Presented By: Anjali Garg ‘ECE’ VII Sem (O )

INTRODUCTION

HISTORY Under water sonar technique-non linear interaction of high frequency waves to generate low frequency waves. Dr.F.Joseph Pompei-the master mind.Holosonics Research lab-1999

Size of the source compared to its wavelength i.e. a large loud speaker will be more directive than a small loudspeaker. Audible sound waves have wavelengths ranging from few inches to several feet-and sound generally propagates omni directio nal. No amount of phasing, focusing, shading,or other method can overcome this fundamenta l limitations. LIMITATIONS

For example:-A 16 inch loud speaker panel at 1 khz mounted six feet overhead, two people would have to stand seven feet apart for 20db isolation where as ultra sonic technique provides same degree of isolation standing at merely 2 feet apart.

Technology  Nonlinear acoustics techniques to create sound literally in mid air using the non linear action of ultra sound

Audio spotlighting exploits the property of non-linearity of air. Resulting in an extremely directive, beamlike wide-band acoustical source. When inaudible ultrasound pulses are fired into the air, it spontaneously converts the inaudible ultrasound into audible sound tones. This source can be projected about an area much like a spotlight, and creates an actual spatialized sound. Making sound from “ultrasound”……..

BLOCK DIAGRAM

Components

Contd…

DIRECTED AUDIO Direct sound at a specific target, creating a contained area of listening space which is called “Direct Audio”. PROJECTED AUDIO Bounce off a second object, creating an audio image, which the listener perceives as the source of sound,c alled as “Projected Audio”. Modes of listening

APPLICATIONS  Museums and galleries -It provides localised sound for those who wish to hear it and quiet for every one else. Chicago cultural center, Boston museum of science, San Diego zoo, museum of South Australia.

 Retail shops:- Provide targeted advertising at the point of purchase.  Public announcement:- Highly focused announcement in noisy environment such as airports, traffic intersections,s ubways.

 Entertainment System:- Home theatre systems will soon be seen with this technology.  Automobiles:- Beam alert signals can be directly from an announcement device in the dashboard to the driver.

 Consumer locations:- Hair sallons and music stores to pamper the customers.

CONCLUSION Force the people to rethink their relationship with sound. It “puts the sound where you want”. “A REAL BOON TO THE FUTURE

REFERENCES

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