Control of Parametric Amplification Using the Nonlinear Vibration of Bubbles Under Water

Abstract

Strong nonlinearity appearing in bubble vibration is proposed to control parametric amplification over a wide range. The equivalent nonlinearity parameter βd for the difference frequency sound of the parametric array in bubbly medium is defined. Bubble condition where βd is controllable over a wide range by varying bubble density are theoretically discussed and experiments are performed. It is confirmed that SPL of the difference frequency can be easily controlled by the bubble conditions. Waveform distortion is clearly observed on a time profile at a short distance from the sound source.