Menu navigation method for user of audio headphones

Menu navigation method for user of audio headphones
US 20140198917A2
(19) United States
(10) Pub. N0.: US 2014/0198917 A2
(43) Pub. Date:
Jul. 17, 2014
(12) Patent Application Publication
REPUBLICATION
JAISIMHA et al.
(54)
MENU NAVIGATION METHOD FOR USER
OF AUDIO HEADPHONES
Publication Classi?cation
(51) 1111.0.
(71) Applicant: Panasonic Automotive Systems
H04R 5/04
Company of America, Division of
Panasonic Corporation of North
CPC ...................................... .. H04R 5/04 (2013.01)
America, PEACHTREE CITY, GA (U S)
USPc
(72) Inventors: SHREE JAISIMHA, SENOIA, GA
381/17
ABSTRACT
A method of operating an audio system having ?rst and
second sources includes outputting a ?rst audio signal from
the ?rst source on ?rst and second speakers. In response to a
listener input, the ?rst audio signal and a second audio signal
from the second source are output simultaneously on the ?rst
and second speakers. The ?rst signal is output from each of
the ?rst and second speakers such that the ?rst signal is
perceived by a listener to originate from a ?rst direction
toward the listener. The second signal is output from each of
the ?rst and second speakers such that the second signal is
perceived by the listener to originate from a second direction
(21) Appl. N0.: 13/713,462
Filed:
.......................................................... ..
(57)
(US); MOHAMMED REZA KANJI,
BRAMPTON, ONTARIO (CA); LI
LIAN LAY, URBANA, MD (US);
JOHN MORRIS, FAYETTEVILLE,
GA (US); JAMES P. REEFE,
PEACHTREE CITY, GA (US)
(22)
(2006.01)
(52) U.S.Cl.
Dec. 13, 2012
Prior Publication Data
toward the listener. The second direction is offset at least
ninety degrees from the ?rst direction.
(65) US 2013/0216045 A1 Aug. 22, 2013
702
700
/
receive ?rst and second monaural signals associated
with the ?rst and second sources, respectively
704
l
transform the ?rst and second monaural signals into respective ?rst
and second stereo signals, the ?rst and second stereo signals each being
spatialized to a respective angle of trajectory, the ?rst and second stereo signals
each having a left channel and a right channel
|
l
perform asynchronous sample rate conversion on the left and
right channels of each of the first and second stereo signals
l
l
combine the left channels of the ?rst and second
stereo signals into a combined left channel signal
l
combine the left channels of the first and second
stereo signals into a combined right channel signal
l
,
adjust a gain of the combined left channel signal
i
adjust a gain of the combined right channel signal
L
simultaneously output the gain-adjusted combined
l
l
left channel signal and the gain-adjusted combined right channel
signal on the ?rst and second speakers
706
\708
Patent Application Publication
Jul. 17, 2014 Sheet 1 0f6
60 deg
60 deg
(left audio) >
(right audio)
Human head
240 deg
240 deg
FIG. 1
Human head
FIG. 2
US 2014/0198917 A2
Patent Application Publication
Jul. 17, 2014 Sheet 2 0f 6
US 2014/0198917 A2
TunerlF
FrontEndlC
AF
27/
\26
AF
22
Sample Hold
XM or
DAB
Module
~—IZS—-
DSP
30
/
\
32
24
/
Microcontroller
\
User
34/
FIG. 3
Display
36
Patent Application Publication
Jul. 17, 2014 Sheet 3 0f 6
US 2014/0198917 A2
Left Channel
’
\38
/
42/
sound A
40
—‘ )
6+180
H (W, 6) ejwh (
)
/
Left Channel
46/
Audio of
sound B
44
Right Channel
H (w, @) e'jw‘h‘M”)
\48
52/
253,123
50
H (w, <9) 6"”? (‘9)
/
Right Channel
56/
54
FIG. 4B
Audio of
sound 8
Patent Application Publication
Jul. 17, 2014 Sheet 4 0f6
US 2014/0198917 A2
58
42/
Left Channel
Audio of
sound A
Asynchronous Sample Rate
Converter to 44.1 kHz
66
60
/
Left Channel
Audio of
sound 8
Asynchronous Sample Rate
Converter to 44.1 kHz
FIG.
Gain
5A
62
Right Channel
45/
Audio of
sound A
/
Asynchronous Sample Rate
Converter to 44.1 kHz
64
Right Channel
56/
Audio of
sound B
72
/
Asynchronous Sample Rate
Converter to 44.1 kHz
FIG.
