Nonlinear interactions in the 1970s: Tribute to the work of Robert T. Beyer

Abstract

Professor Beyer was our thesis advisor and supported, motivated, and directed both T.K.S’s and M.S.K’s Ph.D. research in the area of nonlinear underwater acoustics at Brown University. T.K.S performed experiments in an effort to measure the nonlinear interaction of sound with noise, while M.K.S did experiments involving the scattering of sound by sound in the presence of turbulence. Along the way T.K.S designed and built a complex intensity meter and measured the growth of the nonlinearly generated sidebands with propagation distance, while M.S.K designed and built a hot-film anemometer and measured the angular dependence of the spectral broadened sum frequency versus angle. We also learned ultrasonics and nonlinear acoustics from our mentor, who wove in the works of Rayleigh, Lighthill, and Westervelt along the way. Beyer also gave us a passion for the history that goes beyond the science. In the spirit of ‘‘once a graduate student, always a graduate student,’’ and ‘‘don’t just stand there go write a thesis,’’ in our tribute to Beyer we will try to tell the ‘‘vintage story’’ that is spun around Professor Beyer the scientist, author, and teacher who established B/A, and made the earliest measurements on the parametric array.