AUDIO SPOT LIGHTING

CONTENTS INTRODUCTION TECHNOLOGY OVERVIEW RANGE OF HEARING WOKING BEAM DISPERSION ARCHITECTURE MODES OF LISTENING ADVANTAGES & DISADVANTAGES APPLICATIONS FUTURE OF AUDIO SPOT LIGHTENING CONCLUSION

WHAT IS AUDIO SPOT LIGHTING? Audio spot lighting is a very recent technology that

creates focused beams of sound similar to light beams coming out of a flashlight. Specific listeners can be targeted with sound without others nearby hearing it. It makes use of non-linearity property of air.

Uses ultrasonic energy to create extremely narrow beams of sound that behaves like beam of light.

Audio spot light is developed by American Technology Corporation.

TECHNOLOGY OVERVIEW Audio spot lighting works by emitting

harmless high frequency ultrasonic tones that human ear cannot hear.

To produce highly focused audio signal we use loud speakers with larger aperture size.

Parametric array employs the non linearity of the air to create audible by products from inaudible ultrasonic sound , resulting in extremely directive and beam like sound.

As the beam moves through the air gradual distortion takes place in a predictable way. This give rise to audible components that can be accurately predicted and precisely controlled.

RANGE OF HEARING

Human ear – 20 Hz to 20,000 Hz.

No single loud speaker can operate efficiently over such wide range of frequencies.

By using this technology it is possible to design a perfect transducer which can work over a wide range of frequency which is audible to the human ear.

WORKING 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 range with wavelength of few millimeters.

Since the wavelength is smaller the beam angle will be around 3 degree, as a result the sound beam will be a narrow one with a small dispersion.

WORKING…

AUDIO SPOTLIGHTING EMITTER

WORKING.. Due to the nonlinearity property of air new

sounds are formed within the wave.

The new frequencies (sounds) will be added into the sound wave by the air itself.

The new sound signal generated will be corresponding to the original information signal with a frequency in the range of 20 Hz to 20 KHz .

Since we cannot here the ultrasonic sound, we

only hear the new sounds that are formed by the non linear action of the air

COMPONENTS OF AUDIO SPOTLIGHTING SYSTEM

Power Supply. Frequency oscillator. Modulator. Audio signal processor Microcontroller. Ultrasonic amplifier. Transducer.

1. Power Supply: works off DC, ultrasonic amplifier requires 48v for working and low voltage for other components.

2. Frequency oscillator: generates ultrasonic frequency signals (21,000 Hz to 28,000 Hz).

3. Modulator : convert the source information into ultrasonic signals. In addition, error correction is needed to reduce distortion without loss of energy.

4.Microcontroller: takes care of the functional management of the system.

5. Audio signal processor: The audio signal is sent to an electronic signal processor circuit where equalization, dynamic range control, distortion control and precise modulation are performed to produce a good quality sound signal.

6. Ultrasonic amplifier: High- efficiency ultrasonic power 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 distance.

7. Transducer: It is 1.27 cm thick and 17’’ diameter. Produces audibility up to 200 meters with better clarity of sound.

Has the ability of real time sound reproduction with zero lag.

These transducers are arranged in form of an array called parametric array in order to propagate the ultrasonic signals from the emitter and thereby to exploit the nonlinearity property of air.

MODES OF LISTENING

Direct mode Projected mode

Direct Mode: Requires a clear line of approach from the

sound system unit to the point where the listener can hear the audio.

To restrict the audio in a specific area this method is appropriate.

Projected or Virtual mode: For this mode of operation the sound beam from an emitter is made to reflect from a reflecting surface .

A virtual sound source creates an illusion of sound source that emanates from a surface.

This method is appropriate when we want to send the information to a large number of people.

ADVANTAGES

Small size Single source Ultimate control in audio placement/Highly

directional Minimizes noise pollution Ease of installation Lowest maintenance cost Reduced feedback

DISADVANTAGES

Lack of mass production. i.e, each unit must be handmade.

The most common form of distortion is clipping. An LED on top of the Audio spotlight system reports clipping, which is also perceptible to the listener as a kind of a 'chirping' effect. If any signal produces distortion, the input level of the source is reduced until perceptible distortion is eliminated.

APPLICATIONS

Automobiles Retail sales Safety officials Public announcement Entertainment system Museums Military applications Political

FUTURE OF AUDIO SPOT LIGHTENING

Holds the promise of replacing conventional speakers. It allows the user to control the direction of propagation of sound. Will force the people to rethink their relationship with the sound. It really “put sound where you want it”.

CONCLUSION

Audio spotlighting is really going to make a revolution in sound transmission and the user can decide the path in which audio signal should propagate. Due to the unidirectional propagation it finds application in large number of fields. Audio spotlighting system is going to shape the future of sound and will serve our ears with magical experience…

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