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Bubble piano

Injecting bubbles in a liquid makes "noise"

When a gas is injected into a liquid, bubbles appear at the nozzle of the pipe. When they come out, these bubbles are not at equilibrium: they oscillate at their eigen frequency, the Minnaert frequency. As this frequency is in the audible range for millimetric bubbles (about 3 kHz for a 1mm-radius bubble), the injection can be heard, as demonstrated in the video. Here an hydrophone has been used to amplify the sound. Note that, contrary to what is often thought, the noise does not come from the bubble bursting at the surface.

By varying either the diameter of the nozzle or the gas flow rate, one can change the size of the bubbles, and thus the frequency of the sound. Hence one can tune the frequency to obtain the wanted note, and build a bubble piano. The tune below has been brought together with the sounds of bubbles of different radii.

WAV - 97.1 kb
"Ode to joy" with bubbles

Postscript :

Sound acquisistion by E. Montessoro and R. Patey

Contact : Published on / Publié le 18 January 2011