Video: Laser/smoke microphone promises the world's most accurate sound capture
By Loz Blain
September 23, 2009
The quest for ever more realistic sound reproduction seems set to move to a whole new level. Traditional microphones convert sound to electrical signals by measuring the deflections that sound vibrations cause in a diaphragm. But each diaphragm has its own weight, inertia and resistance, which colors the sound that gets recorded. So American digital audio pioneer David Schwartz, who invented the MP3 sound format, has come up with a novel new type of microphone that virtually eliminates the microphone's mechanical interference with the sound. The laser/smoke microphone uses a laser to measure the deflections that sound makes in a steady stream of smoke - which is virtually weightless. Prepare for a new wave of high-fidelity microphone technology.
Modern music may well be reaching new depths of artistic value, but if David Schwartz has his way, these new depths will be plumbed in higher fidelity than ever before.
Schwarz's smoke/laser microphone, currently at a very rough first prototype stage, eliminates the mechanical interference that colors the way traditional microphones process sound waves into electrical signals.
A laser beam is passed through a column of smoke to detect the deflections that sound waves cause in the smoke particles. As each smoke particle is virtually weightless, the theory is that they will deflect in ways that much more closely follow the contours of the original sound wave.
Check out the video below to see how it works in more detail:
Schwartz says he believes the laser/smoke microphone will produce a high-quality base sound from which other tones can be extracted if producers wish to mimic the sound qualities of existing diaphragm mics: "The color that certain microphones bring can be fantastic," he says. "The problem is, you can't have all of them, all of the time, meaning that all music recording is a compromise of some sort. With Laser-Accurate technology, all the tonal processing would take place after the sound is converted to a voltage, not during the act of recording it."
The microphone is currently in a very early prototype stage, but Schwartz is already able to take a low-quality signal from it. See below:
The use of light in sound transduction isn't new - in fact, it can be traced at least as far back as Leon Theremin's infrared remote eavesdropping system in 1947, which used an infrared beam to detect the sonic vibrations in glass windows. More modern surveillance laser mics work by measuring the vibrations in any surface that is free to vibrate with the sound waves.