf or keypressing the
identification number: 01057.
After receiving this electronic mail message, Allyson could call in to hear this
recording in two different ways. She could enter the unique identification number
(01057) to play that specific recording, or she could call and identify herself by
voice. In this case she would be engaged in a limited conversation as described
3.4 Graphical Access
The bit-mapped display graphically represents all the incoming and outgoing
communications, the owner can peruse messages with a simple touch.
screen organization is a two-dimensional analog of what is presented verbally.
Visual cues, through color and graphical ideograms, are given regarding the
length and status of messages, telephone numbers, etc.
The time and date of arrival of each message is displayed, not in the
conventional month/day/year-hours:minutes:seconds format, but rather in times
relative to the present.
If the message arrived recently, it says "Today",
"Yesterday" or "Friday". Times are rounded to the nearest five minutes and
presented in AM/PM format. If a message becomes older, the precise time of
arrival becomes less important and only the date is displayed.
Touch screen access to information.
The name of the sender is displayed, if known, but only once per screen to
keep the display uncluttered.
The interactive answering machine breaks a
message up into five distinct pieces; text messages generally consist of a topic
and body of text. These consistent classifications permit the message segments
to be displayed and organized by content.
Colored bars are used to represent each of the individual message
segments. The length of the bar is proportional to the length of the message, its
color is indicative of its status. An unviewed message is red, to draw attention.
The bar changes to blue in sound sync with a message as it is played. After it is
viewed it changes to gray, fading into the background.
Touching any region immediately highlights it and activates it. An individual
segment of a message may be viewed in a random access fashion, or an entire
row or column can be played. A command can be interrupted at any time by
touching a new region.
Mlla 2=
DUN 1*1
13; &! 1113
Designing the colored ideograms with the font editor.
Touching the HANDSET ideogram at the bottom of the screen while viewing a
message invokes a new screen which permits calls to be made. It is possible to
place or return a telephone call in several ways. The home and work numbers of
the individual are displayed, with the preferred number is highlighted based upon
the time of day. Touching a number causes the telephone HANDSET ideogram to
raise and the number to be dialed. The owner's voice is picked up by a
microphone, the called party is heard over a speaker. The call will be
disconnected if a busy tone is detected or by touching any other active region on
the screen.
If someone is to be reached at a number that is not in the directory, it can be
input via the keypad. The number is displayed character by character as it is
entered: a backspace key is provided so the entire sequence need not be reentered if an error is made. After three digits have been entered the location of
the called number is displayed based upon the area code or local exchange. If
the location is in a different time zone, the correct time for that locale is
Example of local exchange lookup.
A card-style directory permits dialing-by-name and the creation of several
classes of outgoing recordings (see section 2.3). The file contains 25 labeled
cards; A through Z, and lists which contains the various mailing lists. Individual
cards with entries are displayed in light blue, empty cards are gray.
A group mailing list with an outgoing recording.
Recordings can be created for individuals or groups by touching the dual
reel RECORD ideogram on the appropriate card.
-71 -
The owner is prompted by
changing the RECORD ideogram to red and by a verbal "Ready to record" cue.
When the owner stops talking, the recording is stopped and the display is
updated. As on the message viewing screen, the colored bar may be touched to
review the outgoing recording.
3.5 Software Design
The PITS software system adopts some of the principles of object-oriented
and data-directed programming, but is implemented within a procedure-oriented
context. The availability and creation of software tools and high level interfaces to
physical devices was crucial in developing a software system as complex as this.
Most device dependent calls are isolated in a few selected low level routines so
that only minor changes would be necessary to use an alternative frame buffer,
speech synthesizer, or sound system which employs the same high level calling
Two design considerations played an important part in formulating the the
overall structure of the software system; the system had to be interruptible at all
times, and multi-modal input had to be handled in a consistent manner. The
machine, regardless of its state, can always be asked to stop what it is doing and
be redirected to begin another task.
Due to the timing dependent nature of the communication protocol with the
speech recognizer, it is not possible to have the DP-100 generate hardware
interrupts, so the device must be polled. The input devices produce data in a
variety of forms: the DP-100 transmits slot numbers in the range 0-119, the TSD
produces x and y coordinates between 0-639 and 0-439, and the DTMF decoder
outputs the common 0-9, *, and #. These diverse inputs are all converted into a
common form so that, when appropriately tempered by context, they all represent
meaningful commands such as "Next message." or "Take a recording for
3.6 Multi-modal Input Interface
With a limited command set it is often necessary to allow a simple global
command (e.g. YES or NO) to have multiple meanings dependent upon the
environment in which it is invoked. This becomes most apparent when using the
limited set of 12 Touch-Tone keys for input. The scheme used throughout the
software system is relatively simple yet powerful. Devices are polled from the
lowest level of software. Whenever a command is entered, the polling routine
halts execution and checks to see if there is a local handler for the particular
input received. If such a handler does not exist, the newly entered command is
passed up to the next highest level of subroutine, where again there may a local
command handler. This happens repeatedly until a local handler is found which
can deal with the input. The top level of software can handle all commands.
