Henry Ellis Bass

Acoustical Society of America

Biennial Award

1978

Henry Ellis Bass

Henry Ellis Bass was born in Tulsa, Oklahoma, on 31 August 1943. He received the B.S. in 1965 and the Ph.D in 1971 in physics from Oklahoma State University. He is currently Associate Professor of Physics at the University of Mississippi, and holds the rank of major in the U.S. Army Reserve assigned to the Office of the Deputy Chief of Staff for Research, Development and Acquisition.

Hank's brilliance and his insatiable appetite for challenge brought him distinction even before he graduated from McLain High School in Tulsa. Although he was working more than forty hours a week to support himself and his growing family, his academic record won him college scholarships from Sears and General Motors Companies. His first encounter with acoustics was in Professor Tom Winter's laboratory at O.S.U. In his senior year he helped to develop a capacitance microphone using a ceramic diaphram for Winter's high temperature sound absorption measurements. After a two-year tour of active duty with the Signal Corp, he returned to O.S.U. to enter graduate school and to continue his work with Winter. As a graduate student, he briefly investigated acoustical holography before setting on an acoustical study of relaxation in gases. His dissertation research was an ambitious investigation of rotational relaxation as a function of temperature in a series of polar polyatomic gases.

Hank attended the first Gordon Conference on energy transfer a year before he received his Ph.D. degree. At this meeting he met Hans Bauer and Don Thompson, both of whom he later influenced to spend a year at the University of Mississippi and with whom he has collaborated on a number of papers. During his first year at Ole Miss, his interest centered on multiquantum processes in vibrational relaxation. Working with Bauer the following year, he extended Bauer's matrix formalism to vibrational relaxation in multicomponent mixtures.

Perhaps Hank's greatest forte is his ability to apply theory to the explanation of physical phenomena. He immediately recognized in Bauer's matrix formalism a powerful tool of wide applicability. Not only did he use his theory to solve the long-puzzling problem of the frequency and humidity dependence of sound absorption in the atmosphere (a work which has since led to a new sound absorption standard), but he also used it to obtain transition rates from laser fluorescence and from laser–laser double resonance experiments, to explain thermal blooming of a high-power CO2 laser beam in the atmosphere and to predict the amplification of sound upon passing through a gas with a nonequilibrium distribution of excited states (a phenomena he likes to call SACER).

The study of sound absorption in air has led him out of doors to an investigation of such diverse phenomena as the filtering effect of the atmosphere upon the spectrum of thunder, sound emissions from tornadoes, the absorption of sound propagated over various types of ground cover, the coupling of airborne sound into the earth, and, most recently, the effect of relaxation on the rise time of shock waves.

In the laboratory, he has the rare touch for making equipment respond and in recognizing that which is significant and that which is insignificant in data. He is equally as brilliant in plowing through mountains of published data to discover the secret hidden pattern or in carrying out an involved numerical analysis of a theoretical problem using the computer. Usually, he has one or more projects of all three types going at the same time. In the latter category, he has made significant contributions in predicting transition rates from classical trajectory calculations. As a visiting staff member at Los Alamos Scientific Laboratory, he and Don Thompson have been the first to use this method to calculate energy transfer rates in diatom–diatom molecular collisions.

Productive as he has been, research is not all for Hank. An innovative and stimulating teacher, he succeeds in challenging and exciting his students, whether giving a lecture to a large class in beginning astronomy, developing a self-paced course using the computer, or teaching a graduate course in statistical mechanics. Other interests have involved him in such diverse activities as private consulting and a proposal for a solar-heated home.

The father of three talented children—Belinda, 16 Christine, 14, and Henry, Jr. 10; Hank is a kind and generous person with a sincere regard for the worth of others. He listens when others talk and brings out their best effort whether on the tennis court or in the laboratory. He is a worthy addition to the distinguished list of Biennial Award winners.

JOSEPH E. PIERCY

F. DOUGLAS SHIELDS