audio spotlighting full report

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ABSTRACT
Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Joseph Pompei s Holosonic Research Labs invented the Audio Spotlight that is made of a sound processor, an amplifier and the transducer. The American Technology Corporation developed the HyperSonic Sound-based Directed Audio Sound
System. Both use ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.
The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc.
Thus audio spotlighting helps us to control where sound comes from and where it goes!
INDEX
1.0 INTRODUCTION 3
2.0 THEORY 6
2.1 TECHNOLOGY OVERVIEW 10

2.2 COMPONENTS AND SPECIFICATIONS 11
2.2.1 SOUND BEAM PROCESSOR/AMPLIFIER 11
2.2.2 AUDIO SPOTLIGHT TRANSDUCER 12
2.3 NON-LINEARITY OF AIR 13
2.4 DIRECT AUDIO AND PROJECTED AUDIO 20
3.0 SPECIAL FEATURES 24

4.0 APPLICATIONS/ FUTURE EXPANSIONS 25

5.0 CONCLUSION 28
6.0REFERENCE 29
1.0 INTRODUCTION
JUST WHAT IS AUDIO SPOTLIGHTING
Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it,ie to focus sound into a coherent and highly directional beam . It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker.
The Audio Spotlight & Hyper Sonic Sound Technology (developed by American Technology Corporation), uses ultrasonic energy to create extremely narrow beams of sound that behave like beams of light. Audio spotlighting exploits the property of non-linearity of air. When inaudible ultrasound pulses are fired into the air, it spontaneously converts the inaudible ultrasound into audible sound tones, hence proved that as with water, sound propagation in air is just as non-linear, and can be calculated mathematically. A device known as a parametric array employs the non-linearity of the air to create audible by-products from inaudible ultrasound, resulting in an extremely directive, beamlike wide-band acoustical source. This source can be projected about an area much like a spotlight, and creates an actual spatialized sound distant from the transducer. The ultrasound column acts as an airborne speaker, and as the beam moves through the air, gradual distortion takes place in a predictable way. This gives rise to audible components that can be accurately predicted and precisely controlled.
2.0 THEORY
IN TO THE DEPTHS OF AUDIO SPOTLIGHTING TECHNOLOGY
What ordinary audible sound & Conventional Loud Speakers lack
What we need
About a half-dozen commonly used speaker types are in general use today. They range from piezoelectric tweeters that recreate the high end of the audio spectrum, to various kinds of mid-range speakers and woofers that produce the lower frequencies. Even the most sophisticated hi-fi speakers have a difficult time in reproducing clean bass, and generally rely on a large woofer/enclosure combination to assist in the task. Whether they be dynamic, electrostatic, or some other transducer-based design, all loudspeakers today have one thing in common: they are direct radiating-- that is, they are fundamentally a piston-like device designed to directly pump air molecules into motion to create the audible sound waves we hear. The audible portions of sound tend to spread out in all directions from the point of origin. They do not travel as narrow beams which is why you don t need to be right in front of a radio to hear music. In fact, the beam
angle of audible sound is very wide, just about 360 degrees. This effectively means the sound that you hear will be propagated through air equally in all directions.
In order to focus sound into a narrow beam, you need to maintain a
low beam angle that is dictated by wavelength. The smaller the wavelength, the less the beam angle, and hence, the more focused the sound. Unfortunately, most of the human-audible sound is a mixture of signals with varying wavelengths between 2 cms to 17 metres (the human hearing ranges from a frequency of 20 Hz to 20,000 Hz). Hence, except for very low wavelengths, just about the entire audible spectrum tends to spread out at 360 degrees. To create a narrow sound beam, the aperture size of the source also matters a large loudspeaker will focus sound over a smaller area. If the source loudspeaker can be made several times bigger than the wavelength of the sound transmitted, then a finely focused beam can be created. The problem here is that this is not a very practical solution. To ensure that the shortest audible wavelengths are focused into a beam, a loudspeaker about 10 metres across is required, and to guarantee that all the audible wavelengths are focused, even bigger loudspeakers are needed.
Here comes the acoustical device AUDIO SPOTLIGHT invented by Holosonics Labs founder Dr. F. Joseph Pompei (while a graduate student at MIT), who is the master brain behind the development of this technology.
FIG.1:-AUDIO SPOTLIGHT CREATES FOCUSED BEAM OF SOUND UNLIKE CONVENTIONAL LOUD SPEAKERS
Audio spotlight looks like a disc-shaped loudspeaker, trailing a wire, with a small laser guide-beam mounted in the middle. When one points the flat side of the disc in your direction, you hear whatever sound he's chosen to play for you perhaps jazz from a CD. But when he turns the disc away, the sound fades almost to nothing. It's markedly different from a conventional speaker, whose orientation makes much less difference.
Fig 2:- F.JOSEPH POMPIE AT THE MEDIA LAB OF THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY DEMONSTRATES HOW INVISIBLE ULTRASOUND WAVES, AS ILLUSTRATED HERE, COULD HELP STEER SOUND.
2.1 TECHNOLOGY OVERVIEW
