Exhibit 1

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 1 of 14 PageID #: 261
United States Patent 

USOO713 0430B2 

(12) (10) Patent No.: US 7,130,430 B2 

Milsap (45) Date of Patent: Oct. 31, 2006 

(54) PHASED ARRAY SOUND SYSTEM 6,373,955 B1 4/2002 Hooley 

6,434,239 B1 8, 2002 DeLuca 

(76) Inventor: Jeffrey P. Milsap, 2O7 Canterbury Ct., 2001/OOOT591 A1* T/2001 Pompei - - - - - - - - - - - - - - - - - - - - - - 381,111 

Cambridge, WI (US) 53523 2001/0043652 A1 1 1/2001 Hooley s 2002fOO 12442 A1 1/2002 Azima et al. 

c - r 2002/0106093 A1 8/2002 AZima et al. 

(*) Notice: Sibi tO , distic th still 2002/0131608 A1* 9, 2002 Lobb et al. ................. 381,111 

p l S. so: CC UC 2003/0031333 A1 2/2003 Cohen et al. ............... 381 (303 

OTHER PUBLICATIONS 

(21) Appl. No.: 10/024,159 “An Audio Spotlight creates a Personal Wall of Sound”, Jennifer 8. 

1-1. Lee, New York Times on the Web www.nytimes.com, (C) 2001 New (22) Filed: Dec. 18, 2001 York Times Company. 

O O "Time-Reversed Acoustics', Mathias Fink, Scientific American, (65) Prior Publication Data Nov. 1999, pp. 91-97. 

US 2003/O1854O4 A1 Oct. 2, 2003 “Out of Thin Air, Trudy E. Bell, IEEE Spectrum, Feb. 1997. 

“A Sound idea? Grad student's audio spotlight has companies' ears'. 

(51) Int. Cl. snifer 8. Lee, Milwaukee Journal Sentinel, May 28, 2002, pp. Gl, 

H04B 3/00 (2006.01) 

(52) U.S. Cl. ............................ 381/77; 381/79; 381/80; * cited by examiner 

381/82 Primary Examiner Brian T. Pendleton 

(58) Field of Classification Search 381/79.so s' (74) Attorney, Agent, or Firm—Stiennon & Stiennon 

See application file for complete search history. (57) ABSTRACT 

(56) References Cited 

U.S. PATENT DOCUMENTS 

4,359,944 A 11, 1982 Stiennon 

4,515,997 A 5/1985 Stinger, Jr. 

4,789,801 A 12/1988 Lee 

5,020, 155 A * 5/1991 Griffin et al. ................. 381,79 

5,109,416 A 4, 1992 Croft 

5,404,406 A 4, 1995 Fuchigami et al. 

5,521,981 A 5/1996 Gehring 

5,596,649 A 1, 1997 Liu 

5,668,884 A 9/1997 Clair, Jr. et al. 

5,781,645 A 7, 1998 Beale 

5,889,870 A 3, 1999 Norris 

5,949,894 A 9, 1999 Nelson et al. 

5,974,152 A 10/1999 Fujinami 

6,016,353 A 1/2000 Gunness 

6,163,613 A 12/2000 Cowans 

6,263,083 B1* 7/2001 Weinreich .................... 381.97 

An array of speakers are fed from a single source of audio 

frequency Sound but each speaker transmits the Sound 

delayed by an amount which is determined by the distance 

between a particular speaker and a selected region in space, 

so that Sound from each speaker constructively adds at the 

selected region in space. A Sufficiently large number of 

speakers are employed so that when Sound reaches a region 

in space at the same moment in time the audio Volume will 

be increased substantially over Sound in regions where there 

is not constructive interference. This simple technique 

allows audio frequency Sound to be heard in only selected 

regions within the room or other auditory space. Multiple 

regions with multiple soundtracks can be created by simul 

taneously playing variously delayed soundtracks over each 

of the speakers in the array. 

19 Claims, 3 Drawing Sheets 

3) 52 

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U.S. Patent Oct. 31, 2006 Sheet 1 of 3 US 7,130.430 B2 

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U.S. Patent 

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U.S. Patent Oct. 31, 2006 Sheet 3 of 3 US 7,130,430 B2 

Audio Audio 

SOurce 94 SOurce 94 

97 

Volume 108 Volume 

Control Control 

Didital 

Adder 

104 

DIA Fig. 3 

106 

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US 7,130,430 B2 

1. 

PHASED ARRAY SOUND SYSTEM 

CROSS REFERENCES TO RELATED 

APPLICATIONS 

None. 

STATEMENT AS TO RIGHTS TO INVENTIONS 

MADE UNDER FEDERALLY SPONSORED 

RESEARCH AND DEVELOPMENT 

None. 

BACKGROUND OF THE INVENTION 

The present invention relates to systems for reproducing 

Sound in general and to systems which can control Sound 

production to localized regions in particular. 

A typical Sound system performs two functions: ampli 

fying sound and reproducing sound with a given level of 

clarity or intelligibility within a particular room, auditorium, 

hall or other space. Sound may be either audio frequency 

Sound, SubSonic sound, or ultrasonic Sound. The audio 

frequency sound falls within the range of 15 Hz to 20,000 

HZ, the range generally of human hearing, with SubSonic 

frequencies being those below 15 Hz, and ultrasonic fre 

quencies being those above 20,000 Hz. 

Recently new capabilities have led to research in sound 

systems which could have the potential to produce Sound 

which is contained within a beam, or which is aimed at a 

particular point or listener. Such systems open up the pos 

sibility of providing different audio stimulus to different 

people occupying the same room, museum, or lecture hall. 

Such a system might also provide more realistic stereo 

without using headphones by providing a separate audio 

input to each ear of a listener. 

One approach proposed by Joe Pompei while a student at 

MIT, involves generation of ultrasonic sound which distorts 

in a predictable way so that the distortions produce audio 

frequency Sound. Starting with the desired audio frequency 

Sound it is mathematically possible to predict the ultrasonic 

beam which will produce the desired audio frequency sound. 

