We have scaled this up to two full octaves and allow the non-musical to play tunes.
We use 25 black and white tubes in the pattern of a piano keyboard to build the instrument itself creating two octaves of notes. The second octave hugely increases the number of tunes you can play.
This consists of a laser pointing at a light sensor across a gap. The light sensor is connected to a speaker, so if you move an object like a piece of mesh across the gap it will block the light many times a second you produce sound.
You can experiment with moving different objects with different patterns of holes, such as sieves, fabrics, combs etc, at different speeds to see what sounds they make.
Wheels with teeth or slots in them make a wonderful noise.
As well as seeing the relationships between speed of vibration and pitch, and size of vibration and volume, this allows you to see differences in the sounds you make. The different vowel sounds look different, as do 's' sounds, adult male voices produce much more messy waveforms than do children's voices.
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