5B
Gain
Patent Application Publication
Jul. 17, 2014 Sheet 5 0f 6
US 2014/0198917 A2
600
output a ?rst audio signal from a ?rst
source on ?rst and second speakers
provide a listener input
\602
\_
604
505
in response to the listener input, output the ?rst audio signal and a
second audio signal from a second source simultaneously on the ?rst and
second speakers, the ?rst signal being output from each of the
?rst and second speakers such that the ?rst signal is perceived by a listener
to originate from a ?rst direction toward the listener, the
second signal being output from each of the ?rst and second
speakers such that the second signal is perceived by the listener to
originate from a second direction toward the listener, the second direction
being offset at least ninety degrees from the ?rst direction
enable the listener to audiny navigate through menu sections
of the second source while continuing to listen to the ?rst source
/
608
FIG. 6
Patent Application Publication
Jul. 17, 2014 Sheet 6 0f 6
US 2014/0198917 A2
702
700
/
receive ?rst and second monaural signals associated
with the ?rst and second sources, respectively
704
transform the ?rst and second monaural signals into respective ?rst
and second stereo signals, the ?rst and second stereo signals each being
spatialized to a respective angle of trajectory, the ?rst and second stereo signals
each having a left channel and a right channel
perform asynchronous sample rate conversion on the left and
right channels of each of the ?rst and second stereo signals
combine the left channels of the ?rst and second
stereo signals into a combined left channel signal
combine the left channels of the first and second
stereo signals into a combined right channel signal
adjust a gain of the combined left channel signal
adjust a gain of the combined right channel signal
simultaneously output the gain-adjusted combined
left channel signal and the gain-adjusted combined right channel
signal on the ?rst and second speakers
FIG. 7
706
\708
Jul. 17, 2014
US 2014/0198917 A2
MENU NAVIGATION METHOD FOR USER
OF AUDIO HEADPHONES
CROSS-REFERENCE TO RELATED
APPLICATION
[0001] This application is a continuation of US. patent
application Ser. No. 12/322,258, ?led on Jan. 30, 2009 which
is currently under allowance, the disclosure of which are
hereby incorporated by reference in their entirety for all pur
poses.
[0011] The invention may provide an effective, novel and
feasible way of enhancing the overall user experience in
navigating within and across a multitude of audio sources
which may be available to a user of headphones in a rear seat
audio application. The invention may further provide a new
dimension to user navigation by utiliZing three-dimensional
audio transforms and multi-instance decoders.
[0012] The invention comprises, in one form thereof, a
method of operating an audio system having ?rst and second
sources, including outputting a ?rst audio signal from the ?rst
source on ?rst and second speakers. In response to a listener
COPYRIGHT NOTICE
input, the ?rst audio signal and a second audio signal from the
[0002] Portions of this document are subject to copyright
protection. The copyright owner does not object to facsimile
reproduction of the patent document as it is made available by
the US. Patent and Trademark Of?ce. However, the copy
right owner reserves all copyrights in the software described
herein. The following notice applies to the software described
and illustrated herein: Copyright © 2008, Panasonic Automo
second speakers. The ?rst signal is output from each of the
?rst and second speakers such that the ?rst signal is perceived
tive Systems Company of America, All Rights Reserved.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to audio menu naviga
tion, and, more particularly, to audio menu navigation when
second source are output simultaneously on the ?rst and
by a listener to originate from a ?rst direction toward the
listener. The second signal is output from each of the ?rst and
second speakers such that the second signal is perceived by
the listener to originate from a second direction toward the
listener. The second direction is offset at least ninety degrees
from the ?rst direction.
[0013] The invention comprises, in another form thereof, a
method of operating an audio system having ?rst and second
sources, including outputting a ?rst audio signal from the ?rst
source on the ?rst and second speakers. In response to a
listener input, the ?rst audio signal and a second audio signal
using headphones.
from the second source are simultaneously output on the ?rst
[0005] 2. Description of the Related Art
[0006] With the number of audio sources available in
today’ s multimedia systems increasing rapidly, the number of
and second speakers. The ?rst signal is output from each of
the ?rst and second speakers such that the ?rst signal is
source based selection options in cars is also increasing. At
the present time, some of the source selection options in the
car audio applications in the case of rear seat audio applica
tions include the following sources: XM or Sirius (satellite
perceived by a listener to originate from a ?rst direction
toward the listener. The second signal is output from each of
the ?rst and second speakers such that the second signal is
perceived by the listener to originate from a second direction
toward the listener. The listener is enabled to audibly navigate
audio), CD, DVD, AM or FM, AUX, Phone, Onstar (US.
market segment only), USB, High De?nition Radio (US.
market segment only) and DAB (European market segment
through menu selections of the second source while continu
ing to listen to the ?rst source.
only).
and the source selection has not yet arrived to make the
navigation easier within and across the navigation sources for
thereof, a method of operating an audio system, including
receiving ?rst and second monaural signals associated with
?rst and second sources, respectively. The ?rst and second
monaural signals are transformed into respective ?rst and
second stereo signals. The ?rst and second stereo signals are
each spatialized to a respective angle of trajectory. The ?rst
the end user.
and second stereo signals each have a left channel and a right
[0008]
Consider the case of a single source with USB.
channel. Asynchronous sample rate conversion is performed
Music navigation through the USB ?ash drive source for
example requires the user to be able to traverse one song at a
time for the user to decide which song he would like to select.
This is a rather cumbersome process, especially with com
pressed audio wherein the songs can number over one hun
on the left and right channels of each of the ?rst and second
stereo signals. The left channels of the ?rst and second stereo
signals are combined into a combined left channel signal. The
right channels of the ?rst and second stereo signals are com
bined into a combined right channel signal. Gains of the
dred depending on the ?ash storage content within the USB
drive.
combined left channel signal and the combined right channel
signal are adjusted. The gain-adjusted combined left channel
[0007]
Currently there is no known innovative system that
enables a savvy user to make selections of audio sources more
ef?ciently. A bridge between better human factor engineering
[0009]
Accordingly, what is neither anticipated nor obvi
[0014]
The invention comprises, in yet another form
signal and the gain-adjusted combined right channel signal
ous in view of the prior art is a method of enabling a user to
are simultaneously output on the ?rst and second speakers.
more ef?ciently navigate menus in applications having more
[0015] An advantage of the present invention is that a user
may temporarily listen to and navigate through a second
than one audio source.
