Learning and teaching acoustics through bubbles

By a lark, I started my acoustics career as a graduate student studying a single big bubble in the form of the combustive sound source. By at least the luck of being in a certain place at a certain time, I finished my graduate education by studying bubbles in the form of the acoustics of bubbly liquids. It turns out that the subject of bubbles provides an excellent lens through which to learn and teach acoustics. One starts with lumped element approximations which lead to simple harmonic oscillators and resonance. You can study the bubble oscillator as linear system and encounter increasingly complex nonlinear behavior at comparatively low amplitudes. A bubble is a source of sound initially modeled as a simple spherical source and can of course behave as a spherical scatterer. Add one or many bubbles and one can study more complex scattering and propagation that includes dispersion and loss. Along the way one encounters effective medium theories of varying complexity and statistical descriptions of acoustic phenomena. There are also applications that require inference and inverse techniques. You can even apply a model of a single bubble to study the expansion and contraction of the universe. Examples of these including demos and videos will be presented.