By Such means Pompei is able to generate an audio spotlight 

of Sound. 

Another proposed approach is to use an acoustic time 

reversal mirror. Such systems have been developed by Mathias Fink at Ecole Superieure de Physique et de Chimie 

Industrielles de la Ville de Paris. A time-reversal mirror is a 

concept known from optics where it is known to be possible 

to construct a mirror which sends light reflected therefrom 

directly backwards so that the lightwaves appear to be 

reversed in time. Thus light emitted from a point when 

reflected in a phase conjugate, or time-reversal mirror, 

returns to the emitting point. To look into a time-reversal 

mirror is to see only the light emitted from the pupil which 

is gazing into the mirror. In a similar way, an acoustic time 

reversal mirror returns sound to the source that emitted the 

Sound. This returning Sound returns identically to that emit 

ted, even if the path between the sound source and the 

time-reversal mirror involves many reflections, distortions, and dispersions. At least in theory, the time reversal process 

could be used to focus Sound at a particular location so that 

different sounds would be heard by different people. 

A wide variety of audio systems attempt to provide more 

realistic Sound by providing an array of speakers which 

produce the effect that the Sound appears to come from a 

particular direction or source and Such systems are described 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

2 

in U.S. Pat. No. 5,521,981 to Gehring or U.S. Pat. No. 

5.974,152 to Fujinami. More generally, any stereo, quadra 

phonic, or Surround sound system uses multiple speakers to 

produce Sound which is more realistic. 

However, none of the foregoing systems has produced a 

cost-effective system for providing Sound which can only be 

heard in a localized region. What is needed is an apparatus 

and method for producing audible sounds which are local 

ized so that multiple listeners can be provided with unique 

audio input without the use of headphones. 

SUMMARY OF THE INVENTION 

The Sound reproduction system of this invention employs 

an array of speakers to produce audio frequency sound. The 

speakers are fed from a single audio Source, but each speaker 

transmits Sound delayed by an amount which is related to the 

distance between a particular speaker and a selected point or 

region in space. In addition the amplitude of the Sound 

output by each speaker may also be proportional to the 

distance between the particular speaker and a selected point 

or region in space. In one embodiment the audio output of 

each speaker can be below the audible threshold. An array of speakers is arranged on the ceiling or walls or even 

randomly distributed within the room. With such an arrange 

ment the output from any given speaker cannot be heard. 

However, if each speaker has its output delayed such that 

even though the Sound from each speaker in the array travels 

a different distance, the sound from all the speakers never 

theless reaches a single point or region in space at the same 

moment in time, the audio volume will be increased in 

proportion to the square of the number of speakers employed 

in the array. Thus, with a sufficient number of speakers producing inaudible Volume levels of Sound, at a particular region the sound will be readily audible. This simple tech 

nique allows audio frequency sound to be heard in only 

selected regions within the room or other auditory space. 

This method achieves the result that the wave front from 

each speaker arrives at the target at the same time and 

roughly in phase. Due to Superposition, the amplitudes of the 

wave-fronts will add algebraically. Sound intensity or vol 

ume is a function of the square of the signal amplitude, 

therefore very significant sound intensities at the target can 

be achieved for reasonable sized arrays. 

A time varying audio stream of Sound is digitized into a 

multiplicity of discrete digital samples similar to those used 

in digital recording systems such as those used in producing 

compact discs or digital audio tape. 

The speed of Sound in air, although varying with air 

temperature, is approximately 1,000 feet per second (fps). 

For a room having a maximum linear dimension of 40 feet, 

Sound can travel from any speaker to any point in the room 

in 0.04 seconds. If sound is digitized at 44 kilohertz, the 

standard for most digital sound preproduction—approxi 

mately 1,760 sound samples are produced during 0.04 

seconds. 

If we now consider an array of speakers we can calculate 

the distance between each speaker in the array and a selected 

point in the room. A computer or similar device is used to 

continuously store 1,760 sequential sound samples, in 1760 

storage registers, which are being incremented by one 

sample every 44,000 of second, corresponding to the Sound 

sample interval. We can produce a digital sample stream for 

generating an audio drive signal for a particular speaker 

which is delayed by any amount within the 0.04 seconds, simply by reading out the value of a particular memory 

every sample cycle, i.e. every 44,000 of a second from the 

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US 7,130,430 B2 

3 

particular memory which corresponds to the selected time 

delay. The time delay is selected to correspond to the 

distance between a particular speaker and the point or region 

in space where it is desired to create a clearly audible Sound. 

In particular, the distance between a particular speaker and 

the point or region in space is subtracted from the distance 

of the furthest speaker which has zero time delay and the 

result is divided by 1000 (the speed of sound) and multiplied 

by 44,000 which will give the number of the sound storage register, out of the 1760 sound storage registers, which will 

produce a digital output corresponding to an audio signal 

which has been delayed by a length of time such that all 

Sound signals reach the same point at the same time. 

It is an object of the present invention to provide a Sound 

system which can produce one or more localized regions of 

audible sound. 

It is another object of the present invention to produce a 

Sound system where different persons within the same room 

can hear distinctly different Soundtracks and cannot hear any 

soundtrack but the one directed at them. 

It is a further object of the present invention to provide a 

Sound system which does not produce clearly audible Sound 

except within selected regions. 

It is a yet further object of the present invention to provide 

a Sound system where an array of speakers operating at a 

first sound level produces sound at selected points or regions 

in space at least an order of magnitude louder than the first 

sound level. 

Further objects, features and advantages of the invention 

will be apparent from the following detailed description 

when taken in conjunction with the accompanying drawings. 

BRIEF DESCRIPTION OF THE DRAWINGS 

FIG. 1 is pictorial perspective view of the sound repro 

duction system of this invention. 

FIG. 2 is a schematic view of how the sound reproduction 

system of FIG. 1 produces a discrete region of sound which 

is spaced from the speakers which generate a sound pattern. 

