Sound reproduction system
United States Patent [191
[11]
4,349,697
Skabla
[45]
Sep. 14, 1982
dimensional phased sound that simulates the perfor
[54] SOUND REPRODUCTION SYSTEM
[76] Inventor: Joseph Skabla, 2601 S.
mance of live music in an acoustically superior music
Kingshighway, St. Louis, Mo. 63139
[21] Appl. No.: 134,338
[22] Filed:
[51]
Mar. 26, 1980
Int. Cl.3 ............................................. .. H04R 3/14
[52]
U.S. Cl.
[58]
Field of Search ................. .. 179/1 G, 1 GP, 1 D,
...............
. . . . . . ..
1
[56]
V
179/1 D;
179/1 J
179/1 J; 84/125
References Cited
U.S. PATENT DOCUMENTS
2,837,597
6/1958
Lubow ........................... .. 179/1 GP
3,657,480 4/1972 Cheng et a1.
4,039,755
8/1977
Berkovitz ...................... .. 179/1 J X
FOREIGN PATENT DOCUMENTS
174223 3/1953 Fed. Rep. of Germany 179/1 GP
865578
4/1961
United Kingdom ........... .. 179/1 GP
Primary Examiner—Joseph A. Popek
Attorney, Agent, or Firm—Gravely, Lieder & Woodruff
[57]
hall includes a signal divider which separates the audio
signal into dimensions, that is into high, low, and inter
mediate frequency components. Each component after
being ampli?ed powers a separate loud speaker so that
the sound emitted by the three speakers is in phase with
the audio signal. In addition, each component is di
rected through a delay device where it is delayed on the
order of 20-300 milliseconds, with the delay for each of
the three components being different. The delayed sig
nal components, after being ampli?ed, power separate
loud speakers so that the sound which emerges from
these speakers is the same as the sound produced at the
other speakers, but is slightly out of phase. Moreover,
the magnitude of the delay varies between the high,
low, andintermediate frequency ranges with the delay
being greatest for the high frequency range. The overall
effect is to prolong the initial in phase sound and
thereby signi?cantly enhance the brilliance and richness
of the reproduced music. Indeed, the reproduced sound
closely simulates the acoustics of a ?ne music hall.
ABSTRACT
A system for converting an audio signal into a three
16 Claims, 1 Drawing Figure
1
4,349,697
SOUND REPRODUCTION SYSTEM
BACKGROUND OF THE INVENTION
This invention relates in general to the reproduction
of sound and more particularly to an apparatus and
process for simulating in reproduced music the acousti
cal characteristics of ?ne music halls.
Music when performed out-of-doors lacks richness
and is often described as being dead, and while this
music may not be unpleasant to the average listener, the
listener nonetheless realizes that the music is de?cient in
some respect. More often than not he attributes the
de?ciency to the musicians. On the other hand, the
acoustical characteristics of a few music halls through
out the world impart a high degree of brilliance and
richness to music performed in them, and consequently
these music halls can flatter the performances of other~
wise mediocre musicians. Carnegie Hall in New York
City has perhaps the best acoustics for performing both
choral and instrumental music. _London, Stockholm,
Vienna, Belgrade, and Moscow also have very ?ne
music halls.
2
cally superior music hall. Another object is to provide a
system and process of the type stated which is suitable
for reproducing recorded music, irrespective of the
recording medium or the number of channels in which
the music is recorded. An additional object is to provide
a system and process of the type stated that is simple in
construction and relatively inexpensive to construct. A
further object is to provide a system and process that
effectively simulates the acoustics of fine music halls
and can be altered to simulate performances in different
music halls. Still another object is to provide a system
and process of the type stated that produces three di
mensional phased sound. These and other objects and
advantages will become apparent hereinafter.
The present invention is embodied in an apparatus
including means for dividing an audio signal into a plu
rality of components with each component containing
frequencies of a different range, ?rst speaker means for
converting the components of the signal into audible
sounds, delay means for delaying the individual compo
nents, and second speaker means for converting the
delayed components into an audible sound that is
slightly out of phase with the sound emitted from the
Generally speaking, music performed indoors sounds
far superior to the same music performed outdoors, and 25 ?rst speaker means. The delay is such that the out of
phase sounds produced at the second speaker means
this difference is easily detected even by those who are
simulate the reflective effects that occur within a ?ne
not well versed in music, for the indoor music has a
music hall. The invention also resides in the process of
richness and brilliance that the outdoor music lacks.