Input from the various devices are converted into a common command
language so that all routines can manage the data in a consistent format. The
vernacular used consists of two parts in the form:
where <type> is the syntactic category and <instance> specifies the item to be
operated on 8 . This scheme allows simple syntactical rules to be easily applied at
the lowest level. For example, the command "Tell me about Walter." is broken up
<type = 7> a person specific command, <instance = 2> "Tell me about"
<type = 5> a person, <instance = 22> "Walter Bender"
A syntactic analysis routine checks that the types are consistent for a properly
formed command.
For example, if "Walter" was not recognized, the machine
would ask "Which person?"
The system is data-directed in that a request to the dispatcher, or top-level
command handler, may be an abstract play a message request in which the
This technique was first implemented by Eric Hulteen in Put That There [Schmandt 84c].
message type is not explicitly stated. The invoked routine is a generic operator,
that is, a procedure that operates on a variety of data types, each with a different
natural mode of presentation [Abelson 84]. The manner in which the message is
viewed is a function of data type and the state of the telecommunications system.
Data structures contain the current state of the machine, the current command
and its mode of input, whether a message is being viewed, and which devices are
currently configured to be in use.
An object-oriented graphical interaction system was developed which
permits the types and instances to be properly assigned to the TSD input within
the low level polling routine.
Commands entered through the keypad or
recognizer map directly to types and instances, however, coordinates from the
TSD must be tempered by the current state of the display. The same x-y pair from
the TSD may mean "What's Walter's phone number?" or "Take a recording for
the Architecture Machine Group.", depending upon which screen is currently
During system initialization a database is created which contains the types
and instances for active regions of all possible screen configurations. A storage
reduction scheme is used which allows one screen and up to two overlays to be
active simultaneously.
For example, there are 25 possible positions for the
lettered tabs of the card-file, each of which must be maintained as a separate
item in the graphical interaction database.
There can be up to five personal
directory cards present on top of the card file, so rather than using 25*5 = 125
entries 9 for all possible combinations of cards, only 25 + 5 = 30 entries are used.
Where each entry contains eight fixed point numbers for each of the 25+ active region on the
Active regions of the card file with three overlay cards.
Whenever the display changes, such as when switching to the keypad
screen or removing a card from the top of the card file, a call is made to the
graphical interaction database to update its current state variables.
When a
gesture is registered on the TSD, the graphical database is called with the
coordinates of the touch, and the type and instance for the activated region are
Another object-oriented database manager serves as a personal telephone
directory and maintains all outgoing recordings. Each directory entry contains
the time the person last called, a usage count, a linked list of pending personal
recordings, phone numbers, and addresses.
Requests must be made to the
database manager to create, update, delete, or obtain information from the
database. This provision insures that the database will always remain internally
Chapter Four
Bit by bit, the telephones are becoming digital
dinosaurs. Just as the Touch-Tone surpassed the
rotary dial, new technology will make the Touch-Tone
beeps obsolete... In fact, if your phone isn't also a
personal computer, the chances are your personal
computer will also be a phone.
Michael Schrage, The Washington Post, December 13
The personal integrated telecommunications system is self-disclosing and
intuitive, and can be used without any prior training 10 .
Commands and
interaction techniques are consistent throughout the entire system. The colored
message bars, for example, are used to both represent outgoing recordings in
the card-file as well as pending incoming mail on the message summary screen.
The same techniques are used to create recordings for mailing lists or
Many of the PITS design considerations were meant as an exploration of the
interface, not as a statement of the definitive way to do things. The date and time
format developed, for example, is not desirable in some systems, but has been
found useful when this information must be communicated by voice. The cardfile is organized so that each labeled card tab always appears in the same relative
position (e.g. the "A" card is always on the left).
This style of card-file was
chosen to assist the owner in locating the card that he uses often, and follows the
same physical constraints of an actual Rolodex.
10A demonstration of the system can be seen by viewing the short videotape which
accompanies this thesis. The five minute tape shows the conversationality and intuitiveness of
the PITS, something that is extremely difficult to describe in words and still photographs.
Within the Architecture Machine Group, users of the Phone Slave tended to
listen to their mail in the default order, and features such as MORE INFO were not
used very often. The change in pitch of the synthesizer was not found to be
particularly helpful in distinguishing informational announcements from the
Distinctly different voices (e.g. male vs.
actual text of the Email messages.
female) would perhaps be more effective.
The conversational answering machine was found to be surprisingly
effective at gathering coherent messages. On-the-fly training of unknown callers,
while not always successful, is enhanced by the use of a connected-speech
recognizer. If someone calls and initially identifies themself as "Beth Carlson",
then on a subsequent call identifies herself as "This is Beth Carlson", there is a
fair chance that Beth Car/son will be identified in the second instance. This
would not be possible if an isolated word recognizer were used.