FIG. 3 is a schematic view of how sound from different 

audio Sources is combined and transmitted through a single speaker to produce sound output which will contribute to 

forming multiple discrete regions of Sound which are sepa 

rated in space. 

FIG. 4 is a schematic plan view of a ceiling tile incorpo rating a multiplicity of discrete speakers which form part of 

the sound reproduction system of FIG. 1. 

DESCRIPTION OF THE PREFERRED 

EMBODIMENTS 

Referring more particularly to FIGS. 1-4, wherein like 

numbers refer to similar parts, an array 20 containing a 

multiplicity of audio speakers 22 acting as audio frequency 

Sound Sources, is positioned on the ceiling 24 of a room or 

gallery 26 of a museum. As shown in FIGS. 1 and 4, the 

ceiling 24 consists of multiple tiles 28 each tile containing 

a sub-array 30 of speakers 22 which are connected by data 

transmission lines 32 and power Supply lines 34, to each 

other so that power and data can be communicated between 

the tiles 28. In a typical arrangement of speakers 22, 

hundreds to over one thousand discrete speakers are used to 

create a sound reproduction system 36 with the ability to 

produce audio signals which are only audible, or Substan 

tially more audible, within selected discrete regions 40. The 

speakers 22 of the array 20 are driven so as to produce 

regions 40 of constructive interference, as set out in greater 

5 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

4 

detail below. These regions 40 of constructive interference 

allow one person 42 standing next to a first picture 44 to hear 

one soundtrack, and a second person 46 standing next to a 

second picture 48 to hear a second soundtrack. 

The apparent loudness of a sound is found by forming a 

ratio between a sound volume which is just perceptible to the 

human ear, and the Sound in question. For convenience, this 

ratio is expressed as ten times the log of the ratio of Sound 

intensity which is referred to as decibels or dB. A sound 

which has a power level often times a first sound seems to 

the human ear to be about twice as loud as the first sound. 

Thus if the sound intensity ratio is 20 dB the sound will 

sound four times as loud as the 0 dB sound. 

Sound intensity or Volume is a function of the square of 

the signal amplitude, therefore in an array containing 100 to 

1,000 speakers, the sound from all of which is made to 

constructively interfere at a region in space, the interference 

will produce by the constructive addition of the sound from 

each speaker an increase in Sound amplitude often thousand 

to one million times, theoretically achieving an increase of 

intensity at the target of 40 dB to 60 dB over the volume of 

any one speaker as heard from the same location. 

The Sound intensity at locations other than the target 

location is a function of Sound addition which is not in 

phase, but rather randomly distributed in phase and timing, 

and is proportional to the number of speakers or transducers 

in the array rather than the square of the number of speakers 

or transducers. Thus, where the Sound is not constructively 

added, the sound level will be 20 dB to 30 dB over the 

Volume of any one speaker as heard from the same location. 

The resulting difference in sound intensity levels if each 

speaker were to be operated at a sound level of 0 dB or the 

threshold of audibility would be that at everywhere in the 

listening space except the target, the out-of-phase and unin 

telligible signal would have a sound Volume of a faint 

whisper or the sound of rustling leaves while at the target a 

fully intelligible, focused and in-phase signal would have a 

Sound intensity level nearly equal to that of normal conver 

sation, to several times normal conversation level. 

Thus the perceived sound intensity, depending on the 

number of speakers, will be approximately four to eight 

times as loud in the discrete regions 40 where constructive 

interference is occurring as outside the discrete regions 40. 

The addition of some white noise which decreases audibility 

for all sounds will result in distinct noticeable and intelli 

gible sound only in discrete regions 40. 

In a natural whispering chamber Such as an ellipsoidal 

room having two foci, Sound emitted at one focus at a Sound 

level which cannot be heard a short distance away, will 

nevertheless be clearly audible at the second focus of the 

ellipsoidal room. In the whispering chamber, Sound is 

reflected to a region in space where constructive addition 

forms an audible sound. Just as a localized region of audible 

sound can be produced by the natural reflective properties of 

an ellipsoidal room, which cause every first reflection of a 

sound from the first focus to reach the second focus at the 

same time, and add together to produce a localized region of 

audible sound, a similar effect can be achieved artificially with an array of speakers. 

The audio speaker array 20 is driven to produce sound so 

that the Sound from each speaker reaches a discrete region 

40 in space at the same time. If many audio speakers were 

arranged facing inwardly on the Surface of a sphere and the 

same sound signal is then broadcast through each speaker, a 

person standing at the center of the sphere will perceive a 

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US 7,130,430 B2 

5 

signal created by the constructive interference of all the 

speakers which is louder than the mere algebraic Sum of the 

Volume of each speaker. 

If a single speaker located on the sphere surface is given 

a first sound level as heard from the center of the sphere, ten 

speakers at the same Volume without constructive interfer 

ence would normally sound twice as loud (10 dB). However, 

if the ten speakers are placed on the sphere's surface to result 

in constructive interference, a sound amplitude of ten 

squared (20 dB) will be perceived, or a sound four times as 

loud as the single speaker. Similarly, if 100 speakers are use, 

a sound amplitude of 100 squared (40 dB) will be perceived, 

a Sound 16 times as loud as a single speaker will be 

perceived. 

A flat array 20 such as shown in FIG. 1 and FIG. 2 can be 

made to simulate or have the effect of an array of speakers 

on a sphere by providing each speaker with a signal which 

is delayed in time, so that the signal from each speaker 

reaches a common focus at the same time. This means that 

speakers that are nearer the focus must have more delay than 

the speakers which are farther from the focus. If the speaker 

furthest from the common focus region 40 has no delay, the 

speaker nearest the common focus must have the delay 

which is equal to the difference in distance between the 

nearest and furthest speakers divided by the speed of sound. 