The Audio Spotlight & Hyper Sonic Sound Technology (developed by American Technology Corporation), uses ultrasonic energy to create extremely narrow beams of sound that behave like beams of light. Ultrasonic sound is that sound that has very small wavelength in the millimeter range and you can t hear ultrasound since it lies beyond the threshold of human
2.2 COMPONENTS AND SPECIFICATIONS
Audio Spotlight consists of three major components: a thin, circular transducer array, a signal processor and an amplifier. The lightweight, nonmagnetic transducer is about .5 inches (1.27 centimeters) thick, and it typically has an active area 1 foot (30.48 cm) in diameter. It can project a three-degree wide beam of sound that is audible even at distances over 100 meters (328 feet). The signal processor and amplifier are integrated into a system about the size of a traditional audio amplifier, and they use about the same amount of power.
2.2.1 SOUND BEAM PROCESSOR/AMPLIFIER
Worldwide power input standard
Standard chassis 6.76/171mm (w) x 2.26/57mm (h)x 11/280mm (d), optional rack mount kit
Audio input: balanced XLR, 1/4 and RCA (with BTW adapter) Custom configurations available eg. Multichannel
2.2.2 AUDIO SPOTLIGHT TRANSDUCER
17.5/445mm diameter, 1/2/12.7mm thick, 4lbs/1.82kg
Wall, overhead or flush mounting
Black cloth cover standard, other colours available
Audio output: 100dB max
1% THD typical @ 1kHz
Usable range: 20m
Audibility to 200m
Optional integrated laser aimer 13/ 330.2mm and 24/ 609.6mm diameter also available
Fully CE compliant
Fully realtime sound reproduction - no processing lag
Compatible with standard loudspeaker mounting accessories Due to continued development, specifications are subject to change.
2.3 NON-LINEARITY OF AIR
Audio spotlighting exploits the property of non-linearity of air. When inaudible ultrasound pulses are fired into the air, it spontaneously converts the inaudible ultrasound into audible sound tones, hence proved that as with water, sound propagation in air is just as non-linear, and can be calculated mathematically. A device known as a parametric array employs the non-linearity of the air to create audible by-products from inaudible ultrasound, resulting in an extremely directive, beamlike wide-band acoustical source. This source can be projected about an area much like a spotlight, and creates an actual spatialized sound distant from the transducer. The ultrasound column acts as an airborne speaker, and as the beam moves through the air, gradual distortion takes place in a predictable way. This gives rise to audible components that can be accurately predicted and precisely controlled. However, the problem with firing off ultrasound pulses, and having them interfere to produce audible tones is that the audible components created are nowhere similar to the complex signals in speech and music. Human speech, as well as music, contains multiple varying frequency signals, which interfere to produce sound and distortion. To generate such sound out of pure ultrasound tones is not easy. This is when teams of researchers from Ricoh and other Japanese companies got together to come up with the idea of using pure ultrasound signals as a carrier wave, and superimposing audible speech and music signals on it to create a hybrid wave. If the range of human hearing is expressed as a percentage of shift from the lowest audible frequency to the highest, it spans a range of 100,000%. No single loudspeaker element can operate efficiently or uniformly over this range of frequencies. In order to deal with this speaker manufacturers carve the audio spectrum into smaller sections. This requires multiple transducers and crossovers to create a 'higher fidelity' system with current technology.
FIG.3:-PARAMETRIC LOUDSPEAKER- AMAZING AUDIO SPOTLIGHT
(Airborne ultrasounds of 28kHz are envelope-modulated with audio signals. Inherent non-linearity of the air works as a de-modulator. Thus de-modulated sounds impinge on our eardrums. We can hear those sounds! )
Using a technique of multiplying audible frequencies upwards and superimposing them on a "carrier" of say, 200,000 cycles the required frequency shift for a transducer would be only 10%. Building a transducer that only needs to produce waves uniformly over only a 10% frequency range.
FIG.4:-SHOWING THE DIFFERENCE IN MODULATING AUDIBLE
FREQUENCIES WITH ULTRASONIC CARRIER
This is similar to the idea of amplitude modulation (AM), a technique used to broadcast commercial radio stations signals over a wide area. The speech and music signals are mixed with the pure ultrasound carrier wave, and the resultant hybrid wave is then broadcast. As this wave moves through the air, it creates complex distortions that give rise to two new frequency sets, one slightly higher and one slightly lower than the hybrid wave. Berktay s equation holds strong here, and these two sidebands interfere with the hybrid wave and produce two signal components, as the equation says. One is identical to the original sound
wave, and the other is a badly distorted component. This is where the problem lies the volume of the original sound wave is proportional to that of the ultrasounds, while the volume of the signal s distorted component is exponential. So, a slight increase in the volume drowns out the original sound wave as the distorted signal becomes predominant. It was at this point that all research on ultrasound as a carrier wave for an audio spotlight got bogged down in the 1980s.
Focusing on the signal s distorted component, since the signal component s behavior is mathematically predictable, the technique to create the audio beam is simple; modulate the amplitude to get the hybrid wave, then calculate what the Becktay s Equation does to this signal, and do the exact opposite. In other words, distort it, before Mother Nature does it.