The difference is attributable to the acoustics of the
dividing the audio signal into components, converting
enclosure in which the music is performed. For exam 30 the components into audible sound, delaying each of the
ple, a musical sound when produced within an enclo
components, and also converting the delayed compo
sure, will not terminate immediately, even though the
nents into a second audible sound that is slightly out of
sound is actually terminated at its source. Quite to the
phase with the ?rst audible sound. The invention also
contrary, the sound tends to “hang on” since it contin
consists in the parts and in the arrangements and combi
ues to re?ect off of the surfaces of the enclosure. The 35 nations of parts hereinafter described and claimed.
result is a decay which varies with frequency in that the
DESCRIPTION OF THE DRAWINGS
high frequency sounds decay slower, or in other words
hang on longer, then the low frequency sounds. In con
The single FIGURE of the drawing schematically
trast to an echo, the re?ected sound follows the initial
illustrates the sound reproducing apparatus of the pres
sound so closely that it cannot be distinguished as a
ent invention in the form of a block diagram.
separate sound. The sound-prolonging characteristics
DETAILED DESCRIPTION
both the size and shape of the enclosure and also the
The sound system A of this invention is particularly
materials from which the enclosure is constructed, par
adapted for reproducing music, irrespective of whether
ticularly those materials that form the surface areas 45
it is recorded or live, and like practically all sound re
within the enclosure. Indeed, some materials even reso
production
systems, converts an audio signal S carrying
nate, causing the listener to feel enveloped in sound, this
many frequencies into audible sound. The signal S may
being particularly true of the wood panelled music
of any enclosure are to a large measure dependent upon
rooms of Europe.
be derived from any of a number of sources, but irre~
and brilliance of live music, at least when compared
with live music performed in a music hall of superior
acoustics. Indeed, even when the recorded music is
its low, intermediate, and high frequency components.
Each of these components, after being ampli?ed, is
Recorded music never seems to possess the richness 50 spective of its source, the signal S is divided to separate
converted to primary audible sounds through a suitable
derived from a performance in a very ?ne music hall
speaker, with this conversion occuring instantaneously
and is reproduced over the ?nest playback equipment, it
the development of high ?delity, stereophonic, and
so that the primary sounds are in phase with the signal
S. In addition, each of the components of the signal S
passes through a delay device where the component is
delayed in time and thereby placed out of phase with
even quadraphonic recordings, as well as highly sophis
audio signal S. The delays for the various components
ticated playback equipment for handling these im
proved recordings. In spite of these developments, it
differ. The delayed components are then converted into
secondary audible sounds, which are the same as the
still seems to lack brilliance and richness. Attempts to
improve the quality of recorded music have resulted in
seems impossible to capture the acoustics of a ?ne music
hall to the fullest extent.
SUMMARY OF THE INVENTION
primary sounds, except that they are slightly out-of
phase with the primary sounds and may be of lesser
intensity. Moreover, the delay is so short that the sec
65 ondary sounds are not discernible as such. Nevertheless,
One of the principal objects of the present invention
is to provide a system and process for reproducing
they provide the reproduced music with a brilliance and
richness that is not available even with the most sophis
musical sounds as if they were performed in an acousti
ticated recording and playback equipment. Indeed, the
3
4,349,697
overall effect simulates the acoustics of a ?ne music
hall.
The audio signal S that is converted into audible
sound by the system A is electrical in nature and carries
a multitude of frequencies corresponding the frequen
cies in the music that is to be reproduced. The audio
signal S is derived from a source 2 which may be any of
the primary sound in-and-of itself lacks somewhat in
richness and brilliance as is somewhat typical of repro
duced sound.
a wide variety of equipment currently available for
producing such signals. For example, the source 2 may
be a machine for playing disk-type records. In this in
stance, the signal S is generated at a stylus which fol
lows the groove of a record disk, and through the piezo
Each signal component Sh, Sm, and S; that is pro
duced by the signal divider 4 is also directed to a unit 20
containing three separate delay devices-namely a
delay device 22 for the high frequency component 5],,
another delay device 24 for the intermediate frequency
electric effect converts undulations in that groove into
an electrical signal S. The source 2 may also be a ma
chine for playing magnetic tapes, and in this instance
the signal S is derived from a magnetic reproducing
4
of the components Sh, Sm, and S1are reproduced at the
speakers 12, 14 and 16 instantaneously with their ap
pearance in the original signal S at the source 2. The
result is a three dimensional primary sound containing
the entire range of frequencies in the audio signal S, but
component Sm, and still another delay device 26 for the
15
head past which the tape moves.