Thus the minimum amount of delay which the system must 

be capable of producing is the maximum range of distances 

between the speakers 22 and the discrete region divided by 

the speed of Sound. To avoid needing to vary the maximum 

delay provided by the sound reproduction system 36 

depending on the location within the room 26, a maximum 

delay is selected equivalent to the maximum dimension of 

the array 20. 

The delay required for each speaker can be calculated by determining the distance D, between the speaker furthest 

from the common focus 40, and setting the delay for the 

furthest speaker equal to Zero or a constant. The distance D 

for any particular speaker is determined between the par 

ticular speaker and the common focus 40, the delay in the 

Sound being emitted from a particular speaker is equal to the 

maximum distance minus the particular distance divided by 

the speed of sound V. 

(D-D), V-Delay in seconds 

As shown in FIG. 2, four representative speakers are 

arranged in a linear array. The first speaker 50 is closest to 

a target represented by the ear 52. A second speaker 54 is 

slightly more distant, a third speaker 56 more distant still, 

and a fourth speaker 58 is still more distant. An identical 

audio signal i.e. a time varying audio drive Voltage, is 

supplied to each speaker 50, 54, 56, 58, but the signal is 

delayed in time so that the audio output 60 of the fourth 

speaker 58 begins first, followed by the audio output 62 of 

the third speaker 56, then the audio output 64 of the second 

speaker 54 and lastly the audio output 66 of the first speaker 

50. The audio outputs 60, 62, 64, 66, because of the varying 

delays, each reach a sphere 68 which is centered about the 

target 52 at the same time and propagate forward reaching 

the target 52 to constructively interfere producing an 

increased volume of sound in the volume of constructive 

interference. 

A time varying audio drive Voltage with the correct delay 

for each speaker 50, 54,56, 58 is created from a single audio 

source 70, as shown in FIG. 2. The audio source, if an analog 

source, is digitally sampled by a A/D converter 72. A typical digital signal is sampled 44,000 times per second which is 

the standard for reproducing audio frequency Sound with an 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

6 

acceptable level of distortion. If the audio source is digital the existing digital samples may be stored directly in the 

memory storage register 78 of the memory stack 76. 

The maximum delay needed is proportional to the maxi 

mum difference in distance between any two speakers of of 

the array 20 and the target which is the discrete region 40. 

The speed of Sound in air at room temperature is approxi 

mately 1,000 fps. For each speaker 22, the target distance is 

the distance between that speaker and the target 40. The 

maximum delay needed is the maximum difference between 

the target distances of any two speakers 22 divided by 1,000. 

The maximum difference in the target distances of any two 

speakers must necessarily be less than the maximum dimen 

sion of the speaker array 20, which must be less than the 

maximum dimension of the room in which the speakers are 

situated. The precise amount of delay necessary will of 

course be dependent on the position of the target 40 in space 

relative to the array 20. Because the location of the target 40 

may be adjustable either in real-time, or at set intervals, the 

amount of delay may be simply taken as the maximum room 

dimension or the maximum array dimension, or by looking 

at a particular situation to determine the actual needed delay. 

A digital sample can be simply thought of as the ampli 

tude of an audio signal at a particular point in time. The 

amplitude of the audio signal is the Sum of the amplitude of 

all audio frequencies present. As will be understood by those 

skilled in the art of audio frequency sound reproduction the 

sample frequency must be sufficiently higher than the high 

est frequency which it is desired to reproduce, and various 

analog/or digital filtering must be used to reduce the effects 

of digital sampling on signal quality. 

The A/D converter 72 produces a standard digital signal comprised of a series of values corresponding to each timed 

sample of the audio signal taken each /44,000th of a second. 

The samples 74 are sent to the memory stack 76 which are 

incremented with the addition of each new sample, incre 

menting the previously stored samples to the next memory 

storage register 78. Each location in the memory stack will 

thus contain a digital word. The digital word will typically 

be a 16-bit word for standard sound quality, but could be of 

higher or lower precision. Because each additional storage 

register represents a time increment of 44,000th of a second, 

a storage register which contains a signal delayed by a 

selected amount can be determined by dividing the desired 

time delay by 44,000 to determine the address of the register which contains a signal with the selected delay. A computer 

or microprocessor 80 stores the Sound samples and incre 

ments all the samples by 44,000 times a second. The total 

number of storage registers necessary depends on the total 

time delay needed which, as discussed above, is less than the 

maximum dimension of the speaker array 20. The total 

number of storage registers necessary is a product of the 

total time delay needed and the number of samples taken per 

second. The total delay time, as discussed above, is gov 

erned by the maximum dimension of the speaker array 20. 

To provide an audio signal to each speaker, the computer 

controls a pointer 79 for each speaker which is directed to a 

particular memory register which is read out 44,000 times a 

second in Synchronization with the memory registers being 

incremented. Each speaker 22 has a related pointer 79, and 

the computer 80 contains in memory all the pointers 79 

which are collectively referred to as a pointer array. The end 

result is a digital signal with a selected delay which is which 

is converted to a time varying audio drive Voltage, and 

applied to each individual speaker of the speaker array 20. 

Referring to FIG. 1, a sound reproduction system 36 is 

shown producing a plurality of discrete sound regions 40. 

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7 

The regions are positioned in front of pictures within a 

museum gallery 26. One person 42 stands in front of a first 

picture 44. Indicia 86, such as a “STAND HERE' legend on 

the floor, indicates where the person 42 should stand to hear 

a description of the first picture 44. At the same time, a 5 

second person 46 standing in a different part of the room is 

viewing a second picture 48. The second person’s head is 

positioned within a discrete region 40 which provides an 

audio description of the second picture 48. The “STAND 

HERE' legend on the floor provides information for gaining 10 

access to the Sound target. Because people vary in height, 

two or more discreet audio regions 40 may be formed at 

different heights above the ground into which is broadcast 

the same audio track. Arrows 92 indicate sound which is 

being transmitted to constructively interfere to form the 15 

discrete regions 40. Although the Sound is coming from all 

the speakers, or a Substantial majority of the speakers, particularly those located in the vicinity of a particular 

discrete region 40, for clarity only a few arrows are shown. 

