Teaching underwater acoustics and sonar during the COVID pandemic

Abstract

USNA’s Underwater Acoustics and Sonar (SP411) course, taught in a studio classroom, can seat 36 students with 5 experimental/computer workstations on each side of the classroom. This non-laboratory course relies on hands-on demos and in-class mini-laboratory experiences bringing theoretical concepts and experimental aspects of sound propagation and detection theory to life. Experiments include: (a) sound speed versus temperature in water, (b) beam pattern functions versus angle for multi-element arrays, (c) Fourier analysis of periodic waveforms including rectangular pulses, and (d) square law detection of signals plus noise—generating receiving operating characteristic ROC curves. Computer visualizations using Mathematica included phasor addition of signals, N-element array superposition for directivity analysis and a user friendly ray tracing program implementing any sound speed versus depth profile. On 20 March, 2020, the USNA entered the pandemic era by requiring remote learning for all 4100 midshipman, commencing shortly after spring break. Remote learning in SP411 was asynchronous, devoid of lectures, including handouts and videos of wave effects and worked examples. Mathematica visualizations replaced experiments and extra instruction (in different time zones) was always available. Co-author LEB’s photoacoustic imaging experiments, done remotely, used homemade electronics (pulsed LED driver and low-noise amplifiers)—keeping future midshipmen research going.