The source 2 is not limited exclusively to playback
equipment, for it may also be the tuner of radio receiver
low frequency component 5]. The delay devices 22, 24,
and 26 delay the signal components 5],, Sm, and 5],
respectively, so that the signal components 5],, Sm, and
8], upon emerging from the unit 20 are somewhat out of
the multiple channels or paths along which these signals
phase with the original signal S and its undelayed com
ponents Sh, Sm, and S1. The delay in each of the devices
22, 24, and 26 is normally less than one second, usually
ranging between 20 and 300 milliseconds. Moreover,
the delay varies between the devices 22, 24, and 26,
with the delay in the devices 22 and 24 tending to be
longer than the delay in the device 26 for the low fre
quency component 5]. The delays produced in the unit
pass may be combined into a single channel within the
system A so that the system A actually producesthe
audible sound from a single audio signal S. The signal S,
20 are tailored to the particular acoustic effect one is
seeking to simulate, such as the acoustics of a well
known music hall. For example, to simulate the acous
or even a microphone in front of a performing group at
a remote location. Furthermore, the signal S should be
monophonic, in which case it is transmitted to the sys
tem A through a single electrical path or channel.
Where multiple audio signals are available such as in the
case of stereophonic or even quadraphonic recordings, 25
irrespective of its derivation, will usually contain volt
30
age ?uctuations at a multitude of frequencies represent
tics of Carnegie Hall in New York City, the delay in
high frequency device 22 should be about 150 millisec
onds; the delay in the intermediate frequency device 24
should be about 105 milliseconds; and the delay in the
low frequency device 26 should be about 45 millisec
ing and corresponding to the various frequencies at
which the music is performed.
The system A includes a signal divider 4, which is
actually an electronic ?lter that divides the signal S into 35 onds. Since one may wish to simulate the acoustics of
three different components-namely a high frequency
different music halls, the unit 20 should be capable of
component 5],, an intermediate or midrange frequency
being easily detached and replaced with another unit
component Sm, and a low frequency component S1. The
having different delays in its delay devices 22, 24, and
high frequency component 5;, contains all those fre
26. This same end may be achieved by making the indi
quencies in the original signal that are above a predeter 40 vidual devices 22, 24, and 26 adjustable so that their
mined frequency such as 2000 Hz, while the low fre
time delays may be varied.
quency component contains all frequencies that are
The delayed signals 8],, Sm, and 8] upon emerging
below a predetermined frequency such as 200 Hz. Of
from the unit 20 each pass into another preampli?er 30
course, the intermediate frequency component Sm con
where they are individually ampli?ed and then on to
tains all frequencies between the high and low fre 45 another main ampli?er 32 where they are ampli?ed still
quency components S}, and S1, and in the case of the
further.
previous limits will range between 200 and 2000 Hz.
The delayed and ampli?ed signal components Sh, Sm,
Actually the high frequency component 5;, may have
and S1 are directed to a separate speaker unit 34 contain
frequencies as high as 2000 Hz, whereas the low fre
ing three separate speakers, namely a high frequency
quency component S1may have frequencies as low as 20 50 speaker or tweeter 36, a midrange speaker 38, and a low
Hz.
frequency speaker or woofer 40. More speci?cally, the
Each signal component Sh, Sm, and S1then passes into
a preampli?er 6 where it is separately ampli?ed and
delayed high frequency signal component S}, is directed
to the tweeter 36 where it is converted into an audible
sound that is the same as the sound produced by the
then on to a main ampli?er 8 where it is separately
ampli?ed still further.