In recent years the use of iconic imagery has been methodically employed in
many computer systems and is found to be a significant improvement over
traditional text-oriented interfaces [Smith 82].
While the use of ideograms is
perhaps undesirable [Lippman 84], they do provide a visual way of presenting
abstract information. Conversing with a computer should be accomplished in a
natural fashion without the use pictograms, and this is certainly possible with
voice interaction. To interact with a graphical display, however, there must be an
image of some sort which can be seen and selected.
underlying software structure of the system will permit other
input/output devices and alternative forms of multi-media mail, such as a written
or voice annotation over a video message, to be easily integrated into the PITS.
Only minor modifications would be necessary to increase the capabilities of this
system because device polling and user feedback is controlled from a few low
level routines.
Outgoing calls would enable the distribution of messages to the system
owner, his acquaintances, or even to other personal telecommunications
systems. The telephone network of the future will be entirely digital, the most
likely channel being high-bandwidth optical fiber. When this time arrives, the
transfer of speech and images between PITS-like personal computers seems
highly likely.
Single boards containing a digital signal processing chip are now available
for personal computers. These devices are capable of performing most of the
audio processing associated with the PITS such as DTMF decoding and
generation, and speech coding for speech recognition and reduced storage. A
software configurable system based on hardware such as this permits maximum
flexibility of resources, and is potentially more useful than a collection of
individual devices (e.g. speech coders and recognizers) which hang off a
telephone line.
The PITS is more than an intelligent answering machine; it combines multimodal communications and merges them into a single form so that voice and
data messages are not considered separate entities. The interface is responsive,
allowing messages to be accessed by voice, keypad, or touch screen with
simultaneous verbal and graphical feedback. A personal computer forms a new
type of telecommunications environment around its owner, gathering and
disseminating information from several information networks.
explores -and
successfully demonstrates mechanisms for unified voice and gesture interaction
through a diverse range of communication tasks.
The interface design
philosophy provides a cogent framework for the future influx of conversational
computers into man-machine interaction.
Chris Schmandt has been my partner in research, office-mate, and friend
since the inception of this project. We have spent many long hours brainstorming
and writing code, this time has always been interesting, educational, and a lot of
Bender was
providing programming
invaluable in
tools and
encouragement throughout my two years at the Architecture Machine Group. His
fine sense of form and color helped shape and improve the design and layout of
the PITS graphical interface.
Andy Lippman, director of the lab, supported me on this and other projects.
He provided inspiration and many ideas, but always encouraged me to think and
further develop concepts on my own.
Marc Spehlmann designed, built, and continuously improved the telephone
interface hardware used in this project.
Dave Chen took pictures when I couldn't be behind the camera and provided
advice concerning the layout of this document.
The Architecture Machine is a unique and very special place, it has become
more of a home than my apartment in Boston. I thank everyone in the group for
all their help, friendship, and great ideas. Special thanks to my fellow graduate
students, particularly Ken Carson, Steve Gano, and Eric Brown for their sense of
quality, thoroughness, and ability to understand the big picture in designing
intelligent systems.
[Abelson 84]
Harold Abelson and Gerald Sussman.
Structure and Interpretation of Computer Programs.
MIT Press and McGraw-Hill, 1984.
[Allen 76]
Jonathon Allen.
Synthesis of Speech from Unrestricted Text.
Transactions of the IEEE 4:433-442, 1976.
[Allen 81]
Jonathon Allen.
Linguistic-based Algorithms Offer Practical Text-to-speech Systems.
Speech Technology 1(1), Fall, 1981.
[Arons 84]
Barry Arons.
Educational and Industrial Television 16(6), June, 1984.
[Baker 81]
Janet M. Baker.
How to Achieve Recognition: A Tutorial/Status Report on Automatic
Speech Recognition.
Speech Technology 1(1):30-43, Fall, 1981.
[Baker 83]
Caren Hope Baker.
Voice Access to Electronic Mail.
Bachelor's thesis, MIT, June, 1983.
[Bayer 83]
D. L. Bayer and R. A. Thompson.
An Experimental Teleterminal - The Software Strategy.
The Bell System Technical Journal 62(1):121-144, January, 1983.
[Bergland 82a]
G. D. Bergland.
Experiments in Telecommunications Technology.
IEEE Communications Magazine 20(6):4-14, December, 1982.
[Bergland 82b]
G. D. Bergland, W. T. Hartwell, and G. W. Smith.
1A Voice Storage System: Prologue.
The Bell System Technical Journal 61(5):815-819, May-June, 1982.
[Boyle 81]
Thomas Boyle.
The Design and Implementation of a Crash Proof File System.
Bachelor's thesis, MIT, June, 1981.
[Bruckert 84]
Ed Bruckert.
A New Text-to-speech Product Produces Dynamic Human Quality Voice.
Speech Technology 2(2):114-119, Jan/Feb, 1984.
[Cagle 71]
W.B. Cagle, R.R. Stokes, and B.A. Wright.
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