Kai Lab
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Laser Microphone

Laser microphone - An exploration of hearing into the unknown.

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Laser Microphone acts like a microscope for sound, amplifying the physical vibrations of tiny objects that are otherwise too quiet to hear.

In the normal world, when an A440 tuning fork is hit, it produces the musical note A. This can easily be heard by the human ear because the physical size of a tuning fork allows the sound to be projected at a detectable amplitude. A smaller piece of metal also vibrating at 440 Hz will not be audible to the naked ear because of its weaker amplitude. In this case, Laser Microphone can still “see” the tiny vibrations of the metal at 440 Hz and will project the note A to the user through the headphones or speakers.

This installation stretches far beyond tuning forks, and has been used to hear phenomena such as the movement of insect wings, water spray and the movement of bubbles.

Method

A laser that is an intense coherent light source acts as an excitation device to illuminate an acoustic event. Light reflects off the vibrating object at the centre and can be either scattered on to or away from the sensor, depending on the recording angle. The varying light intensity is picked up by the sensor and is amplified and filtered. The frequency of the on/off pattern created by blocking the laser from reaching the sensor is converted into an audio signal that can be fed into any standard sound card. As it is set up above, acoustic vibrations in line with light are being detected. However, it is also possible to record from reflected beams also, as shown in the renders below.