SUMMARY OF THE INVENTION
[0010]
The present invention may provide a method for a
user to listen to two separate sources of audio content simul
audio source while continuing to listen to a ?rst audio source
that is on a commercial break. The user may then go back to
listening to the ?rst audio source exclusively when the com
mercial break ends.
taneously. Further, the user may navigate the menu of either
[0016]
audio source while listening to both audio sources simulta
innovative solution for radios with rear seat audio to improve
their navigation ability across and within sources and repre
neously.
Another advantage is that the invention provides an
Jul. 17, 2014
US 2014/0198917 A2
sents a paradigm shift in user navigation in line with advances
in Human Machine Interaction in car audio systems.
embodiments are chosen and described so that others skilled
BRIEF DESCRIPTION OF THE DRAWINGS
in the art may utilize its teachings.
[0026] Referring now to the drawings, and particularly to
FIG. 1, there is shown a schematic diagram of spatial audio of
[0017] The above-mentioned and other features and objects
of this invention, and the manner of attaining them, will
two stereo audio sources projected to a user who is wearing
audio headphones, such as in the rear seat of a motor vehicle.
become more apparent and the invention itself will be better
The invention may utilize three-dimensional audio effects to
produce spatial localization effects so that up to two sources
understood by reference to the following description of
embodiments of the invention taken in conjunction with the
accompanying drawings, wherein:
[0018] FIG. 1 is a schematic diagram illustrating one
embodiment of spatial audio as employed in the present
invention;
may be projected simultaneously, thereby enabling faster user
selection. In the embodiment of FIG. 1, spatialization of sixty
degrees is utilized.
[0027] Multiple audio outputs may be achieved within the
same source (in one embodiment, USB ?ash drive) at the
same time through multi-instance decoders in a multi
[0019] FIG. 2 is a schematic diagram illustrating inter-aural
differences calculated for source in the azimuthal plane
threaded operating system based embedded system. The
de?ned by two ears and a nose.
multi-instance decoders may allow for producing two simul
[0020] FIG. 3 is a block diagram illustrating one embodi
ment of a radio system of the present invention.
taneous audio sources at the same time in a multi-threaded
[0021]
FIGS. 4A and 4B are block diagrams illustrating
framework.
[0028] A ?ash ?le system may be utilized to allow direct
transformation of mono-signals into stereo signals according
access of data recorded in separate ?ash areas. Utilization of
to embodiments of methods of the invention.
multi-instance decoders each run on a separate thread in a
[0022] FIGS. 5A and 5B are block diagrams illustrating
embodiments of an asynchronous sample rate conversion
process of the present invention.
[0023] FIG. 6 is a ?ow chart illustrating one embodiment of
a method of the present invention for operating an audio
multi-threaded operating system environment makes this
system.
passenger wearing headphones.
[0024] FIG. 7 is a ?ow chart illustrating another embodi
ment of a method of the present invention for operating an
[0030] In one embodiment, a stereo signal is converted into
a mono-signal and then is transformed back to a spatialized
stereo signal. The stereo signal may be transformed into a
mono-signal by dividing the sum of the left channel and the
audio system.
DETAILED DESCRIPTION
possible.
[0029] With the use of multi-instance decoders, it is pos
sible to play two songs at the same time. It is also possible to
simultaneously project the two audio sources to the rear seat
right channel by two (i.e., (Left Channel+Right Channel)/ 2).
[0025] The embodiments hereinafter disclosed are not
intended to be exhaustive or limit the invention to the precise
forms disclosed in the following description. Rather the
Additional details of sampling rates of different input sources
considered in one embodiment of an algorithm of the present
invention are provided in the following table:
Potential
Input
Sources
Method to convert to
in Car
Audio
Systems
Stereo or Mono
Typical Sampling
Determination
Rates
Mono input signal
into spatial
Algorithm
FM
Utilization of Pilot
15 kHz
If Stereo, convert to
Signal. IfPilot Signal
Mono input by using
exists in the 38 kHz
the formula: Output =
offset, then it is a
(Left PCM + Right
stereo signal.
PCM)/2. If Mono
signal is received in
PM band, utilize it as
input directly.
AM
Assumed mono if C—
9 or 10 kHz
Assume as Mono and
Quam stereo is not
input it to the
utilized. Typically C—
Quam is not commonly
algorithm.
utilized.
USB
Stereo or mono
Variable rate from as
audio
determination from MP3
low as 32 kbps up to
If Stereo, convert to
Mono input by using
header information
128 kbps, information
on sampling rate
the formula: Output =
(Left PCM + Right
de?ned in
PCM)/2. If Mono
compression algorithm signal is received,
header information
utilize it as
128 kbps
If Stereo, convert to
input directly.