To produce several Sound regions 40 from a single array 20 

of speakers, a plurality of audio sources 94 are digitized by 

a plurality of A/D digital samplers 95, and storage in 

memory stacks 96 which are used to contained a multiplicity 

of sound samples 97 sequentially store from each audio 

Source 94, to form an audio Source signal. For a particular 25 

speaker 98, sound from each audio source signal will be 

delayed by a different amount so that the sound transmitted 

by each speaker 22 in the array 20 can contribute to the 

constructive interference of Sound at a plurality of locations 

to create a plurality of Sound regions each with their own 30 

soundtrack. Each particular speaker 98 is associated with a 

pointer 100 corresponding to each memory location which 

will produce a signal delay which will cause a particular 

signal to constructively interfere at a particular discrete 

region 40. Several Such audio signals, with their character- 35 

istic delay may be increased or decreased in amplitude, by 

a volume control 108, which may be assembled digital multiplier. The amplitude adjusted audio signals are added 

with a digital adder 102 and converted to an analog signal with a digital-to-analog converter 104, then amplified by the 40 

amplifier 106. The signal associated with each particular set 

of pointers 100 is then sent to a particular speaker 98. 

For the proper functioning of the sound reproduction 

system 36, each speaker must be connected to the output of 

the memory location which contains Sound data with the 45 

proper delay value. If the discrete region in which it is 

desired to produce Sound is at a fixed location, the fixed 

location with respect to the speaker array 20 can be used to 

Solve for the necessary delay and thus each speaker can be 

connected to the memory location which produces Sound 50 

with the proper delay. The set of data which is the proper 

delay for each speaker is a pointer matrix, and the value of 

the pointer matrix can be arrived at by calculation or 

empirically. If the focus of the array is progressively swept 

through the entire room, a microphone placed at the desired 55 

location 40 can readily detect when the progress of sweep 

has reached the desired location. Values contained in the 

pointer matrix when a test tone reaches a maximum Volume 

at the test location can be saved and thereafter used to 

control each speaker time delay. 60 

If it is desired to follow a person moving about a room 

with the discrete region 40 of increased sound volume, a 

tracking system may be employed to locate a wireless 

microphone placed on the person, preferably near the per 

son’s ear. The tracking system creates an interrogating target 65 

focus. The interrogating target focus is a Sub-audible tone 

pattern that is localized in three-dimensional space and 

8 

continuously scanned through the listening room. The Lis 

teners wears the wireless microphone and the listener's 

location within the listening room is fixed in relation to the 

speaker array by sensing the time at which the signal from 

a given microphone reaches its maximum. Thus the pointer 

array is constantly updated with listener's current location. 

It should be noted that this method reduces the compu 

tational load of the CPU since it eliminates the need to 

calculate the delays to be programmed into the the pointer 

matrix as the target locations are identified empirically as the 

interrogating tone is scanned through the room. The process 

of scanning a tone target is a simple matter of incrementing 

in a predetermined fashion the data elements of the the 

pointer matrix for the target focus to be scanned through the OO. 

An experiment was performed to test the Sound system of 

the invention by fabricating a 9x9 array of speakers 10 

inches on center. The eighty-one speaker emitter panel was 

constructed using one-quarter-inch thick pegboard. Low 

power, three-inch round speakers rated for 2 watts max were 

affixed to a mounting screw that extended from the back of 

each speaker co-located with the central axis of the cone of 

that speaker. The speakers were placed on a 10" grid pattern 

and affixed to the peg board. A short length of PVC tubing 

was placed around the mounting screws so that the tubing 

would expand to fill the peg board hole as the screws was 

tightened. This arrangement served to acoustically isolate 

each speaker from one another as well as centered each 

speaker so that the axis of the cone of each speaker is normal 

to the plane of the emitter panel. 

The speakers were wired to an 81 channel amplifier/phase delay apparatus. The apparatus use for producing individual 

delays for each of the 81 channels was composed of six 

digitally addressed multi-channel digital-to-analog con 

verter printed circuit boards (D to A cards) and one digital signal processing printed circuit board (DSP card) that is 

capable of addressing each channel on each D to A card. The 

D to A cards and the DSP card were interconnected and 

powered via an ISA passive backplane of an IBM PC clone. 

The D to A cards as well as the DSP card were designed and 

laid out on an AT-ISA form factor to fit the passive back 

plane. 

Each D to A card contained 16 channels of digital-to analog converter circuitry. An 8 bit data byte was written to 

each individual channel. Individual channels were addressed 

by first enabling the entire board with a board enable signal 

that is generated by the DSP card. While a given card was 

enabled, a 4 bit digital address is driven on to the passive backplane bus. A unique address was generated by the 4 bits 

for each of the 16 channels on the D to A card. Latching the 

8 bit data into an addressed channel was accomplished by driving the memory write signal to a logic low. The memory 

write signal was generated by the DSP card. Each channel of 

the D to A card was composed of an 8 bit data latch IC 

(74HC573); an 8 bit digital to analog converter IC (DAC08) 

that output a current that was proportional to a digital input 

value; and an operational amplifier configured to function as 

an analog current to Voltage converter (LM741) sent its 

output voltage to an audio power amplifier (LM380). The 

audio power amplifier drove an individual speaker for that 

channel. 

In addition to the circuits comprising the digital to analog 

converters, the D to A card also held the data bus receiver 

circuitry (74HC244), channel decoding circuitry 2 ea 

(74HC308) and logic NOR gates to combine the “memory 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 9 of 14 PageID #: 269
US 7,130,430 B2 

write” signal with the channel select signal (output of the 

74HC308) into a data latch enable signal used by the 

74HC573. 

The DSP card was comprised of Texas Instruments 32040 

CODEC and a Texas Instruments 320C50 DSP. The CODEC 

contains the audio analog-to-digital converter that outputs 

14 bit digital samples to the DSP to process. The operation 

of the system described to this point was synchronized to the 

sample rate of the CODEC. 

