Acoustical Society of America
Gold Medal Award - 2001

Herman Medwin

HERMAN MEDWIN, past President of the Acoustical Society of America and founder of the Acoustical Society's Acoustical Oceanography Technical Committee, was born in Springfield, Massachusetts. He spent his early years in Holyoke, Massachusetts, where at the age of 10 he began what became his lifelong avocation of playing the violin. He subsequently attended Worcester Polytechnic Institute where he received his B.S. in Physics (1941). Hank recalls with chagrin being at the bottom of nearly every class except the one using Morse's textbook, Vibration and Sound, in which he ranked first. Following graduation he worked in Pratt and Whitney's engine test and inspection group, and while there he dated a girl from Smith College. Although Smith was exclusively a women's college, Hank demonstrated his pioneering spirit by taking advantage of the school's wartime flexibility to sign up as its first male student. From such beginnings great acoustical scientists are made!

Shortly after joining the United States Army Air Force, in 1944 he was transferred to the United Kingdom as a Weather Observer. There he met Eileen Huber, from Vienna, Austria, who was serving in the First Allied Platoon of the British Army. They were married six months later. Upon their return to the United State, Hank applied for graduate studies in California. When Cal Tech learned of his interest in acoustics, their immediate advice was: "Go to UCLA." At the time UCLA, the University of California at Los Angeles, had a truly stellar cast of acousticians. In addition to his supervisor, Izzy Rudnick, Hank's doctoral committee included Bob Leonard, Vern Knudsen, Carl Eckart and Leo Delsasso. For his thesis topic he mixed theoretical and experimental approaches to elucidate the sources of acoustic streaming, first described by Lord Rayleigh and later studied by Carl Eckart. Hank modified the theory for the actual profile of the acoustic field and measured it experimentally in air. His results were quantitatively more accurate than Leonard Liebermann's classic work on acoustical streaming in liquids, which assumed a uniform acoustic field over the transducer aperture. Concurrent with his graduate work at UCLA, he was a full time instructor in Physics at Los Angeles City College. He also found time to pursue his lifelong musical interests as a violinist with the UCLA Symphony Orchestra and the Los Angeles Civic Orchestra..

Following a postdoctoral year at UCLA Hank spent a year at Bolt, Beranek and Newman working on noise control, a topic to which he returned much later. In 1955 he accepted a position at the Naval Postgraduate School of Monterey, California and began a long and extraordinarily productive career as teacher, mentor and scientist. Following his doctoral research in nonlinear acoustics, Hank's early studies were in the growth and decay of shock waves. Maybe it was the proximity of the sea to Monterey, or perhaps the naval focus at the School that soon prompted him to ask what research he could do involving the ocean. In the 1960s he carried out the first acoustical measurements of microbubbles in the laboratory and ocean using in situbackscatter, excess attenuation and dispersion. He also blended innovative theoretical approaches and clever, inexpensive laboratory studies to examine sound scattering from a rough surface. He continued to pursue these interests during the 1970s, expanding his studies to include the scattering of sound from a randomly rough surface. He also pursued an understanding of the effects of temperature microstructure and bubble density fluctuations in the upper ocean on acoustical propagation. As a result of his interactions with Ivan Tolstoy during Tolstoy's visiting professorship at the Naval Postgraduate School, Hank was led to reinterpret and greatly clarify the theory of scattering from a rough surface. With his students he verified the theory with numerous experimental tests over a wide range of geometries. Extending the original formulation for semi-infinite wedge planes to finite width facets, which he confirmed experimentally, Hank applied the results to shadowing by a highway noise barrier, to shadowing and diffraction around a seamount (an underwater mountain), to the rough ocean surface and ice leads and, more recently, to sound scatter in an auditorium. In collaboration with Tolstoy, he experimentally verified the existence of a scattered acoustic boundary wave generated by grazing incidence at a slightly rough surface. In the 1990s he provided the first experimental attribution to the Knudsen sea noise spectrum to bubbles produced by breaking waves ane explored the impact and bubble noise produced by rainfall.