Finally, pass this wave through air, and what you get is the original sound wave component whose volume, this time, is exponentially related to the volume of the ultrasound beam, and a distorted component, whose volume now varies directly as the ultrasound wave.
By creating a complex ultrasound waveform (using a parametric array of ultrasound sources), many different sources of sound can be created. If their phases are carefully controlled, then these interfere destructively laterally and constructively in the forward direction, resulting in a collimated sound beam or audio spotlight. Today, the transducers required to produce these beams are just half an inch thick and lightweight, and the system required to drive it has similar power requirements to conventional amplifier technology.
FIG.5:-COMPUTER SIMULATION OF SOUND PROPAGATION: COMPLEX SET OF HIGH-INTENSITY ULTRASOUND SIGNAINTERMODULATEAIR. AMONG THE PRODUCTS IS A COLLIMATED AUDIO "SPOTLIGHT".
2.4 DIRECT AUDIO AND PROJECTED AUDIO
There are two ways to use Audio Spotlight. First, it can direct sound at a specific target, creating a contained area of listening space which is called Direct Audio. Second, it can bounce off of a second object, creating an audio image. This audio image gives the illusion of a loudspeaker, which the listener perceives as the source of sound, which is called projected Audio. This is similar to the way light bounces off of objects. In either case, the sound s source is not the physical device you see, but the invisible ultrasound beam that generates it
FIG.6:- DIRECT AUDIO AND PROJECTED AUDIO
Hyper Sonic Sound technology provides linear frequency response with virtually none of the forms of distortion associated with conventional speakers.
Physical size no longer defines fidelity. The faithful reproduction of sound is freed from bulky enclosures. There are no, woofers, tweeters, crossovers, or bulky enclosures. Thus it helps to visualize the traditional loudspeaker as a light bulb, and HSS technology as a spotlight, that is you can direct the ultrasonic emitter toward a hard surface, a wall for instance, and the listener perceives the sound as coming from the spot on the wall. The listener does not perceive the sound as emanating from the face of the transducer, only from the reflection off the wall.
Contouring the face of the HSS ultrasonic emitter can tightly control Dispersion of the audio wave front. For example, a very narrow wave front might be developed for use on the two sides of a computer screen while a home theater system might require a broader wave front to envelop multiple listeners.
FIG.7:-CONVENTIONAL LOUDSPEAKER & ULTRASONIC EMITTER
3.0 SPECIAL FEATURES OF AUDIO SPOTLIGHT
A COMPARISON WITH CONVENTIONAL LOUD SPEAKER:-
Creates highly FOCUSED BEAM of sound
Sharper directivity than conventional loud speakers using Self demodulation of finite amplitude ultrasound with very small wavelength as the carrier
Uses inherent non-linearity of air for demodulation
Components- A thin circular transducer array, a signal processor & an amplifier.
Two ways to use- Direct & projected audio
Wide range of applications
Highly cost effective
4.0 APPLICATIONS OF AUDIO SPOTLIGHTING -TOWARDS THE FUTURE
"So you can control where your sound comes from and where it goes," says Joe Pompei, the inventor of Audio Spotlight. , Pompei was awarded a Top Young Innovator award from Technology Review Magazine for his achievements.
The targeted or directed audio technology is going to tap a huge commercial market in entertainment and in consumer electronics, and the technology developers are scrambling to tap into that market. Analysts claim that this is possibly the most dramatic change in the way we perceive sound since the invention of the coil loudspeaker. The technology that the Holosonics Research Labs and the American Technology Corporation are lining up may seem to be a novelty of sorts, but a wide range of applications are being targeted at it.
Continuing to improve on the commercial success of the Audio Spotlight sound system, Holosonics has announced that its next-generation laser-like sound system, with improved performance and lower cost, is now actively in production. These new systems are being exhibited at the 2004 Consumer Electronics Show in Las Vegas alongside MIT Media Lab technology.
The performance and reliability of the Audio Spotlight have made it the choice of the Smithsonian Institution, Motorola, Kraft, and Cisco Systems etc.
Holosonics put in four individual Audio Spotlights into the Daimler Chrysler MAXXcab prototype truck to let all the passengers enjoy their own choice of music. Boston Museum of Science - as well as the United States military.There is an even bigger market for personalized sound systems in entertainment and consumer electronics.
Holosonic Labs is working on another interesting application at the Boston Museum of Science that allows the intended listeners to understand and hear explanations, without raising the ambient sound levels. The idea is that museum exhibits can be discretely wired up with tiny speaker domes that can unobtrusively, provide explanations
. There are also other interesting applications that they are looking at, such as private messaging using this system without headphones special effects at presentations as well as special sound theme parks that could put up animated sound displays similar to today s light shows. Holosonic has installed their Audio Spotlight system at Tokyo s Sega Joyopolis theme park.

