Acoustical Society of America
R. Bruce Lindsay Award - 1988

Gilles A. Daigle

Gilles A. Daigle is the 26th recipient of what until 1986 was called the Biennial Award. He is the second to receive the award under its new name, the R. Bruce Lindsay Award, and under its new charter by which it is presented every year instead of every 2 years.

Gilles received the Governor General's Gold Medal, awarded to the top graduating student in each Canadian university, in 1975, from the University of Moncton, which is the French-speaking university in the province of New Brunswick. He was headed for a career in nuclear physics when he came to work as a summer student in the Acoustics Section at the National Research Council in Ottawa. Something about dragging cables over acres of flat grassland, asphalt, or concrete on a disused airfield and operating instruments out of the back of a station wagon must have appealed to him because he decided to switch fields. He also switched universities and enrolled at Carleton University in Ottawa so as to be near the Acoustics Laboratory at NRC.

The years from September 1975 to early 1981 were particularly busy for Gilles. He took all the available courses in physics at Carleton University, as well as a few courses in acoustics set up especially for him by arrangement between the university and NRC. He did the experimental and theoretical work for his M.Sc. and Ph.D. theses at NRC and, during this same period, he also taught courses in physics at the Edmundston campus of the University of Moncton. Since 1981, he has worked at NRC, briefly as a Postdoctoral Research Associate, but soon as an Assistant Research Officer and, more recently, as an Associate Research Officer.

In his two theses and in subsequent papers (mainly in JASA and at ASA meetings), Gilles has systematically studied each of the many mechanisms involved in sound propagation outdoors. These include interference between direct waves and those reflected at the ground surface, diffraction over barriers, nonflat ground, and creeping waves along surfaces, scattering by atmospheric turbulence (and, more generally, propagation through inhomogeneous media) and refraction by vertical gradients of wind and temperature. The fact that all ground surfaces have a finite acoustic impedance leads to interesting and complicated phenomena—significant phase changes of waves on reflection, the existence of ground waves, and the interaction of sound waves in air with seismic waves in the ground. Also included in his range of studies are realistic ground surface such as layers of snow over harder ground and propagation across an asphalt to grass interface. In each of these areas, Gilles' contributions to either theoretical understanding, to experimental techniques, or to both, have usually been substantial and sometimes unique. This work is important both socially and economically. Prediction schemes for noise levels around airports, alongside highways, and in other places can now be based on an understanding of wave-propagation principles, and can allow for the difference in sound levels as a consequence of daytime and nighttime atmospheric profiles, and whether the listener is on the ground, in a high-rise building, up a hillside, behind a hill, or across water from the source.

The peer recognition accorded Gilles' work is widespread. His advice and teaching are frequently sought by industrial companies, government organizations, and universities not only in North America, but also in Japan and Western Europe. Recently, he has had two visitors that have come at their own initiative to work with him for a year, one from a French government ministry and the other from a Canadian university. For several years, he has taught short courses for local police forces in the Ottawa area, showing police officers how to use sound level meters, how to choose measuring location intelligently, and how to give sufficient and relevant evidence in court. It is not surprising that several of JASA's associate editors are among his most frequent clients.

Gilles takes an active part in the affairs of the Acoustical Society. He currently serves as the Chairman of the Technical Committee on Physical Acoustics, is a member of the Technical Committee on Noise, and has organized several special sessions at ASA meetings. Recently, he became chairman of ANSI standards Working Group S12-27 "Outdoor measurement of sound pressure level." He has also served as Editor of both Physics in Canada and Canadian Acoustics. Apart from the regular duties of soliciting and reviewing papers, he exercised another of his many talents, as a cartoonist, to illustrate aspects of science that happened to catch his humorous attention.

In 1975, Gilles married Nicole St. Laurent, who is a dietitian, as well as being an excellent cook. Perhaps this explains Gilles' love of good food and wine. An achievement shared by Nicole and Gilles occurred only 2 days before his oral doctoral examination when their daughter Annick was born.

We thank Gilles for his contributions, congratulate him on his successes, and look forward to the many benefits to acoustics that his energy and enthusiasm will produce in future years.

TONY F. W. EMBLETON