DAB
Audio
Stereo or mono
determination from MP2
Mono input by using
header information
the formula: Output =
(Left PCM + Right
Jul. 17, 2014
US 2014/0198917 A2
3
-continued
Potential
Input
Sources
Method to convert to
in Car
Audio
Systems
Mono input signal
into spatial
Algorithm
Stereo or Mono
Typical Sampling
Determination
Rates
PCM)/2. If Mono
signal is received,
utilize it as
input directly.
XM
Stereo or mono
128 kbps
If Stereo, convert to
Audio
determination header
Mono input by using
information prior to
the formula: Output =
going through
compressed audio
decoder
(Left PCM + Right
PCM)/2. If Mono
signal is received,
utilize it as
input directly.
CD
Check the Table Of
44.1 kHz
Audio
Contents Information of
Mono input by using
If Stereo, convert to
the recorded track
the formula: Output =
(Left PCM + Right
PCM)/2. If Mono
signal is received,
utilize it as
input directly.
The present invention may, across disparate sources,
user is listening to a source and is interrupted by a commercial
rede?ne the source selection pushbutton or key which is pres
ently on current rear seat audio (RSA) systems in the auto
motive market. The source selection key may enable the user
[003 1]
to the commercial, the user actuates a control on the audio
system in order to listen to a second audio source while
in the present audio source. Not wanting to listen exclusively
to navigate across sources one source at a time.
continuing to listen to the ?rst audio source. For example, the
[0032]
user ?ips a switch or presses a key on the HMI to enable the
Across sources, for example, audio source naviga
tion across disparate sources such as XM and FM audio may
require the user to press the source key to go across the
sources with the limitation that the user can listen to only one
audio source at any point in time before he decides which
source program to listen to. The term “disparate sources” may
refer to audio sources that can be decoded independently of
each other. For example, FM audio output can occur at the
same time as XM audio output as the two have independent
demodulators and separate antenna sources with no shared
spatial audio, i.e., the dual audio source mode. In the spatial
audio, the user is able to select and listen to a new source but
he is still able to simultaneously listen to his previously
selected source. The user may tune back to the previously
selected source once the commercial ends. While the user is
audibly browsing the other station, the original source can be
deceased in volume (e.g., 3 dB or 6 dB) by a user-selected
menu selection. Thus, the new source may be played louder
than the original source while both sources are being played
dependency that could prevent both audio sources from being
simultaneously.
output at the same time. The present invention may enable the
user to listen to two disparate sources at different angles of
arrival in a headphone set and select the audio source he
would like to listen to in collaboration with a Human Machine
source may be greater than that of the original source, the new
[0035]
Although the overall perceived loudness of the new
source is not necessarily played louder than the original
source on both speakers. For example, the new source may be
Interface system.
played almost entirely on one of the speakers, while the
[0033] The Human Machine Interface (HMI) of a car audio
system may utilize alpha-blending and screen-on-screen
techniques to overlap two separate sources together with one
of loudness between the speakers.
in the foreground and the other in the background. Alpha
blending is a convex combination of two colors allowing for
transparency effects in computer graphics. These video
original source may be played with a more even distribution
[0036] The human hearing system is able to perceive the
locations of, i.e., localize, sources of sound through interaural
level differences (ILD) and interaural time differences (ITD).
sources typically are independent of each other, and the user
ILD comes into play when the intensity of the source signal
may be able to View a second source while listening to a ?rst
reaching one ear differs from that reaching the other car. ILD
source. The present invention may be applied to alpha-blend
occurs due to diffraction when the sound waves diffract
ing and screen-on-screen techniques to audibly complement
these video techniques.
against the human head.
[0034]
Consider the case where a user is listening to a
radio may be expressed in decibels. ILD dominates over ITD
source that is interrupted by a commercial on that station and
would like to browse another source selection with the inten
tion of returning soon to his original source selection. Other
with increasing frequency content of the input signal due to
the fact that scattering by the human head increases rapidly
with increasing frequency. For instance, the wavelength of
than user menu navigation, one embodiment of a method of
sound at 500 Hz is 69 cm, which is four times the average
diameter of the human head. FIG. 2 illustrates interaural level
the present invention may be applied in scenarios in which the
[0037]
The interaural level differences with regard to the
Jul. 17, 2014
US 2014/0198917 A2
differences calculated for source in the azimuthal plane
Interaural time difference (ITD), on the other hand,
[0045] Microcontroller 22 may in turn link, as at 36, to a
touch screen HMI display 34, which enables the user to select
the source that he wants to listen to. HMI display 34 in
applies for localization of sounds having frequencies below
particular may provide the source selection with display cues
500 Hz and is the result of the difference in arrival times of the
which may highlight the spatial angle.
sound waveform at the two ears. A phase difference corre
[0046] Within the software architecture inside microcon
troller 22, operation is conducted in a multithreaded system.
de?ned by two ears and the nose.
[0038]
sponds to an interaural time difference (ITD) of At:3(a/ c)*sin
6, where 6 is the azimuthal (left-right) angle illustrated in
The application may run on a thread on main microcontroller
FIG. 2, a is the radius of the human head and c is the speed of
sound (34400 cm/sec).