The US Navy has installed sound beaming technology on the deck of an Aegis-class Navy destroyer, and is looking at this as a substitute to the radio operator s headphones.
5.0 CONCLUSION
Being the most radical technological development in acoustics since the coil loudspeaker was invented in 1925.. The audio spotlight will force people to rethink their relationship with sound
-NewyorkTimes
So we can conclude- Audio Spotlighting really put sound where you want it and will be A REAL BOON TO THE FUTURE.
6.0 REFERENCES
thinkdigit.com
holosonics.com
spie.org
howstuffworks.com
abcNEWS.com
ENGINEERING PHYSICS By B.PREMLET
UNIVERSAL PHYSICS

[ath-har]

Audio Spotlighting
Liji Ramesan Santhi & Sreeja V
Electrical and Electronics Department
Mohandas College of Engineering and Technology

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Abstract
In the present world, distortion sound which was annoying to the people in the vicinity, an audio
spotlighting system was designed as a solution to one of life s many challenges. Audio spot
lighting is a very recent technology that creates focused beams of sound similar to light beams
coming out of a flashlight. By shining sound to one location, specific listeners can be targeted
with sound without others nearby hearing it. This acoustic device comprises a speaker that fires
inaudible ultrasound pulses with very small wavelength which act in a manner very similar to
that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam
moves through the air gradual distortion takes place in a predictable way due to the property of
non-linearity of air. This gives rise to audible components that can be accurately predicted and
precisely controlled. The targeted or directed audio technology is going to a huge commercial
market in entertainment and consumer electronics and technology developers are scrambling to
tap in to the market. Being the most recent and dramatic change in the way we perceive sound
since the invention of coil loud speaker, audio spot light technology can do many miracles in
various fields. In areas where headsets have previously been needed, why not use multiple audio
spotlights, so that customers can hear naturally

Introduction
Engineers have nearly struggled for half a
century to produce a speaker design with 20Hz
20000Hz capability of human hearing and also
produce a narrow beam of audible sound..
The directivity of any wave producing source
depends on the size of the source, compared to
the wavelength it generates. Inherent properties
of the air cause the ultrasound to distort in a
predictable way. The distortion gives rise to
frequency components in the audio bandwidth,
which can be predicted and precisely controlled.
By generating the correct ultrasonic signal, we
can create, within the air itself, essentially any
sound desired. The ultrasound column acts as an
airborne speaker, and as the beam moves through
the air, gradual distortion takes place in a
predictable way. This gives rise to audible
components that can be accurately predicted and
precisely controlled

Loud Speakers Vs Audio Spotlighting
All loudspeakers today have one thing in
common: they are direct radiating-- that is, they
are fundamentally a piston-like device designed
to directly pump air molecules into motion to
create the audible sound waves we hear. The
audible portions of sound tend to spread out in
all directions from the point of origin. They do
not travel as narrow beams which is why you
don t need to be right in front of a radio to hear
music. In fact, the beam angle of audible sound
is very wide, just about 360 degrees. This
effectively means the sound that you hear will be
propagated through air equally in all directions.

Conventional loudspeakers suffer from
amplitude distortions, harmonic distortion, phase
distortion, cross over distortion etc.
In order to focus sound into a narrow beam, you
need to maintain a low beam angle that is
dictated by wavelength. The smaller the
wavelength, the less the beam angle, and hence,
the more focused the sound. To create a narrow
sound beam, the aperture size of the source also
matters a large loudspeaker will focus sound
over a smaller area. If the source loudspeaker
can be made several times bigger than the
wavelength of the sound transmitted, then a
finely focused beam can be created. The problem
here is that this is not a very practical solution.
To ensure that the shortest audible wavelengths
are focused into a beam, a loudspeaker about 10
meters across is required, and to guarantee that
all the audible wavelengths are focused, even
bigger loudspeakers are needed, thus the low
angle beam can be achieved only by making the
wavelength smaller and this can be achieved by
making use of ultrasonic sound. Audio spotlight
looks like a disc-shaped loudspeaker, trailing a
wire, with a small laser guide-beam mounted in
the middle. When one points the flat side of the
disc in your direction, you hear whatever sound
he's chosen to play for you. But when he turns
the disc away, the sound fades almost to nothing.

Working
It's markedly different from a conventional
speaker, whose orientation makes much less
difference. PRO SOUND SYSTEM > Audio Spotlight >
AUDIO SPOTLIGHT TECHNOLOGY
The original low frequency sound wave such as
human speech or music is applied into an audio
spotlight emitter device. This low frequency
signal is frequency modulated with ultrasonic
frequencies ranging from 21 KHz 28 KHz. The

Point-'N'-Shoot Sound Makes Waves
Researchers have developed technology that can
project a beam of sound so narrow that only one
person can hear it. "Directed" audio sounds like
it's coming from right in front of you even when
transmitted from a few hundred meters away.
Inventors of the new "ventriloquist" technology
say it could provide an added dimension to
entertainment. The military, however, is
investigating using it to confuse opponents or
even inflict pain.
The Audio Spotlight is one of two competing
audio transmission systems that emit a one-foot
square column of sound that can only be heard
by people in its direct path. Joseph Pompeii, a
PhD student at the MIT Media Lab, decided to
develop it while working at audio company
Bose, which he joined at 16 as its youngest-ever
engineer.
output of modulator will be modulated form of
original sound wave. Since ultrasonic frequency
is used the wavelength of the combined signal
will be in the order of few millimeters. Since the
wavelength is smaller the beam angle will be

around 3 Degree, as a result the sound beam will
be narrow one with a small dispersion.
While the frequency modulated signal travels
through air, the non linear property of air, comes
into action which slightly changes the sound
wave. If there is a Change in the sound waves
new sound waves are formed within the wave.
Therefore new sound signal generated within the
ultrasonic sound wave will be corresponding to
the original information signal will be produced
within the ultrasonic sound wave. Since we
cannot hear the ultrasonic sound wave we only
hear the new sounds that are formed by non
linear action of air. Thus in an audio spotlighting
there are no actual speakers that produces the
sound but the ultrasonic envelope acts as
airborne speaker.

