Alternative ways of interacting with sound

When I was young, I tried to build a modular syntesizer, one there one could make any sound imaginable (for a really crazy modular, check out extensive interview with Joe Paradiso, MIT).

However, you want quality knobs, and they costs like 60 kr/each, complete with knobs, frontplates and so on. The whole case would be very expensive and actually, you need a lot of knobs. And the syntesizer would not start to be fun until you had at least a half dozen effects and generators. That would be a huge investment. And since I had some nice softwares at hand, the interaction part would be the more important than the sound genereating one (since that could be solved in my computer).

I actually sketched at least a hundred sketches of interaction possibilities, some optical, some knobs and others even more freaked out (inspired by the group 8Tunnel2, who made music by slicing broccoli with electronic knifes...).

The light interaction part was really fruitful. Light is easy to mix (an important property), and can be led in plastic fibers, leds and photosensors are indeed unexpensive. It can also have different colors, and be filtered through colored plastic. It's also visible, nondangerous and can be shut of by a hand or any non-transparent object. Building gain-like things would be very easy (especially compared to the knobs). Negative aspects is that it can not be "negative" in an easy way, you cannot show negative voltages with light (because that would be the negative absence of light). You need some kind of microphones to convert light to electricity and "sound" again (in my world, all sound is electric, loudspeakers are usually not that intresting to me).

However, I eventually realized that the ac in the walls would put a nice 50 Hz "light hum" through light bulbs in all the sounds if the box wheren't totally sealed. However, one could work with it bit more. I will explore it further.