Monday, 28 December 2009
Twang on a can
Here, as unwisely promised yesterday, is a clip of me twanging the ring-pull of an aluminium fizzy drink can whilst simultaneously filling it with water. What do you think happens to the pitch of the note?
My own, subjective and non-scientific, opinion is that the pitch stays the same. The note seems to get higher because the upper harmonic partials are increasingly favoured as the can fills. If I were to blow the can like a flute then I would hear the air inside vibrating. Less volume of air, as the water replaces it, means a gradual rise in pitch. When I twang the can it is the can I hear resonating. The water dampens (no pun intended - 'deadens' might be a better word) the sound of the lower partials.
Today I went for a long walk by the sea so no sonic experiments. But tomorrow I shall continue to explore the seasonal debris and make some more rubbish instruments. If you would like to join in then hang on to all sizes of bottles, both glass and plastic, tin cans of various types, wrapping paper and anything else you think might produce a noise.