INTRODUCTION• Audio spot lighting is a very recent technology that creates a focussed beams of sound similar to light beams coming out of a flash light.• Specific listeners can be targeted with sound without others nearby hearing it.• It makes use of non-linearity property of air.
HOW IS THE SOUND FOCUSED INTO ANARROW BEAM???• Maintain a low beam angle that is dictated by wavelength.• The smaller the wavelength,the less the beam angle, the more focussed will be the sound.• The audio spot light uses ultrasonic energy to create extremely narrow beams of sound . FOCUSED BEAM OF SOUND
• 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 controlled….. DEMONSTRATION OF HOW INVISIBLE ULTRASOUND WAVE WORKS
TRANSDUCER: Thesetransducers are arranged in form of an array called parametric array in order topropagate the ultrasonic signals from the emitter and thereby to exploit the nonlinearityproperty of air.
ADVANTAGES•Can focus sound only at the place you want.•Ultrasonic emitter devices are thin and flat .•The directed sound travels much faster .•Dispersion can be controlled.•Highly cost effective and longer life span.•Requires same power as required for regular speakers.•There is no lag in reproducing the sound…..
CONCLUSION Even the best loudspeakers are subject to distortion and their omni directionsound is annoying to the people in the vicinity who do not wish to.the audiospotlight will force people to rethink their relationship with sound.audiospotlighting really“PUT SOUND WHERE YOU WANT IT”
REFERENCE1) F. Joseph Pompei. The use of airborne ultrasonics for generating audible sound beams.Journal of the Audio Engineering Society, P. J. Westervelt. Parametric acoustic array.Journal of the Acoustical Society of America. 2)Thomas D. Kite, John T. Post, and Mark F. Hamilton. Parametric array in air:Distortion reduction by preprocessing. Journal of the Acoustical Society of America.3) Jacqueline Naze Tjotta and Sigve Tjotta. Nonlinear interaction of twocollinear,spherically spreading sound beams.4) www.silentsound.co.za – Silent sound.5)www.wikipedia.org - Sound from Ultrasound.6) www.howstuffworks.com7)www.techalone.com-audio spotlighting.8)www.holosonics.com9)Electronics for you-vol.40 January 2008.