Components
Power Supply:
The audio spotlighting system works off dc
voltage. Ultrasonic amplifier requires 48V dc
supply for its working and low voltage for
microcontroller and other process management.
Frequency Oscillator:
It generates ultrasonic frequency signals in the
range of 21 KHz to 28 KHz which is required for
modulator of information signals.
Modulator
In order to convert the source signal material into
ultrasonic signal a modulation scheme is
The new sound produced virtually has no
distortions associated with it and faithful
reproduction of sound is freed from bulky
enclosures. There are no woofers or crossovers.
This technology is such a way that you can direct
ultrasonic emitter towards a hard surface a wall
for instance and the listener perceives the sound
as coming from the spot on the wall. The listener
does not perceive the sound as emanating from
the face of the transducer, but only from the
reflection of wall. For the maximum volume that
trade show use demands it is recommended that
the audio spotlight speaker more accurately
called transducer is mounted no more than three
meter from the average listener ears or five
meters in the air. The mounting hardware is
constructed with a ball joint so that the audio
spotlights can easily aimed wherever the sound
is desired.
required which is achieved through a modulator.
In addition error correction is needed to reduce
distortion without loss of efficiency
Audio signal processor:
Signal is sent to electronic signal processor
circuit where equalization and distortion control
are performed in order to produce a good
equalization signal.
Microcontroller:
A dedicated microcontroller circuit takes care of
the functional management of the system. In the
future version it is expected that the whole
process like functional management, signal
processing, double side band, modulation and
even mode of power supply would be effectively
taken care of by a single embedded IC.
Ultrasonic amplifier:
High efficiency ultrasonic power amplifier
amplifies the frequency modulated wave in order
to match the impedance of the integrated
transducers so that the output of the emitter will
be more powerful and can cover more distortion.
Transducer:
It is 1.27cm thick and 17 in diameter. It is
capable of producing audibility up to 200mwith
better clarity of the sound. It has the ability of
real time sound reproducibility with zero lag.
These transducers are arranged in the form of an
array called parametric array in order to
propagate the ultrasonic signals from the emitter
and thereby to exploit the non linearity property
of air.

Conclusion
Although the project didn t succeed, there are
several issues to be gained. It is really going to
make a revolution in sound transmission and the
user can decide the path in which audio signal
should propagate. It is going to shape the future
of sound and will serve our ears with magical
experience.
Reference
1. F Joseph Pompei:The use of airborne
ultrasonic for generating audible sound
beams- Journal of the Audio Engineering
Society
2. P J Westervelt, Parametric
Acoustic array-Journal of the
Acoustical society of America.
3. The past, present and Future of Audio Signal
Processing, IEE signal Processing
Magazine(pages 30-57,sept 1999)
4. silentsound.co.za-silent sound.
5. techalone.com-Audio Spotlighting
6. holosonics.com
7. Electronics for you- volume 40 (January
2008)
8. fileguruapps/audio_spotlighting_
iee paper(2009)

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Submitted by

VEERENDRA SHETTY T P


INTRODUCTION

Hi-fi speakers range from piezoelectric tweeters to various kinds of mid-range speakers and woofers which generally rely on circuits and large enclosures to produce quality sound, whether it dynamic, electrostatic or some other transducer based design. Engineers have struggled for nearly a century to produce a speaker design with the ideal 20Hz 20,000Hz capability of human hearing. When you listen to sound over loudspeakers, you don't have any control over where the sound goes. Sometimes you don't want it to go everywhere. Scientists have devised a way to solve that problem. They have figured out how to "steer" sounds by aiming them only where he wants them to go with a device they call Audio Spotlight.
Audio spot lighting is a technology that creates focused beams of sound similar to light beams coming out of a flash light. By shining sound to one location, Specific listeners can be targeted with sound without others nearby hearing it, i.e. to focus the sound into a coherent and highly directional beam. It makes use of non-linearity property of air.
Imagine projecting sound in a narrow beam, much like the light from a spotlight! In the past we were limited by sound invading all of the space surrounding the loudspeaker or sound source. Not anymore! With the Audio spotlighting Sound systems, you can put sound wherever you want. With a spotlight, when you step into the beam of light, you are clearly illuminated by the light. When you step out of the beam, you are lit only by the background light. Similarly you can t see the beam of sound, but when you step into it, you can hear the sound or narration inside! Step back out of the beam and the sound is gone! Stepping into the directional sound beam is like putting on a set of virtual headphones. You can now have several different soundtracks or musical styles co-exist in one small space, heard only by those who should.