[0047]
[0039]
by-sample based system. To avoid this, a ?xed ping pong
buffer may be utilized to collect the samples and process the
The human binaural system thus performs spatial
localization using ILD and ITD cues. In summary, the binau
ral system is sensitive to amplitude cues from ILD above 500
Hz. These ILD cues become large and reliable for frequencies
above 3000 Hz, while ITD cues work well for frequencies
below 1500 Hz. For a sine tone of frequency such as 2000 Hz,
neither cue works well. As a result, human localization ability
tends to be poor for signals in this frequency range.
[0040] Starting from the approximation of the head as a
rigid sphere that diffracts a planar wave, the head shadow or
ITD can be:
[0041] w:c/a, where c is the speed of sound and a is the
radius of the head.
(1(6):1.05+0.95 cos(180*0/150)
The position of the zero varies with the azimuth angle 6. The
formula above may be translated into a stable in?nite impulse
response (IIR) digital ?lter using bilinear transformation:
It may be dif?cult for DSP 24 to operate in a sample
data in a frame. The input signal can be either a stereo or a
monotone signal. If the input is a stereo signal, the algorithm
may require the input signal to be converted to a monotone
input signal before processing.
[0048]
The conversion of a stereo signal to a monotone, i.e.,
monaural, signal before processing may be achieved as
described in the table provided and discussed above. The
software may ascertain the type of source at play based on the
current mode.
[0049] The sampled sources may then go through a spatial
?lter. Mono-signals may again be transformed into stereo
signals (but this time spatialized to the angle of trajectory)
after going through the spatial ?lter de?ned in FIGS. 4a and
4b. In FIG. 4a, a monaural sound input A 38 of a particular
source is input to a spatial ?lter 40 de?ned by H(w,6)e_j“"h(0)
to produce Left Channel Audio 42 of soundA; and is input to
a spatial ?lter 44 de?ned by H(w,6)e_j""h(e+180) to produce
Right Channel Audio 46 of sound A. Similarly, in FIG. 4b, a
monaural sound input B 48 of a particular source is input to a
spatial ?lter 50 de?ned by H(w,6)e_jMh(e+180) to produce Left
Channel Audio 52 of sound B; and is input to a spatial ?lter 54
de?ned by H(w,6)e_j‘””h(e) to produce Right Channel Audio
[0042]
Referring to FIG. 3, there is shown one embodiment
of a vehicle rear seat radio system 20 of the present invention
including a microcontroller 22 that may be used to process
56 of sound B.
[0050] Combining the different sources may be tricky, as
the above table shows that each source may have a different
sampling rate. Utilizing a priori information regarding the
input source selection sampling rate based on the above table,
user input. A digital signal processor (DSP) 24 may be used to
provide audio demodulation of the air-borne IF input signal.
DSP 24 may also be used to provide quality information
the present invention may include asynchronous sample rate
converters 58, 60, 62, 64 (FIG. 5) to assist in the mixing
parameters to the main microcontroller 22 via a serial com
process.
munication protocol such as I2C. The quality information
[0051]
parameters may include multipath, adjacent channel noise,
of adders 66, 68. Adder 66 combines the Left Channel por
tions of sounds A and B. Similarly, adder 68 combines the
Right Channel portions of sounds A and B. The common
factor sampling rate in the embodiment of FIG. 5 is 44.1 kHz,
and ?eld strength. DSP 24 may rely on a Tuner IC 26 to
perform the front end RF demodulation and the gain control.
Tuner IC 26 may also output the Intermediate Frequency to
DSP 24 where the Intermediate Frequency may be demodu
lated and processed. Tuner IC 26 may further provide a gain
to the IF (Intermediate Frequency) of up to 6 dBuV prior to
forwarding the signal to DSP 24. Communication between
Converters 58, 60, 62, 64 may be disposed upstream
which may advantageously provide signal ?delity and good
resolution.
[0052]
Gain blocks 70, 72 may compensate for the spectral
amplitude scaling involved during asynchronous sample rate
Tuner IC 26 and DSP 24, as indicated at 27, may be via a serial
conversion. Asynchronous sample rate conversion typically
communication protocol such as I2C, which may operate at
involves upsampling followed by downsampling polyphase
400 kbps.
?lter utilization.
[0043] An antenna system 28 may be communicatively
coupled to Tuner IC 26. Antenna system 28 may be in the
and Sound B are recorded at the same sampling rate, the
form of a passive mast, or an active mast of phase diversity, for
following logic may be employed:
example.
[0044] DSP 24 may provide signal quality parameteriza
tion of demodulated tuner audio and may make it available to
microcontroller 22 via a serial bus 32. In one embodiment,
serial communication bus 32 is in the form of a 400 kbps high
[0053] In the simplest example context, assuming SoundA
Output Right Channel Audio:0.5(Rig_ht Channel of
Sound B)+O.5(Right Channel of Sound A)
Output Left Channel Audio:0.5(Le? Channel of
Sound B)+O.5(Left Channel of Sound A)
speed I2C. A radio data system (RDS) interrupt line 30 may
[0054] Asynchronous Sample Rate Converters 58, 60, 62,
also be provided between DSP 24 and microcontroller 22.
64 may include an Audio Codec ’97 to provide ?exibility.
