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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.
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!
Imagine you could point the same way you can point light with, say, a flash light. Suppose speakers existed that could send focused beams of sound where ever thy pointed. You could speak in to a megaphone and send the sound to a single person. Or you could have five types of music playing on the same dance floor. You wouldn’t have to worry about turning the music down at night to keep the neighbors happy, so long as you didn’t point it in their direction. Thanks to recent advancement in audio engineering, the kinds of products may soon be a reality. Researchers have discovered a way to project acoustic waves as thin beam of sound: step into the beam and projected sound fills your ears.
Directional audio is a technology that creates-focused beams of sound, similar to the light beam coming out of a flashlight. The technology that powers this is known as audio spotlighting. It uses a combination of non-linear acoustics and some complex mathematics in order to focus sound into a coherent and highly directional beam. It is under development in Holosonics Research Labs and the American Technology Corporation.
Properties of audible sound:
• The human hearing ranges from a frequency of 20Hz to 20 KHz.
• Wavelength varies between 2cm to 17m.
• Beam angle – 360 degrees.
The audible portion of sound tends to spread out in all directions from the point of origin. The beam angle of audible sound is very wide, just about 360 degrees. This means the sound that you hear will be propagated through air equally, in all directions, which is why you don’t need to be right in front of a radio to hear the music.
In order to focus sound into a narrow beam the requirement is:
1. A low beam angle
-The smaller the wavelength, the lesser the beam angle and hence more focused the sound. The human hearing ranges from a frequency of 20Hz to 20 KHz. Therefore the audible sound is mixture of signals with varying wavelength between 2cm to 17m. Except for very low wavelength, just about the entire audible spectrum tends to spread out at 360 degrees.
2. Large aperture size
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. But this is not a very practical solution.
This is where the ultrasound came to the rescue.
PROPERTIES OF ULTRASOUND
- The frequency ranges above 20 KHz
- The wavelength is less than 2crn
- Small beam angle hence highly coherent and directional.
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
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