Looking through some old camcorder tape, I found this footage of a trip down to our local river on a sunny winter day, when I found a quiet stretch of water where the sunlight showed “shadows” of the eddies, and I could watch them spinning past.

While I was filming, a mother and her child walked by and the boy asked me what I was doing – the conversation’s caught on the soundtrack.

My idea was an instrument which makes sound by listening to the unplugged inputs of the computer’s soundcard (just listening to very, very quiet hiss), then feeds that back on itself; it also listens to the loudness of its output, turning the feedback down if it’s getting too loud, and up if it’s dying away altogether. I dropped a couple of filters into the loop too, to colour the sound.

What’s nice about the idea is that it’s negative feedback:

Output too loud? Turn it down. Output too quiet? Turn it up.

Which controls positive feedback:

Apply reverb to input. Send some of the output back to the input.

What I didn’t quite expect was how beautiful it would sound:

Download audio file (Dave_Pape_-_Reverb_Experiment_01.mp3)

It’s a little loud at the beginning, but after a quick tweak of its sensitivity to loud signals, it began to produce a rolling flow of gorgeous harmonics, which even managed to sound musical every so often.

So when there’s another window of sound design opportunity, I think I’ll have another play with it.

It felt quite medieval: it’s a big, castle-like block of flats, and it was as if the residents were defending it.

Here’s the recording – enjoy.

Download audio file (croydon_march_2006.mp3)

The recording keeps my memory fresh, but I’m shocked that it happened two years ago. I should record more often…