Jul. 17, 2014
US 2014/0198917 A2
That is, the Audio Codec ’97 may support different output
sample rates, although in the disclosed embodiment the out
put is 44.1 kHZ. The data may be processed through ?lters 40,
44, 50, 54 and output to a high priority task which runs the
Audio Codec ’97.
[0055] Provided below is an example of simulation model
spatialized in the left 60 degree aZimuthal plane should not
exhibit a stronger spectral content on its right channel else it
may hamper the algorithm’s ability to spatialize the signal
properly at the correct direction.
[0058] During use, the listener may be listening to a ?rst
source of an audio signal, such as AM radio, FM radio, CD,
code in Matlab programming language which implements
satellite radio, DVD, AUX, telephone, Onstar, USB, high
logic. This simulation code may be run on an Intel Centrino
de?nition radio, or DAB, for example. At some point in time,
Processor (x86 target).
the listener may want to check out a second audio source
while still continuing to monitor the ?rst audio source to
which he is listening. For example, the listener may be listen
A = wavread(‘sesame. wav’);
maxA = max(A);%Compute the maximum amplitude Within signal
A
maxB = max(B);%Compute the maximum amplitude Within signal
B
maxinorm = max(maxA,maxB); %Find the maximum across
signals A and B
A = Nmax(maxinorm);%Normalize the Input signal to the
maximum
B = B/max(maxinorm);%Normalize the Input signal to the
maximum
%A and B are stereo signals both at same sampling rates
AL=hs?lter(60,8000,A); %Apply ?lter on left channel of Signal A
AR=hs?lter(240,8000,A); %Apply ?lter on right channel of Signal
A
BL=hs?lter(240,8000,B); %Apply ?lter on left channel of Signal
B
BR=hs?lter(60,8000,B); %Apply ?lter on right channel of Signal
B
for i=l:l :length(A(l :10000))
y(i,l)=0.5*AL(i) + O.5*(BL(i)); %Combine the 2 signals onto one
output left channel audio
y(i,2)=0.5*AR(i) + 0.5*(BR(i)); %Combine the 2 signals onto one
output right channel audio
end
%y-spatial audio which contains 2 audio sources each coming at
60deg angle to azimuth.
[0056] Provided below is an example of a spatial ?lter
algorithm in Matlab. The spatial ?lter models the head
shadow and ITD effects, the shoulder echo and the pinna
re?ections.
ing to a ?rst audio source in the form of radio when the radio
broadcast goes into a commercial break. Rather, than listen to
the commercials, the listener may press a pushbutton, ?ip a
switch, or vocalize a command instructing the audio system
to go into a dual source mode in which the listener may
continue to listen to the ?rst audio source while interacting
with the second audio source.
[0059] In one embodiment, the listener may interact with
the second audio source by navigating through menu selec
tions of the second audio source while still listening to the ?rst
source. Such menu selections may include radio frequencies,
songs, albums and artists. The navigation of the menu selec
tions of the second audio source may include scanning
through and listening to audio of the menu selections in
sequence while simultaneously continuing to listen to the ?rst
audio source. The navigation of the menu selections of the
second audio source may additionally include scanning
through and viewing the sequence of menu selections on
display 34. In another embodiment, the navigation of the
menu selections of the second audio source includes only
viewing the menu selections on display 34 without addition
ally listening to the second audio source.
[0060] It is to be understood that the listener is not required
to perform menu navigation in the second audio source. That
is, the listener may simply listen to the second audio source
simultaneously with the ?rst audio source without perform
ing any menu navigation. Similarly, while in the dual source
mode, the listener may or may not perform menu navigation
in the ?rst audio source.
[0061] The user may return to the single source mode when
he is ready to do so, such as when he hears that the commer
cial break on the ?rst audio source is completed. Speci?cally,
the listener may again press a pushbutton, ?ip a switch, or
vocalize a command instructing the audio system to go into a
single source mode in which the listener may go back to
listening to the ?rst audio source exclusively.
[0062] One embodiment of a method 600 of the present
invention for operating an audio system is illustrated in FIG.
6. In a ?rst step 602, a ?rst audio signal is output from a ?rst
source on ?rst and second speakers. That is, an audio signal
from an audio source such as a radio or CD may be audibly
output on the two speakers of a pair of headphones. The
speakers may be associated with the left ear and right ear,
respectively, of the listener wearing the headphones.
[0063] Next, in step 604, a listener input may be provided.
[0057] It is possible for the sampled audio source to pan the
audio from either left to right or right to left. If a spatial ?lter
For example, the listener may press a pushbutton, ?ip a
switch, or issue a voice command instructing the audio sys
is applied to these input signals it makes it di?icult for the end
user to distinguish between the panned audio signal and the
spatial effects that may be introduced. In order to prevent the
tem to enter a dual audio source mode.
user perception of the spatialized angle from being affected,
from a second source simultaneously on the ?rst and second
the input signal may be converted to a monotone before being
applied to the spatial ?lter. For example, a signal meant to be
speakers, the ?rst signal being output from each of the ?rst
and second speakers such that the ?rst signal is perceived by
[0064] In a next step 606, in response to the listener input,
the ?rst audio signal and a second audio signal are output
Jul. 17, 2014
US 2014/0198917 A2
a listener to originate from a ?rst direction toward the listener,
[0069]
the second signal being output from each of the ?rst and
second speakers such that the second signal is perceived by
stereo signals are combined into a combined left channel
In step 708, the left channels of the ?rst and second
signal. That is, adder 66 combines the left channels of sounds
the listener to originate from a second direction toward the
A and B into a combined left channel signal.