The Audio spotlight developed by American Technology Corporation uses ultrasonic energy to create extremely narrow beams of sound that behaves like beam of light.Audiospotlight exploits the property of non-linearity of air. When in audible ultrasonic pulses are fired into the air, it spontaneously converts the inaudible ultrasound into an audible sound. A device known as parametric array employs the non-linearity of the air to create audible by products from inaudible ultrasound, resulting in extremely directive and beam like sound. This source can projected about an area much like a spotlight and creates an actual specialized sound distant from a transducer. The ultrasound column acts as a airborne speaker, and as the beam moves through the air gradual distortion takes place in a predictable way. This gives rise to audible components that can be accurately predicted and precisely controlled.

Sound from ultrasound is the name given here to situations when modulated
ultrasound can make its carried signal audible, without needing a receiver set. This
happens when the modulated ultrasound passes through anything which behaves nonlinearly
and thus acts intentionally or unintentionally as a demodulator.

For now, customers are testing out the technology for a variety of uses. But adoption
may be slow due to the cost of the system and the fact that each unit needs to be handmade.
Also, problems with creating low bass tones will keep Audio spotlighting systems out of
audiophiles for the present. On the other hand, this is not preventing Sony from incorporating
the technology in plasma screens for specialty applications. Widespread application of Audio
spotlighting could still be years away, but with companies like Sony interested, it can only
speed mainstream adoption of the technology.

HISTORY

History is replete with rival inventors battling one another to bring breakthrough creations to market. Howe and Singer over the sewing machine, Bell and Gray over the telephone, Edison and Swan over the light bulb.

Now, in that same tradition, two inventors Elwood Woody Norris of Poway, CA-based American Technology Corporation (ATC), and F. Joseph Pompei, of Watertown, MA s Holosonic Research Labs, have harnessed the same scientific principle to create competing directional-sound systems.

The technique of using a nonlinear interaction of high-frequency waves to generate low-frequency waves was originally pioneered by researchers developing underwater sonar techniques dating back to the 1960s. They called this device a parametric array. In 1975, an article cited the nonlinear effects occurring in air.

Over the next two decades, several large companies, including Matsushita, NC Denon, and Ricoh attempted to develop a loudspeaker based on this principle. They were successful in producing some sort of sound, with extremely high levels of distortion (>50%). This drawback caused the total abandonment of the technology by the end of the 1980's.

Later during the spring of 1996, Elwood Woody Norris one of the founders of American Technology Corporation was working blind to his competitor in the East within his garage in Poway CA. He felt that ultrasound could be used to create a sound beam. In July the same year, he felt that he had a breakthrough and he rushed off to the patent office, and patented the same.
In 1998, Joseph Pompei presented the paper The Use of Airborne Ultrasonic for generating Audible Sound Beams to the Audio Engineering Society, at their 105th
Convention in san Francisco CA. In 1999 he founded holosonic Research Labs or
Holosonics to commercialize this technology. He named it Audio spotlighting .

TECHNOLOGY OVERVIEW

The technique of using a nonlinear interaction of high frequency waves to generate low frequency waves was originally pioneered by researchers developing underwater sonar techniques in 1960 s. In 1975, an article cited the nonlinear effects occurring in air. Over the next two decades, several large companies including Panasonic and Ricoh attempted to develop a loudspeaker using this principle. They were successful in producing some sort of sound but with higher level of distortion (>50%). In 1990s, Woody Norris a Radar Technician solved the parametric problems of this technology.

Audio spotlighting is a paradigm shift in sound production based on solid principles of physics. Audio spotlighting technology projects a column of modulated ultrasonic frequencies into the air. These ultrasonic frequencies are inaudible by themselves. However, the interaction of the air and modulated ultrasonic frequencies creates audible sounds that can be heard along a column. This audible acoustical sound wave is caused when the air down-converts the ultrasonic frequencies to the lower frequency spectrum that humans can hear.

Audio spotlighting technology works by emitting harmless high frequency ultrasonic tones that we cannot here. These tones use the non-linearity (fig 3.1) property of air to create new tones that are within the range of human hearing. The result is an audible sound. The acoustical sound wave is created directly in the air.

In a Audio spotlighting system, there are no voice coils, cones, crossover networks or enclosures. The result is sound with a potential purity and fidelity which we attained never before. Sound quality is no longer tied to speaker size. The Audio spotlighting system holds the promise of replacing conventional speakers in homes, movie theatres, and automobiles everywhere.

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[sharonsden]

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ABSTRACT
Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Joseph Pompei s Holosonic Research Labs invented the Audio Spotlight that is made of a sound processor, an amplifier and the transducer. The American Technology Corporation developed the Hyper Sonic Sound-based Directed Audio Sound System. Both use ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.
The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc. Thus audio spotlighting helps us to control where sound comes from and where it goes.

Advantages
Attract and excite shoppers with sound, without adding noise.
Maintain peace and quiet, while still providing sound.
"Illuminate" products with sound.
Allow multimedia in difficult or sensitive areas.

Western Union at Times Square
Western Union's landmark location in Times Square is not a typical money transfer center. While all of the regular services offered by Western Union are available, the location also serves as a promotional and informational center for the company. This ability to provide two completely different experiences in one large open space is enabled by the use of Audio Spotlight technology.
A large video wall, controlled by an interactive touch screen kiosk, displays information about the company's various philanthropic activities. Sound is provided by an Audio Spotlight speaker, delivering the content only to the intended listeners, while enabling the customers and staff to do business in a quiet, professional atmosphere just a few feet away.