Professor Medwin's teaching responsibilities at the Naval Postgraduate School placed him in close contact with numerous young naval officers whose goal was to gain some research experience in a Master's degree before continuing with their military careers. This favored his pursuit of sharply defined projects that could be completed in a short period of time with minimal risk and cost. His students came from many nations and they gained immensely from their brief, but intensive, interaction with Hank. His lengthy list of publications, in the Journal of the Acoustical Society of America and in the Journal of Geophysical Research illustrates an unusually elegant approach to experimental acoustics. He has produced a series of insightful contributions on topics as diverse as the noise produced by falling rain drops, scattering from rough surfaces, the development and validation of methods for measuring the vertical distribution and sizes of bubbles just under the sea surface, and the acoustics of auditoriums. Bubbles near the sea surface impact such critical issues as the exchange of gases between the ocean and the atmosphere, modify acoustic scattering from the surface of the sea, and by absorption and scattering can change the spectrum of undersea ambient noise generated by breaking waves. Although Hank acquired important and valuable insights from field measurements in the ocean, much of his work was carried out in the laboratory, in part because the motion of rolling, heaving ships doesn't always agree with him. The ability to replicate his experiments in a laboratory environment also allowed him to carry out detailed comparisons between theory and observation, as well as to develop and verify inversion methods that lie at the heart of acoustical oceanography.

His long and fruitful collaboration with Clarence S. Clay, together with the experience gained from teaching and graduate student supervision, served as a basis for the textbook Clay & Medwin, Acoustical Oceanography (1977). This was an extraordinarily successful book with many printings and, although intended as an elementary text for students, became a helpful source of information for scientists that were transitioning into the field of applied acoustics, especially from oceanography. Their more recent publication: Medwin and Clay, Fundamentals of Acoustical Oceanography (1977), reflected a shift in emphasis towards the growing interest in using acoustical methods to learn more about the ocean.

In 1980 Hank became Emeritus Professor at the Naval Postgraduate School. Upon his ``retirement' he founded Ocean Acoustics Associates, a small research company. He has continued to pursue an active scientific career as an author and consults on architectural acoustics and noise control issues in the Monterey Peninsula area. He is also often active participant at seminars at the Oceanography Department of the Naval Postgraduate School, the Monterey Bay Aquarium Research Institute, the Moss Landing Marine Laboratory and the Earth Sciences Department at California State University, Monterey Bay. Visiting scientist appointments have taken Hank and Eileen to London, England; the Hudson Laboratories of Columbia University in New York; Sydney, Australia; La Spezia, Italy; Yokosuka, Japan; Woods Hole, Massachusetts and various universities in China.

Hank's special contributions have been recognized in many ways, including an honorary doctorate from Worcester Polytechnic Institute and the Society's prestigious Silver Medal in Acoustical Oceanography. In addition to his terms as Vice President (1988) and President (1992) of the Acoustical Society of America, he was the Chair of two Technical Committees (Underwater Acoustics and Acoustical Oceanography), and has served on over a dozen of the Society's administrative committees. One of his most widely appreciated achievements was arranging a special benefit concert for the ASA by the Tokyo String Quartet at the 127th meeting of the Acoustical Society in Cambridge, Massachusetts in 1994. He is especially proud of the part he played in establishing a tradition of having two evening Social Buffets, now standard at Society meetings. These events have been extremely successful in providing time for informal communication among members. As the Acoustical Society's Vice-President and the Chair of the Technical Council, Hank worked assiduously to encourage the Society to take advantage of evolving scientific and technological interests in acoustically related fields. The increased adaptability he strongly advocated allows the Society to remain in closer touch with shifts of emphasis and new applications of acoustics within our changing field, attracting new members with different, yet common interests, and helping to make the Society their professional home.

In 1991 he became Founding Chairman of the Acoustical Oceanography Technical Committee. He tirelessly sought to bring within the Society's fold a growing band of oceanographers who saw the exciting possibilities of acoustical methods. It is very much to Hank's credit that ASA meetings now include special sessions on acoustical oceanography covering everything from fish and plankton acoustics to surf zone studies and ice noise. This transformation has benefitted not only from Hank's scientific dedication and inspiration, but also from his and Eileen's deep personal generosity in funding the Medwin Prize in Acoustical Oceanography. The Acoustical Society's leadership in this emerging collaboration of disciplines owes much to Hank's foresight, enthusiasm, generosity and downright tenacity.

The Society is proud of Hank's contributions and delighted to recognize them with its most distinguished award.

David Farmer
Fred Fisher