listener, the second direction being offset at least ninety
[0070]
degrees from the ?rst direction. In one embodiment, in
stereo signals are combined into a combined right channel
response to the listener switching to the dual audio source
mode, a ?rst audio signal from a radio, for example, and a
signal. That is, adder 68 combines the right channels of
second audio signal from a CD, for example, are output
simultaneously on the speakers of the headphone. The signal
from the radio may be output from each of the headphone
speakers such that the radio signal is perceived by a listener to
originate from a direction generally to the left of the listener,
for example. The signal from the CD may be output from each
of the headphone speakers such that the CD signal is per
ceived by the listener to originate from a direction generally
to the right of the listener, for example. Thus, the direction
from which the CD is perceived to originate may be offset
from the direction from which the radio is perceived to origi
nate by at least ninety degrees. That is, the perceived direc
tions from which the two sounds approach the listener may be
offset from one another by approximately between ninety and
one hundred eighty degrees.
[0065] In a ?nal step 608, the listener is enabled to audibly
navigate through menu selections of the second source while
continuing to listen to the ?rst source. That is, while in the
dual audio source mode, the listener may provide further
inputs that instruct the CD player to advance to the next song
on the CD, or to the next CD. The song or CD menu selections
may be presented to the listener audibly on the speakers
and/ or visually on display 34.
[0066] Another embodiment of a method 700 of the present
invention for operating an audio system is illustrated in FIG.
7. In a ?rst step 702, ?rst and second monaural signals asso
ciated with the ?rst and second sources, respectively, are
received. For example, ?rst and second audio sources, such as
a radio and a CD player, may each output a respective stereo
signal. Depending upon the speci?c audio source, the table
above describes how these stereo signals may be transformed
into monaural signals associated with the radio and CD
player, respectively.
[0067]
Next, in step 704, the ?rst and second monaural
signals are transformed into respective ?rst and second stereo
signals, the ?rst and second stereo signals each being spatial
ized to a respective angle of trajectory, the ?rst and second
stereo signals each having a left channel and a right channel.
In the embodiment of FIGS. 4a and 4b, the ?rst and second
monaural signals from the radio and CD player are each
transformed into left and right channel stereo signals by spa
tial ?lters 40, 44, 50 and 54. Further, spatial ?lters 40, 44, 50
and 54 may spatialized each of the stereo signals to a respec
tive angle of trajectory. More particularly, by controlling the
relative loudnesses and/or phases of the left and right chan
nels, spatial ?lters 40, 44, 50 and 54 may provide the stereo
signals with characteristics that cause the human binaural
system to perceive the stereo signals as coming from any
desired directions in the aZimuthal plane intersecting the ears.
[0068] In a next step 706, asynchronous sample rate con
version is performed on the left and right channels of each of
the ?rst and second stereo signals. That is, as shown in FIG. 5,
In step 710, the right channels of the ?rst and second
sounds A and B into a combined right channel signal.
[0071] Next, in step 712, a gain of the combined left chan
nel signal is adjusted. In the embodiment of FIG. 5, for
example, the combined left channel signal from adder 66 is
fed into gain block 70 where the signal’s gain is adjusted.
[0072] In a next step 714, a gain of the combined right
channel signal is adjusted. In FIG. 5, speci?cally, the com
bined right channel signal from adder 68 is fed into gain block
72 where the signal’s gain is adjusted.
[0073]
In a ?nal step 716, the gain-adjusted combined left
channel signal and the gain-adjusted combined right channel
signal are simultaneously output on the ?rst and second
speakers. That is, the gain-adjusted combined left channel
signal from gain block 70 and the gain-adjusted combined
right channel signal from gain block 72 are simultaneously
output on the two speakers of the headphones, corresponding
to the listener’s left and right ears.
[0074] The present invention has been described herein as
applying to headphone speakers. However, it is to be under
stood that the invention may more generally be applied to any
multiple speaker audio system.
[0075] While this invention has been described as having
an exemplary design, the present invention may be further
modi?ed within the spirit and scope of this disclosure. This
application is therefore intended to cover any variations, uses,
or adaptations of the invention using its general principles.
Further, this application is intended to cover such departures
from the present disclosure as come within known or custom
ary practice in the art to which this invention pertains.
What is claimed is:
1. A method of operating an audio system having ?rst and
second sources and ?rst and second speakers, the method
comprising the steps of:
receiving ?rst and second monaural signals associated with
the ?rst and second sources, respectively;
transforming the ?rst and second monaural signals into
respective ?rst and second stereo signals, the ?rst and
second stereo signals each being spatialized to a respec
tive angle of traj ectory, the ?rst and second stereo signals
each having a left channel and a right channel;
performing asynchronous sample rate conversion on the
left and right channels of each of the ?rst and second
stereo signals;
combining the left channels of the ?rst and second stereo
signals into a combined left channel signal;
combining the right channels of the ?rst and second stereo
signals into a combined right channel signal;
adjusting a gain of the combined left channel signal;
adjusting a gain of the combined right channel signal; and
simultaneously outputting the gain-adjusted combined left
channel signal and the gain-adjusted combined right
channel signal on the ?rst and second speakers.