The DSP performed the channel delay process by means 

of a first in, first out delay line. The amount of delay for any 

given channel was preprogrammed to produce the focus at 

the predetermined location in 3 dimensional space in front of 

the emitter panel. Each time the CODEC delivers a new 

sample to the DSP, it first updates the delay line, then it 

selects a sample for each digital-to-analog converter channel 

in the 81 channel array. The input latch to each channel was 

mapped into the memory map of the DSP All 81 channels 

are written to, each with its own selected sample before the 

next new sample was delivered by the CODEC. The sample 

selected was determined from a delay pointer matrix that 

was a matrix of memory pointers that was preprogrammed 

into the DSP code at compile time. Each memory pointer in 

the matrix points to a specific address within the delay line. 

Each location in the delay line represents a specific amount 

of time delay that was equal to the amount of delay between 

samples multiplied by the number of memory locations the 

specific address was from the first location in the delay line. 

Thus the first location was the most recent sample. The 

length of the delay line used was 128 samples long. The 

apparatus allowed individual control of the delay of the 

audio signal to each speaker. 

As discussed previously, eighty-one speakers should pro 

duce a sound intensity of approximately 19 dB above the 

Volume of a single speaker, and when combined with time 

delays in accordance with the invention so that constructive 

interference is achieved for a selected region in space, a 

sound level of 38 dB above that produced by a single 

speaker should result, so that Sound in a selected region 

should be 19 dB above the ambient sound levels. The data 

set produced below consists of Sound level readings taken 

with a handheld meter which provided dB readings. The 

meter scale began at 40 dB, and meter readings were taken 

at 10 inch intervals on axis with the speakers. The sound 

delays were selected to produce a maximum volume at a 

region which was 60 inches in front of the speaker array and 

centered over the speaker which was in the fourth row from 

the top and sixth column from the left side. This reading, as 

indicated in the data set, was 59 dB. The ratings immediately 

Surrounding the target point are 43, 42, 43, 43, 43, 42, 42, 43. 

and immediately in front of the target point 48, and imme 

diately behind 46. And thus it is seen that the test apparatus 

produced a sound level which was approximately 16 dB 

above Sound levels immediately adjacent to the target point, 

and generally at least 10 dB, above any other data point with 

the exception of a data point taken ten inches above a noisy 

speaker in this seventh row, six from the left, which was the 

result of a faulty amplifier driving a particular speaker. 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

10 inches 

20 inches 

30 inches 

40 inches 

50 inches 

4 

4 

4 

43 

43 

43 

43 

43 

43 

43 

43 

42 

42 

41 

42 

42 

43 

42 

42 

43 

43 

444 4 

4 

444 4 

4 

4444 4 

1. O 

5 

4 444 4 

4 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 10 of 14 PageID #: 270
US 7,130,430 B2 

11 

-continued 

40 42 43 43 42 42 42 40 43 

43 42 42 42 42 42 42 42 42 

43 43 43 43 43 42 43 43 42 

43 45 49 43 43 59 43 42 43 

60 inches 42 42 42 42 42 42 43 42 41 

42 42 42 42 43 42 43 42 42 

40 40 43 42 43 48 42 40 43 

42 43 43 42 42 45 42 42 42 

42 40 43 42 43 43 42 40 42 

70 inches 4 4 4 4 4 4 4 4 4 

80 inches 4 4 4 4 4 4 4 4 4 

90 inches 4 4 4 4 4 4 4 4 4 

40 

42 

43 

40 

100 inches 42 

40 

42 

42 

42 

40 

42 

42 

41 

42 

40 

42 

42 

43 

40 

42 

43 

42 

42 

41 

42 

42 

42 

40 

42 

42 

42 

42 

40 

42 

42 

42 

40 

42 

42 

40 

41 

41 

42 

42 

42 

40 

42 

42 

42 

42 

42 

43 

43 

43 

40 

42 

42 

42 

41 

41 

43 

42 

43 

40 

42 

42 

41 

42 

40 

42 41 

43 42 

42 42 

40 

42 

41 

41 

41 

40 

It should be understood that the amplitude of each speaker maybe adjusted to improve the sound volume in a particular discrete region 40. Alternatively, speaker Volume may be 

adjusted to reduce Volume in a particular region where 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

12 

Sound is unintentionally audible above background noise 

levels. Such regions might arise due to room acoustics, or 

speaker array geometry. Heuristic computer algorithms 

working with microphones placed between speakers in the 

array, or with microphones moved about a room could use 

fuZZy logic systems, or other systems of systematic or 

random variations to achieve a maximum volume of Sound 

at discreet locations while simultaneously minimizing Sound 

present outside of the discrete locations. By adjusting the 

variables of delay and Volume of each speaker, a heuristic 

approach can be taken to find solutions which are better than 

those based on assumptions about room and speaker acous 

tics. Even moderately sized rooms can allow a new Sound 

response to be established many times a second allowing 

thousands of iterations to be performed in a few minutes. 

These iterations may simultaneously be performed at mul 

tiple frequencies. 

It should be understood that when, a means for applying 

a time varying audio drive Voltage, i.e. the signal used to 

drive individual speakers is described as substantially iden 

tical, the signals are defined as being Substantially identical, 

although they vary in amplitude. The term, Substantially 

identical, means capable of constructive interference when 

used in the sound system 36 of this invention. 

It should be understood that D class amplifiers which 

utilize pulse width modulation to drive audio speakers directly from line voltage could be used to drive the speakers 

22 of the sound reproduction system 36. This approach 

eliminates the need for audio amplifiers and has greatly increased efficiency in converting electrical power into 

audio output. D class amplifiers thus require only a power 

Source and the digital input to drive the speakers. As shown 

in FIG. 4, a ceiling tile 28 containing a multiplicity of 

speakers can be arranged to receive power and digital 

information addressed to each speaker. It is likely that a 

single integrated chip could contain all the components 

necessary to receive the digital output over a network, Such 

as ethernet, and to drive the speakers. Because of a very low 

power, in Some applications, thousandths to perhaps hun 

dredths of a Watt output for each speaker in the array, it is 

possible that the audio speaker could be fabricated on the 

same chip as the network connection and D class amplifier. 