In Store Advertising
A major convenience store chain contacted us because they were having several issues with adding sound to their in-store advertisements. They had tried traditional speakers, and other so-called "directional" sound systems, but were unable to provide sound without bothering their customers while frustrating and distracting employees. Store management was concerned about poor employee morale and attention, and sought a better solution. Holosonics resolved all of these issues by providing the chain with Audio Spotlight systems, which were able to deliver concise, targeted advertising messages while maintaining a peaceful, pleasant environment for the shoppers. The results have been nothing short of perfection, and the systems are now featured in numerous store locations across the USA.

Digitas
Digitas, a major advertising firm, decided to utilize their corporate lobby to showcase various examples of their work. They needed to provide a complete multimedia experience with sound and video, but only to a specific audience, and without disturbing nearby visitors or employees. Rather than using traditional loudspeakers, they employed Audio Spotlight systems, and are now able to provide an engaging multimedia experience to those who are interested, while preserving a professional atmosphere.

Cisco Systems Cisco Systems called us with an urgent problem. Noise in their visitors' center was disturbing their guests, and the complaint came straight from top management. Four plasma screens had been installed in one small room, each with custom-designed, interactive multimedia content. With only traditional loudspeakers, every guest was bombarded with sound from all four stations, creating a distressing environment for their clients and Cisco's management. The executive originally demanded that these displays be removed entirely, but instead Cisco called us, and we offered a better solution. We installed a single Audio Spotlight disc over each display, and used a standard ball-socket mount to aim each disc directly at the listening position in front of each screen. With sound created by Audio Spotlight systems, only those interested in interacting with the display hear the sound, and the rest of the room remains peaceful, quiet, and professional for everyone.

Incredible Connection
Located in the massive Gateway Shopping Center in Durban, South Africa, Incredible Connection is a computer and electronics mega store that has all the latest technology. For their gaming section, Incredible Connection wanted to offer their customers a truly unique experience. They contacted local reseller Silent Sound and soon had an Audio Spotlight system installed above each gaming kiosk. The systems, installed above each gaming kiosk, allow customers to play the latest games with their own sound while leaving the other areas of the store unaffected.

Best Buy
Best Buy is putting Audio Spotlight systems to use in a variety of applications in their retail stores, including DVD sales and promotion, kiosks, and product "beacons". The retail chain installed several Audio Spotlight systems in the "Family Fun Zone" section of one of their retail stores. Each system corresponds to a television that can be seen and heard in one discrete location. Shoppers outside of the zone remain completely unaffected by the sound. The system allows retailers to create a unique and isolated atmosphere within a large noisy environment.

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[SHAJAHAN]

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audio spotlighting full report

An Alternative Approach
P. Hong, IMTC, Georgia Institute of Technology

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Abstract
The purpose of this project was to design a system that would actively direct audio in desired directions and locations. Although there already exist proven methods of achieving this goal, including ultrasound modulation in [8] and sound direction by parabolic dishes, a digital signal processing (DSP) and antenna theory approach was developed for this system.

Introduction

The applications for a directive sound system range greatly from public address systems to personal notification systems in a room. Because of the many potential applications, system development becomes a higher priority than before. Here, the system to be developed consists of a computer equipped with an 8 audio output soundcard and the amplifiers and loudspeakers associated with each audio channel. The computer uses a multi-track audio program to playback individual sound files on each channel. These sound files were generated by MATLAB with delays and gains dependent on the loudspeaker positions as well as the desired optimal observation point coordinates within a specified room which can also correspond to a direction depending on the equations used in MATLAB and whether a near-array or far-array approach is desired. This system differs greatly from the aforementioned systems for directing sound. To briefly explain: The ultrasound modulation system simply does that, it modulates a carrier wave that operates in the ultrasound frequency range with the desired audio signal. By doing this, the system takes advantage of the non-linearities of air at those frequencies thereby causing demodulation of the desired signal for hearing. This scheme provides very high directivity as noted in [8]. The primary disadvantage is the damage it causes to the human auditory system although this is currently being studied and will hopefully be circumvented in the future. The parabolic dish approach essentially is an antenna approach. Just as in antenna applications, a relatively omni-directional loudspeaker is placed at the focal point of a parabolic dish, pointing towards it. Consequently, when a desired sound is sent to the loudspeaker, it acts like a point source letting out a spherical wave to reflect off of the dish creating a directive beam of sound. This system has already been implemented by several companies. Its primary disadvantage is its bulk; the parabolic dish has to be relatively large in order to accommodate the longer wavelengths of lower frequencies and to provide a suitably sized listening area. Both systems also require mechanical means to change the location they are illuminating with sound. The system we wish to develop will not require mechanical means for steering and will not be particularly bulky either. Steering is controlled by the delays of the signal to each loudspeaker, i.e. the steering is electrically controlled. A diagram of the set up can be seen in Figure 1: Diagram of System Set Up.