2. The method of claim 1 comprising the further step of
asynchronous sample rate converters 58, 60, 62, 64 may be
employed to perform asynchronous sample rate conversion
converting respective original stereo signals from the ?rst and
on the left and right channels of both sound A and sound B.
second sources into the ?rst and second monaural signals.
Jul. 17, 2014
US 2014/0198917 A2
3. The method of claim 1 comprising the further step of
enabling the listener to audibly navigate through menu selec
tions of the second source while continuing to listen to the
?rst source.
4. The method of claim 1 wherein the transforming step
includes inputting the ?rst and second monaural signals into
respective ?rst and second spatial ?lters.
5. The method of claim 1 wherein the asynchronous sample
rate conversion includes upsampling followed by utilization
of a downsampling polyphase ?lter.
6. The method of claim 1 wherein the adjusting steps
include compensating for spectral amplitude scaling associ
ated with the asynchronous sample rate conversion.
7. The method of claim 1 wherein the ?rst signal is output
from each of the ?rst and second speakers such that the ?rst
signal is perceived by a listener to originate from a ?rst
direction toward the listener, the second signal being output
from each of the ?rst and second speakers such that the
second signal is perceived by the listener to originate from a
second direction toward the listener, the second direction
being offset at least ninety degrees from the ?rst direction.
8. A method of operating an audio system having ?rst and
second sources and ?rst and second speakers, the method
comprising the steps of:
receiving ?rst and second monaural signals associated with
the ?rst and second sources, respectively;
transforming the ?rst and second monaural signals into
respective ?rst and second stereo signals, the ?rst and
second stereo signals each being spatialized to a respec
tive angle of traj ectory, the ?rst and second stereo signals
each having a left channel and a right channel;
performing asynchronous sample rate conversion on the
left and right channels of each of the ?rst and second
stereo signals;
combining the left channels of the ?rst and second stereo
signals into a combined left channel signal;
combining the right channels of the ?rst and second stereo
signals into a combined right channel signal; and
simultaneously outputting the combined left channel sig
nal and the combined right channel signal on the ?rst and
second speakers.
9. The method of claim 8 comprising the further steps of:
adjusting a gain of the combined left channel signal; and
adjusting a gain of the combined right channel signal,
wherein the simultaneously outputting step comprises
simultaneously outputting the gain-adjusted combined
left channel signal and the gain-adjusted combined right
channel signal on the ?rst and second speakers.
10. The method of claim 8 comprising the further step of
converting respective original stereo signals from the ?rst and
second sources into the ?rst and second monaural signals.
11. The method of claim 8 comprising the further step of
enabling the listener to audibly navigate through menu selec
tions of the second source while continuing to listen to the
?rst source.
12. The method of claim 8 wherein the transforming step
includes inputting the ?rst and second monaural signals into
respective ?rst and second spatial ?lters.
13. The method of claim 8 wherein the asynchronous
sample rate conversion includes upsampling followed by uti
lization of a downsampling polyphase ?lter.
14. The method of claim 8 wherein the adjusting steps
include compensating for spectral amplitude scaling associ
ated with the asynchronous sample rate conversion.
15. The method of claim 8 wherein the ?rst signal is output
from each of the ?rst and second speakers such that the ?rst
signal is perceived by a listener to originate from a ?rst
direction toward the listener, the second signal being output
from each of the ?rst and second speakers such that the
second signal is perceived by the listener to originate from a
second direction toward the listener, the second direction
being offset at least ninety degrees from the ?rst direction.
16. A method of operating an audio system having ?rst and
second sources and ?rst and second speakers, the method
comprising the steps of:
receiving ?rst and second monaural signals associated with
the ?rst and second sources, respectively;
transforming the ?rst and second monaural signals into
respective ?rst and second stereo signals, the ?rst and
second stereo signals each having a left channel and a
right channel;
performing sample rate conversion on the left and right
channels of each of the ?rst and second stereo signals;
combining the left channels of the ?rst and second stereo
signals into a combined left channel signal;
combining the right channels of the ?rst and second stereo
signals into a combined right channel signal;
adjusting a gain of the combined left channel signal;
adjusting a gain of the combined right channel signal; and
simultaneously outputting the gain-adjusted combined left
channel signal and the gain-adjusted combined right
channel signal on the ?rst and second speakers.
17. The method of claim 16 wherein the ?rst and second
stereo signals are each spatialized to a respective angle of
trajectory.
18. The method of claim 16 wherein the sample rate con
version comprises asynchronous sample rate conversion.
19. The method of claim 16 comprising the further step of
enabling the listener to audibly navigate through menu selec
tions of the second source while continuing to listen to the
?rst source.
20. The method of claim 16 wherein the ?rst signal is
output from each of the ?rst and second speakers such that the
?rst signal is perceived by a listener to originate from a ?rst
direction toward the listener, the second signal being output
from each of the ?rst and second speakers such that the
second signal is perceived by the listener to originate from a
second direction toward the listener, the second direction
being offset at least ninety degrees from the ?rst direction.
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