Acoustical Society of America
Gold Medal Award - 2002

Tony F. W. Embleton

TONY FREDERICK WALLACE EMBLETON was born in Hornchurch, near London, England on 1 October 1929. After receiving a classical education from Brentwood School, he entered Imperial College in 1947 with a Royal Scholarship. He received his B.Sc. in Honor Physics from the University of London 3 years later. During this time, Tony became acquainted with R.W.B. Stephens and decided to join the newly-formed Acoustics Group in the Physics Department of Imperial College where he received a Ph.D. in physics for his experimental work on finite amplitude waves in 1952. A post-doctoral fellowship awarded by the National Research Council brought him to Ottawa, Canada. Tony was offered a position in the Division of Physics the next year where he remained on staff until his retirement in 1990. In 1953 he married Eileen Blackall. They have a daughter Sheila, who has been a member of the ASA and a granddaughter Anne who has already accompanied Tony and Eileen to an ASA meeting.

Tony's contributions to acoustics have continuously spanned the last five decades. In a long succession of significant contributions to the theory and practice of noise control, he has studied sound generation and radiation, acoustical measurement techniques, noise control methods, and sound propagation outdoors. He rose successively through the scientific grades of Assistant, Associate, Senior and Principal Research Officer and became Section Head in 1985. While working at NRC, Tony also earned a D.Sc. degree from the University of London for his work in noise control.

The intense siren-like noise generated by large suction rolls in the paper industry became a matter of national concern in Canada in the early fifties. In partnership with George Thiessen, he studied the efficiency of linear arrays of point sources with linear and periodic phase variations. In theory and by experiments they were able to show that noise reductions of 12 to 20 dB were readily attainable without reducing the productivity of the machine by substituting quiet tailor-made drilling patterns for the simple but noisy pattern in common use at that time. This spectacularly successful project strongly underlined the value of fundamental research in support of noise control and became a template for Tony's scientific career.

During the sixties he participated in several other noise control projects. In particular, fundamental acoustical principles were applied with considerable success to noise reduction in centrifugal blowers and in work on axial-flow compressors. His involvement with train noise measurement in relation to the use of adjacent land was followed by a field study of the potential attenuation provided by rows of trees for use as noise barriers. Although his measurement showed excess sound attenuation, no firm conclusion about the mechanism was provided. This inconclusive evidence led to inspired laboratory work on the scattering of sound by arrays of cylinders and eventually to two decades of seminal work on outdoor sound propagation. At the same time, Tony also undertook to provide the National Research Council with absolute measurements of sound pressure. He developed a reciprocity system with several notable improvements and his systematic work is the basis for Canada's primary acoustical standards. In the years that followed, George Wong, who currently maintains Canada's primary acoustical standards, brought further improvements by working in collaboration with Tony.

In response to growing concerns in Canada over community noise and an evident need for improved methods for predicting and controlling urban noise levels, Tony renewed earlier interest in sound propagation outdoors. His interest has inspired an impressive series of experimental and theoretical studies of sound propagation. In collaboration with colleagues in the Acoustics Section, seminal contributions were made in the areas of the effect of ground on near-horizontal sound propagation, the measurement of ground impedance, phase and amplitude fluctuations due to turbulence, the special characteristics of moving sources, refraction due to wind and temperature, and barrier attenuation in the presence of the ground. In 1983, at the request of the Department of National Defense, he was appointed Lead Canadian Delegate to NATO Committee AC 243/RGS-11, providing Tony the opportunity to apply his extensive experience in another technical area—interest in sound propagation to this day. He presented ASA Tutorial Lectures on sound propagation in 1993 and 2001.

Tony has authored or co-authored more than 50 archival papers and a number of major technical reports, special articles, and book chapters, including "Sound in Large Rooms" and "Mufflers," published in Beranek's Noise and Vibration Control. With Joe Piercy, he co-authored the chapter "Sound Propagation in Open Air," in the Second Edition of Harris' Handbook of Noise Control. With Joe Piercy and Lou Sutherland he co-authored a review paper on outdoor sound propagation, which is still a major reference work in this field. More recently Tony and George Wong co-edited the AIP Handbook of condenser microphones.

Tony's dedication to the advancement of noise control is matched by his dedication to the broad field of acoustics through national and international leadership. For several years, he served as Member or Chair of Canadian committees concerned with machinery noise and noise in the pulp and paper industry. He was founding Secretary of the Canadian Acoustical Association and founding Editor-in-Chief of Acoustical and Noise Control in Canada, the forerunner of Canadian Acoustics. He currently serves on the Board of International-INCE as Vice President–Long Range Planning.

Tony joined the Acoustical Society of America in 1954 and was elected a Fellow in 1964. The list of ASA Committees and ANSI Working Groups on which he has served as member or Chairman is just too long to enumerate here. Just the main highlights constitute an impressive list. He was Chairman of the Technical Committee on Noise from 1964–67, elected to the Executive Council from 1969–72, Associate Editor of JASA for Noise from 1970–75, Vice-President from 1977–78, President from 1980–81, Chairman of ANSI Standards Committee S1 from 1982–85, ASA Standards Director from 1993–97. He has also served at various times on the Committees on Membership, Medals and Awards, Meetings, Books, Long Range Planning, and I probably missed others. A few years ago he undertook the arduous task of revising the Rules of the Society, thereby ensuring not only that we do the right thing, but that we also do it right.

A specific example of Tony's dedication to the Society deserves to be highlighted. He was Technical Program Chair of the Ottawa meeting in 1968 and General Chair of the Ottawa meeting in 1981 during his year as ASA president. He also assisted John Burgess with the three joint meetings with the Acoustical Society of Japan in Honolulu in 1978, 1988, and 1996 by acting as the Technical Program Chair. Of course, those who have experience in organizing large meetings might say that Tony is a glutton for punishment?

Tony's contributions in the field of acoustics have been recognized on a number of occasions. The ASA awarded him the Biennial Award in 1964 and he received the ASA's Silver Medal in Society of Automotive Engineers in 1974, recipient of the John Wiley Jones Award presented by the Rochester Institute of Technology in 1976, he was elected Member of the US National Academy of Engineering in 1987 and elected as Fellow of the Royal Society of Canada in 1978.

It is therefore most fitting that Tony be honored today with the Gold Medal of the Acoustical Society of America.

Gilles A. Daigle