It should be understood that stereo sound without head 

phones could be produced by creating discrete regions in 

space 40 which are closely spaced and contained the left and 

right channels making up the stereo signal, so that when 

properly positioned, a person could hear stereo Sound. Noise 

cancellation with the sound system 36 is also possible, particularly where the noise to be canceled can be predicted, 

either by monitoring the noise at its source, or because the 

noises is of periodic nature. 

In should be understood that the speakers 22 are prefer 

ably mounted on the ceiling in part because this will 

minimize interference of objects and persons with the Sound 

transmitted from the speakers to create the discrete regions in space 40. However the sound system 36 is inherently resistant to being blocked by objects and persons especially 

when the array 20 is spread over a wide area, so that sound 

reaches the discrete regions in space over a wide angle of 

convergence. 

It should be understood that the sound system of this 

invention can provide distinct and controllable volume lev 

els for different individuals in the same listening room. It 

should also be understood that the sound system of this 

invention can be used to create multilingual School rooms or 

auditoriums where listeners if properly equipped with a 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 11 of 14 PageID #: 271
US 7,130,430 B2 

14 

at least a second audio source which is offset in time by an amount which is related to the distance between 

each speaker and the second defined sound target 

wherein a sum of the first audio source which is offset 

in time and the second audio source which is offset in 

time is used to produce the time varying audio drive 

Voltage so that Substantially identical Sound from the 

first audio source signal reaches the first Sound target at 

the same time, and Substantially identical sound from 

the second audio source signal reaches the second 

target at the same time. 

3. A speaker system for producing localized regions of 

Sound comprising: 

13 

locating device or seated in the proper location can hear a 

presenter in his or her own language without the use of 

cumbersome headphones. 

A sound system of this invention may also make possible 

having both edited and non-edited versions of motion pic- 5 

ture film dialog presented to the same audience at the same 

time, or even different plot lines could be presented to 

different portions of the audience. Hands-free phone opera 

tion might be achieved in open office environments while 

still maintaining private conversation. Buildings so 

equipped could take advantage of listener tracking to auto 

matically route telephone and intercom signals to the desired 

recipient without the need of a handset, or a public address 

10 

system which is heard by all. 

amount which is related to the distance between each 

speaker and the first defined Sound target; and 

a multiplicity of audio frequency speakers; 

It should further be understood that the Sound produced 15 at least one defined sound target spaced from each of the 

by the sound system of this invention is a real image which speakers of the multiplicity of speakers, wherein each 

actually comes from the location it appears to come from, speaker has a means for applying a time varying audio 

creating many opportunities for Sound reproduction and drive Voltage which is Substantially identical, except 

special effects of video games, Multimedia presentations that each audio drive voltage is offset in time by an 

and high fidelity music. 2O amount which is related to the distance between each 

It is understood that the invention is not limited to the speaker and the defined Sound target, so that Substan 

particular construction and arrangement of parts herein tially identical sound from each speaker reaches the 

illustrated and described, but embraces such modified forms Sound target at the same time; and 

th as come within the scope of the following claims. wherein the means for applying a time varying audio 

Ca1. 25 drive voltage includes a class D amplifier. 

A.E." for producing localized regions of 4. A speaker system for producing localized regions of 

a multiplicity of audio frequency speakers; sy compr1S1ng: dio f d k d 

at least one defined sound target spaced from each of the at least 100 audio Irequency sound speakers arrange speakers of the multiplicity of speakers, wherein each 30 spaced apart in an array, in a space filled with air; 

speaker has a means for applying a time varying audio a first sound target spaced from the array; 

drive voltage which is substantially identical, except a second Sound target spaced from the array; 

that each audio drive voltage is offset in time by an a means for determining the distance between each 

amount which is related to the distance between each speaker and the first Sound target; 

speaker and the defined sound target, so that substan- 35 a means for determining the distance between each 

tially identical Sound from each speaker reaches the speaker and the second Sound target; 

Sound target at the same time; a first audio Source; 

wherein the speakers are arranged in a single plane; a second audio source: 

further comprising a room having a ceiling, and wherein a means for delaying in time transmission of the first 

the speakers are mounted to the ceiling; and wherein 40 audio Source to each one of the speakers by an amount 

R the splits audio St. R of time which is related to the distance between each 

ormed as part of a ceiling panel which can be joine one of the speakers and the first Sound target; 

to a further ceiling and panel, to communicate power a means for delaying in time transmission of the second 

St. data between said ceiling panel and said further audio Source to each one of the speakers by an amount 

ce111ng panel. 45 of time which is related to the distance between each 

2. A speaker system for producing localized regions of one of the speakers and the second sound target; and 

Sound comprising: a means for adding together the first audio signal and the 

a multiplicity of audio frequency speakers; second audio signal to create a combined signal, and 

at least one defined sound target spaced from each of the Supplying said combined signal to each sound speaker 

speakers of the multiplicity of speakers, wherein each 50 so that sound produced by each of the at least 100 

speaker has a means for applying a time varying audio speakers generates a first localized region of Sound at 

drive Voltage which 1S substantially identical, except the first Sound target and a second localized region of 

that each audio drive Voltage is offset in time by an Sound at the second Sound target. amount which is related to the distance between each 5. The speaker system of claim 4 wherein the speakers are speaker and the defined sound target, so that Substan- 55 tially identical Sound from each speaker reaches the arranged in a single plane. Sound target at the same time; 6. The speaker system of claim 4 further comprising a 

at least a first defined Sound target and a second defined OO having a ceiling wherein the speakers are mounted to 

Sound target, the second sound target being spaced the ceiling. from the first sound target, and the first sound target and 60 7. The Speaker System of claim 5 wherein each of the 

the second sound target being spaced from each of the multiplicity of audio frequency speakers is formed as part of 

speakers of the multiplicity of speakers, and wherein a ceiling panel which can be joined together to communicate 

the means for applying a time varying audio drive power and data. 

