Aether Drift

There are plenty of ways to introduce audible modulations into a light source. You can modulate its power supply with a signal, you can use vibrating mirrors, you can burn old floorboards nearby (see an earlier post below), you can flail your arms in front of it - the possibilities are legion.

Alternatively, it can be made to interfere with itself. This works best with laser light as it is coherent (all the waves leave the laser in phase) and is surprisingly easy to do. Try pointing a laser at a photodiode and get the beam to reflect back into the laser aperture, which, if I'm not mistaken, produces an interference pattern through tiny differences in the reflected beam paths. What you should hear is little squeaky noises, which are the interference fringes (light/dark patterns) whizzing about as the muscles in your fingers twitch and the photodiode or laser moves.

A more complicated way is to build an interferometer like this one, which is based on the Michelson-Morley experiment of 1887, except much simplified. Essentially it splits a laser in two using a half silvered mirror, and then recombines the two beams. Nanoscopic changes in the length of the two paths will register as a shift in the interference pattern (there's a nice flash demo in the link above). My fellow traveler Mathew Chadwick came up with the idea that if an interference pattern can be seen to change due to whatever forces are acting upon the apparatus, then maybe there's lots going on which can be revealed through sonification, ie, placing photodiodes into the beam paths so you can hear what's happening. He wasn't wrong.

This is a kind of abuse of an old and important experiment, in so far as the idea normally would be to isolate the thing from all vibration (Michelson's second attempt involved floating the whole thing in a trough of mercury). My engineering skills are somewhat basic, or rather, I don't have that useful personality quirk that many engineers have where everything has to be just right, and therefore the Fisher-Price nature of my interferometer means that it's not as sensitive as it might be. The laser physicists among you will behold my photo above and wince.

The recording here is the hi-lights of about one hour during a group exhibition opening party in a church in Vauxhall, London, UK, 2003. I have plans for a much larger and more sensitive one - in green.

The thing that started it all...

In 2000 I was lucky enough to find myself in Moscow and in the company of an authority on early electronic musical instruments (you can find his invaluable website here). To be brief, he introduced us to a wonderful chap called Stanislav Kreichi who is the proud keeper of this one-of-a-kind drawn sound synth - the ANS.






Essentially it plays what you draw in an up/down=pitch, left/right=time way. For a more detailed description, have a look at the wiki, a fair chunk of which I wrote. The other image is of a score which I have a recording of somewhere...
I ended up recording quite a bit of material on the ANS, and it completely changed my outlook on how sound could be generated and controlled. Quoting from a paper I presented on Photophonics in June:

It has a killer combination of gesture, microtonality, immediacy, temporal flexibility and sonic beauty, which makes it unique. It can be read in terms of the still and the moving image and seems to come from a culture outside of normal artistic, scientific or industrial production – like a cross between a printing press and a jukebox. I think it entirely appropriate that it was used by the composer Edward Artimiev as the voice of the intelligent ocean in Tarkovski’s Solaris.

Here's a short piece I drew on a return trip in spring 2001...