Abstract by Brian Patchett
Physics and Astronomy
Generation of Nonlinear Acoustic Shockwaves Using a Time Reversal Process
The goal of this work is to create a blast wave sound source without using explosives. Time reversal (TR) signal processing is able to create a high amplitude acoustic focus in reverberant environments. With a single acoustic source, the TR process creates additional virtual sources by timing the reflections of energy from room walls to arrive at an intended focus position at the same time as the direct sound arrives from the actual acoustic source. When multiple acoustic sources are used, a set of virtual sources is created for each through the TR process and the amplitude of the focusing is compounded. Eight loudspeaker horns are setup in a reverberation chamber to generate the highest possible focus of acoustic energy. When repeated in incremental increasing input intensities, anomalies in the focused energy become apparent. These anomalies stem from nonlinear propagation of the waves as they constructively interfere at the focus position. This study explores the physical source of these nonlinear anomalies through multiple types of measurements.