Voltage comprises: 8. The speaker system of claim 4 further comprising: 

at least a first audio source which is offset in time by an 65 a room; and 

indicia positioned within the room providing information 

for gaining access to the Sound target. 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 12 of 14 PageID #: 272
US 7,130,430 B2 

15 

9. The speaker system of claim 4 wherein the means for 

adding together the first audio signal and the second audio 

signal includes a class D amplifier driving each speaker. 

10. A method of producing a region of localized sound 

intensity in air which is spaced from a source of sound 

generation, comprising the steps of: 

Selecting a region in space for creating a region of 

localized sound having a first sound amplitude; positioning a multiplicity of spaced apart audio frequency 

Sound sources spaced from the region in space, each 

audio frequency sound source defining a distance 

between each sound source and the selected region in 

Space; 

emitting from each sound source a sound having a second 

sound amplitude which is at least 20 dB less than the 

first sound amplitude: creating the region of localized sound having the first 

Sound amplitude by emitting from each sound source a 

Substantially identical sound wave, wherein each sub 

stantially identical sound wave is delayed in time as 

emitted by each sound source of the multiplicity of 

Sound sources by an amount of time which is related in 

Such a way to the defined distance between each sound 

Source and the region in space, so that the substantially identical sound waves constructively interfere to pro duce the region of localized sound having the first 

sound amplitude. 

11. The method of claim 10 wherein the sound sources are 

arranged in a single plane. 

12. The method of claim 10 wherein the sound sources are 

formed as part of ceiling panels which are joined together to 

communicate power and data. 

13. The method of claim 10 further comprising a step of 

directing a listener to the region of localized sound. 

14. The method of claim 10 wherein the step of creating the sound wave of the first sound amplitude includes the step of sending a digitized waveform through a class D amplifier 

to each sound source. 

15. The method of claim 10 further comprising: Selecting a second region in space for creating a second 

region of localized sound having a third amplitude, wherein each of the audio frequency sound sources 

defines a second distance between each sound source 

and the selected second region in space; emitting from each sound source a second substantially identical sound wave at a fourth sound amplitude which 

is at least 20 dB less than the third amplitude; creating the sound wave of the third amplitude by the 

emitting from each sound source the second substan 

tially identical sound wave, wherein the second sub 

stantially identical sound wave is delayed in time as 

emitted by each sound source of the multiplicity of 

Sound sources by an amount of time which is related in 

Such a way to the defined second distance between each 

Sound source and the second region in space, so that the 

Second substantially identical sound waves construc 

tively interfere to produce the second region of local 

ized sound having the third amplitude. 16. A speaker system for producing at least one localized 

region of Sound, comprising: 

5 

10 

15 

25 

30 

35 

40 

45 

50 

55 

16 

a first audio source: 

a central processing unit; 

an array of speakers in fixed relation to one another; 

a first stack of data registers maintained by the central 

processing unit, wherein samples of the first audio 

Source are taken at selected intervals, and are stored in 

the first stack of data registers, the location of each 

sample being incremented sequentially through the first 

stack of data registers as each subsequent sample is 

taken; and 

a first pointer array maintained by the central processing unit, the first pointer array having a pointer correspond ing to each of the speakers in the array, and pointing to 

one of the first stack of data registers corresponding to 

the time delay necessary to cause the sound emitted by each speaker to reach a first localized region of sound 

Substantially simultaneously, the central processing unit simultaneously reading the changing contents of a 

data register associated with a particular pointer to a 

particular speaker, wherein the volume of the sound 

produced by each speaker in the array is at least 20 dB 

below the sound volume of the sound emitted at the first 

localized region of sound. 

17. The speaker system of claim 16 further comprising: 

a second audio source: 

a second stack of data registers maintained by the central 

processing unit, wherein samples of the second audio 

Source are taken at the selected intervals and are stored 

in the second stack of data registers, the location of 

each sample being incremented sequentially through 

the second stack of data registers as each subsequent 

sample of the second audio source is taken; and 

a second pointer array maintained by the central process ing unit, the second pointer array having a pointer corresponding to each of the speakers in the array, and 

pointing to one of the second stack of data registers corresponding to the time delay necessary to cause the 

Sound emitted by each speaker to reach a second 

localized region of sound substantially simultaneously, wherein the samples of each first stack register and 

second stack register corresponding to a particular speaker are added and supplied to the particular speaker 

to produce both the first localized region of sound and 

a second localized region of sound spaced from the first 

localized region of sound. 

18. The speaker system of claim 16 further comprising a 

microphone mounted to a listener, the microphone in wire 

less communication with the central processing unit, such 

that the central processing unit may direct an interrogating frequency throughout a volume to determine the location of 

the microphone and thereby determine the desired position 

of the first localized region of sound. 

19. The speaker system of claim 17 wherein the first audio 

Source includes speech in a first language, and the second 

audio source includes speech in a second, different, lan 

gllage. 

ck ck ck k ck 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 13 of 14 PageID #: 273
UNITED STATES PATENT AND TRADEMARK OFFICE 

CERTIFICATE OF CORRECTION 

PATENT NO. : 7,130,430 B2 Page 1 of 1 

APPLICATIONNO. : 10/024159 

DATED : October 31, 2006 

INVENTOR(S) : Jeffrey P. Milsap 

It is certified that error appears in the above-identified patent and that said Letters Patent is 

hereby corrected as shown below: 

In column 14, line 49, after “each and before “speaker delete “sound 

Signed and Sealed this 

Sixth Day of February, 2007 

WDJ 

JON. W. DUDAS 

Director of the United States Patent and Trademark Office 

Case 2:23-cv-00199-JRG Document 9-1 Filed 06/21/23 Page 14 of 14 PageID #: 274