55
tweeter 12, but is slightly out of phase with the sound
Beyond the main ampli?er 8 is a speaker unit 10 con
emerging from the tweeter 12 and perhaps at a lower
sisting of at least three speakers—namely a high fre
quency speaker or tweeter 12, a midrange speaker 14,
and a low frequency speaker or woofer 16. The high
intensity. The time span between the reproduction of
frequency component Sh, after being ampli?ed in the
the same sounds by the two tweeters 12 and 36 is of
course the time delay of the delay device 22, and that
60 delay is so short that the two sounds cannot be individu
main ampli?er 8 is directed to the tweeter 12. Similarly,
ally distinguished. Indeed, the delayed sound from the
the ampli?ed intermediate frequency component Sm is
directed to the midrange speaker 14, while the ampli?ed
low frequency component S1 is directed to the woofer
16. Thus, the speaker unit 10 produces an audible sound
from the three components Sh, Sm, and S1 of the original
audio signal S, and that sound is in phase with the origi
nal signal S. In other words, the individual frequencies
tweeter 36 causes the initial high frequency sound to
remain alive or hang on so-to-speak, thereby adding
richness to the initial sound without appearing as an
65
echo. Similarly, the delayed signal component Sm pow
ers the midrange speaker 38, causing it to emit a sound
that is the same as the sound produced at the midrange
speaker 14, only it is delayed by the amount of the time
5
4,349,697
delay in the delay device 24 and is of slightly lower
intensity. Again the delayed sound from the speaker 38
prolongs the initial midfrequency sound from the
speaker 14. Likewise, the delayed low frequency com
ponent S1, after being ampli?ed, is directed to the
woofer 40 where it is reproduced as the same sound that
is emitted from the woofer 16, only the sound at the
woofer 40 is delayed by the time delay of the circuit 26
and has lower intensity. Thus, the sound emitted by the
woofer 40 imperceptibly extends the initial in phase
sound at the woofer 16. In essence, the speaker unit 34
emits a secondary sound that contains the same full
range of frequencies as the primary sound emitted from
6
into low frequency, high frequency, and intermediate
frequency components, with the low frequency compo
nent containing frequencies primarily below the inter
mediate frequency component, the high frequency com
ponent containing frequencies primarily above the in
termediate frequency component, and the intermediate
frequency component containing frequencies primarily
above the low frequency component and primarily
below the high frequency component; ?rst speaker
means for converting the components of the signal into
primary audible sounds; delay means for delaying the
individual components of the signal, with the high and
intermediate frequency components being delayed
the speaker unit 10, but‘ is of less intensity and out of
longer than the low frequency component; and second
phase, with the delay depending on and varying be 15 speaker means for converting the delayed components
tween the frequency ranges. The end result is a three
into secondary audible sounds, the delay causing the
dimensional phased sound.
secondary sounds emerging from the second speaker
Each delay device 22,-24, or 26 may constitute noth
means to be out of phase with respect to the primary
ing more than thin steel wire that is preferably wound
sounds emerging from the ?rst speaker means, the delay
into a spiral. Resistance-type heating element wire is 20 being such that the out of phase secondary sounds im
suitable for this purpose. The delay devices 22, 24, and
perceptibly prolong the primary sound such that the
26 may also be electronic circuits containing diodes,
combined primary and secondary sounds simulate the
crystals, transistors, or other electronic devices.
acoustics of a ?ne music hall.
The two speaker units 10 and 34 should be generally
2. An apparatus according to claim 1 wherein the
at the same location, and indeed, the speakers of each 25 delay means delays each of the signal components for a ‘
may be intermixed. For example, excellent results are
different time.
obtained when the two tweeters 12 and 36, the two
3. An apparatus according to claim 2 and further
midrange speakers 14 and 38, and the two woofers 16
comprising ?rst ampli?er means for amplifying the
and 40 are arranged together in pairs.
undelayed components and second ampli?er means for
Since the music that is derived from the audio signal
amplifying the delayed components.
S is reproduced both instantaneously through the
4. An apparatus according to claim 3 wherein the
speaker unit 10 as a primary sound and with slight delay
second ampli?er means ampli?es the delayed compo
through the speaker unit 34 as a secondary sound, the
nents to a lesser extent than the ?rst ampli?er means
overall effect is one of brilliance and richness, since the
ampli?es the primary components so that the secondary
secondary sound emerging from the speaker unit 34
sounds emerging from the second speaker means are at
prolongs the sound derived from the speaker unit 10.
a lower intensity than corresponding primary sounds
Thus, the sounds from the three speakers 12, 14, and 16
emerging from the ?rst speaker means.
of the speaker unit 10 tend to hang on and resemble the
5. An apparatus according to claim 1 wherein the first
kaleidoscope of sound prevelant in a good music hall. In
speaker means includes a separate loud speaker for each
short, the sound acquires a three dimensional phased. 40 component of the signal that produces the primary
effect, because each speaker 36, 38, 40 of the speaker
sounds.
unit 34 is out of phase with its corresponding speakers 6. An apparatus according to claim 5 wherein the
12, 14, and 16 in the speaker unit 10 by a different time
second speaker means includes a separate loud speaker
span. This reproduces the acoustical effect of a ?ne
for each delayed component of the signal that produces
music hall where the high frequency sounds have a 45 the secondary sounds.
greater life span than the midfrequency sounds, and the
7. An apparatus according to claim 6 wherein the
mid-frequency sounds have a greater life span than the
low frequency sounds.
