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The ‘inversion’ we would now like to undertake would be to obtain the bubble population size distributions from the acoustic information. In fact, in the last slide we just did this in a qualitative way by comparing the relative natural frequencies of any bubbles we can identify. However we may wish to do this in a quantitative way, when the exponentially decaying sinusoids generated by various bubbles might overlap or be hidden in noise (and so not be as readily identifiable as on the last slide). To do this we need a model of how the bubble generates the sound. That model is a lightly damped harmonic oscillator, because we have seen from the previous slides that the bubbles produce a pressure emission which to first order resembles the exponentially decaying sinusoid that is characteristic of the lightly damped oscillator. To summarise in note form:

Inversion: Obtaining bubble population size distributions from the acoustic information
Need model.....

	.......Lightly-damped harmonic oscillator

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