[divyam]

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INTRODUCTION

What is audio spot lighting
Invented by Dr. F. Joseph Pompei.
It is the Production of focused beams of Sound
Combination of Non-Linear Acoustics & Fancy Mathematics.
Uses Ultra-sonic Energy to create Narrow beams of sound
Non Linearity of the AIR aid the device for its working
Device used: Parametric Array

How does ordinary sound system work
Piezoelectric Tweeters.
Speakers.
Woofers etc.


What ordinary audible sound & Conventional Loud Speakers lack


Difficulty in reproducing clean bass.
Has to rely on a large woofer/enclosure combination for it.
THEORY

Audio spot lighting is a technology that creates focused beams of sound similar to light beams coming out of a flashlight.
By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it.
The Audio Spotlight & Hyper Sonic Sound Technology (developed by American Technology Corporation), uses ultrasonic energy to create extremely narrow beams of sound that behave like beams of light.

WORKING
Low Beam Angle is required to focus the Sound.
Smaller the Wave length, Lesser the Beam Angle.
Another way to Focus sound is to increase Aperture size of Speakers(10m dia for 20Hz) practcally difficult.

Technology Overview

Developed by American Technology Corporation
Uses ultrasonic energy to create extremely narrow beams of sound that behave like beams of light.
Ultrasonic sound has very small wavelength in the millimeter range and lies beyond the threshold of human hearing

NON-LINEARITY OF AIR
When inaudible ultrasound pulses are fired into the air, it spontaneously converts the inaudible ultrasound into audible sound tones.
A device known as a parametric array employs the non-linearity of the air to create audible by-products from inaudible ultrasound, resulting in an extremely directive, beamlike wide-band acoustical source.
The ultrasound column acts as an airborne speaker
Human speech, as well as music, contains multiple varying frequency signals.
Then came the idea of using pure ultrasound signals as a carrier wave.
Airborne ultrasounds of
28kHz are envelope-
modulated with audio
signals. Inherent non-linearity
of the air works as a
de-modulator.
Thus de-modulated sounds impinge on our eardrums. We can hear those sounds!
Similar to the idea of Amplitude Modulation (AM).
The speech and music signals are mixed with the pure ultrasound carrier wave, and the resultant hybrid wave is then broadcast.
Berktay s equation holds strong here P2(x,t)=KPc2-2/ t2(E(x,t)

SPECIAL FEATURES OF AUDIO SPOTLIGHT


Creates highly FOCUSED BEAM of sound

Sharper directivity than conventional loud
speakers using Self demodulation of finite
amplitude ultrasound with very small
wavelength as the carrier

Uses inherent non-linearity of air for
demodulation

[abinay]

[attachment=5408]
audio spotlighting full report

ABSTRACT


Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Joseph Pompei s Holosonic Research Labs invented the Audio Spotlight that is made of a sound processor, an amplifier and the transducer. The American Technology Corporation developed the Hyper Sonic Sound-based Directed Audio Sound System. Both use ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.

The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc. Thus audio spotlighting helps us to control where sound comes from and where it goes!

[roshshankar]

[attachment=6759]

AUDIO SPOTLIGHTING


ABSTRACT

Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Joseph Pompei s Holosonic Research Labs invented the Audio Spotlight that is made of a sound processor, an amplifier and the transducer. The American Technology Corporation developed the Hyper Sonic Sound-based Directed Audio Sound System. Both use ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.

The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc. Thus audio spotlighting helps us to control where sound comes from and where it goes!

[ammarghamian]

[attachment=5395]

AUDIO SPOTLIGHTING

ABSTRACT
Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Joseph Pompei s Holosonic Research Labs invented the Audio Spotlight that is made of a sound processor, an amplifier and the transducer. The American Technology Corporation developed the Hyper Sonic Sound-based Directed Audio Sound System. Both use ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.

The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc. Thus audio spotlighting helps us to control where sound comes from and where it goes!

[rvd]

[attachment=6797]
AUDIO SPOTLIGHTING..

Deepika Bhatnagar
G.Priyanka

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ABSTRACT :
Audio spot lighting is a very recent technology that creates focused beams of sound similar to light beams coming out of a flashlight. By shining sound to one location, specific listeners can be targeted with sound without others nearby hearing it. It uses a combination of non-linear acoustics and some fancy mathematics. But it is real and is fine to knock the socks of any conventional loud speaker. This acoustic device comprises a speaker that fires inaudible ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column. The ultra sound beam acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in a predictable way due to the property of non-linearity of air. This gives rise to audible components that can be accurately predicted and precisely controlled. Audio Spotlight is made of a sound processor, an amplifier and the transducer. It uses ultrasound based solutions to beam sound into a focused beam. Audio spotlight can be either directed at a particular listener or to a point where it is reflected.The targeted or directed audio technology is going to a huge commercial market in entertainment and consumer electronics and technology developers are scrambling to tap in to the market. Being the most recent and dramatic change in the way we perceive sound since the invention of coil loud speaker, audio spot light technology can do many miracles in various fields like Private messaging system, Home theatre audio system, Navy and military applications, museum displays, ventriloquist systems etc. Thus audio spotlighting helps us to control where sound comes from and where it goes!