By varying the time delays in the three frequency
loud speakers of the ?rst and second speaker means are
located in close proximity to each other.
8. An apparatus according to claim 1 wherein the
ranges it is possible to simulate the acoustics of different 50 delay means delays the high frequency component
music halls. The acoustic properties of such halls are to
longer than the intermediate frequency component and
a large measure dependent upon their size and con?gu
delays the intermediate frequency component longer
ration, and when only these parameters are taken into
than the low frequency component.
consideration, it is possible to calculate the delays nec
9. An apparatus according to claim 1 wherein the
essary for the delay devices 22, 24, and 26 in order to 55 delay means delays each of the signal components be
simulate the acoustics of such a music hall, or more
speci?cally simulate the sound heard by one sitting
generally in the balcony midway between the stage and
tween 20 and 300 milliseconds.
10. An apparatus according to claim 1 wherein the
low frequency component contains frequencies primar
the back wall and midway between the sidewalls.
ily below about 200 Hz, the high frequency component
This invention is intended to cover all changes and 60 contains frequencies primarily above about 2000 Hz,
modi?cations of the example of the invention herein
and the intermediate frequency component contains
chosen for purposes of the disclosure which do not
frequencies primarily between about 200 Hz and 2000
constitute departures from the spirit and scope of the
Hz.’
invention.
11. A process for reproducing musical sounds from
What is claimed is:
65 an audio signal containing a wide range of frequencies
1. An apparatus for producing audible sound from an
corresponding to the frequency of the music that is to
electrical audio signal containing various frequencies,
said apparatus comprising: means for dividing the signal
be reproduced, said process comprising: dividing the
audio signal into low frequency, high frequency, and
7
4,349,697
intermediate frequency components with the low fre
8
12. The process according to claim 11 wherein each
signal component is delayed for a different duration.
13. The process according to claim 11 wherein the
secondary sound derived from the delayed components
quency component containing primarily frequencies
below the intermediate frequency component, the high
frequency component containing frequencies primarily
5
above the intermediate frequency component, and the
are at a lower intensity than the primary sounds derived
intermediate frequency component containing frequen
from the primary components.
cies primarily above the low frequency component and
primarily below the high frequency component; con
verting the signal components into a primary audible
high frequency component in the delayed signal is de
layed longer than the intermediate frequency compo
sound; delaying each of the signal components for a
short duration with the high and intermediate fre
layed longer than the low frequency component.
7 14. The process according to claim 11 wherein the
nent, and the intermediate frequency component is de
15. The process according to claim 11 wherein the
quency components being delayed longer than the low
frequency component; and converting the delayed sig
nal components into a secondary audible sound which is 15
substantially the same as the primary sound, but is
slightly out of phase with respect to the primary sound,
the delay being such that the secondary sound prolongs
low frequency component contains frequencies primar
ily below about 200 Hz, the high frequency component
contains frequencies primarily above about 2000 Hz,
and the intermediate frequency component contains
frequencies primarily between about 200 Hz and about
2000 Hz.
16. The process according to claim 11 wherein each
the primary sound and simulates the acoustics of a ?ne
music hall, so that the primary and secondary sounds 20 of the components is delayed between 20 and 300 milli
seem as if they are the result of a musical performance
in a ?ne music hall.
seconds.
ll
25
30
35
45
50
55
60
I‘
III
I!
III
UNITED‘STATES PATENT AND TRADEMARK OFFICE
PATENT N0. :
CERTIFICATE
4,349,697
DATED
September 14, 1982
mvemoms) ;
F
‘
Joseph Skabla ‘
It is certified that error appears in the above-identified patent and that ‘said Letters Patent is hereby
corrected as shown below:
Column 3, line 49, "2000 Hz" should be "20000 Hz".
ignt an
Thirlierh
eaie tt'e
of November I 982
ISEAL]
A nest:
GERALD .B. MOSSINGHOFF I
AIM-?ing Officer
('ommissioner afPalems and Trademarks
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