Acoustical Society of America
R. Bruce Lindsay Award - 1989

Mark F. Hamilton

Some of us who work in acoustics got here by long planned design. For others an early love of music developed into a scientific or engineering curiosity about sound. Still others simply fell into acoustics by historical accident. Mark F. Hamilton is in the last category. Seeking an elective course as an electrical engineering senior at Columbia in the fall of 1977, he decided to take something called "Sound and Vibration," taught by an instructor he had never heard of, Cyril Harris (1985 recipient of the Society's Gold Medal). The chance encounter with Cyril landed Mark onto Bruce Lindsay's wheel of acoustics* somewhere near the center.

Encouraged by Cyril to go to Penn State for graduate work in acoustics, Mark began during the summer of 1978. Near the end of his master's research (a topic in cavitation) Mark took another course "blind." This time the result was to determine the field he would follow to the present day. The course was Francis H. Fenlon's "Nonlinear Acoustics." In 1980 Mark became Frank's Ph.D. student and began research on the effect of dispersion on parametric arrays. The very warm and fruitful relationship that developed between student and professor was cut short by Frank's tragic death halfway through the research, in June 1981. However, the influence Frank had on Mark extended far beyond the short period they knew each other. One of the last goals on the list of topics Frank set forth for Mark (not necessarily to be accomplished in the Ph.D. work) was scattering of sound by sound. Substantial success toward this goal has recently been achieved by Mark's first Ph.D. student, Corinne Darvennes.

After Frank's death, Mark came to Applied Research Laboratories, The University of Texas at Austin (ARL:UT), to finish his doctoral research under the guidance of one of us (DTB). He received his degree from Penn State in 1983, and the Acoustical Society awarded him its F. V. Hunt Postdoctoral Fellowship, which he spent at the University of Bergen, in Norway, with Sigve and Jacqueline Tjøtta. During the year Mark found time for a few nontechnical activities, such as meeting Karla Karpen, another displaced American, who became his wife in 1985. He also sampled cross country skiing. Sigve took him on an all day jaunt that quickly had Mark appreciating Sigve's physical abilities as well as his technical ones. Mark might have communicated his admiration for Sigve's skill had Sigve not been just a speck in the distance. Mark returned to UT Austin in 1984 as a research fellow at ARL:UT and a year later joined the faculty as an assistant professor in the Department of Mechanical Engineering. His promotion to Associate Professor will take effect in September this year.

Mark is receiving the Lindsay Award for research in nonlinear acoustics. As noted above, it all began with his doctoral work on parametric arrays in dispersive fluids. In his Hunt Fellowship year with the Tjøttas in Norway, Mark leaned a great deal more about intense directional radiation. He became involved in the development of a computer program that calculates the field of high intensity sound beams. The model includes the combined effects of nonlinearity, diffraction, and dissipation. Subsequent improvements, including the capacity to handle focusing, have been made by Mark in collaboration with the Tjøttas and their students. The model is a major achievement and is expected to have a significant impact on scientific and engineering applications of nonlinear acoustics. The applications Mark and his students have already explored include distortion of focused beams (very important for the acoustical microscope and medical ultrasonic imaging), use of parametric interaction to measure directivity of ship noise, and that ancient but venerable chestnut scattering of sound by sound. He has also applied his knowledge of two-dimensional nonlinear interaction to waveguide problems, namely, interaction of periodic waves in two different waveguide modes, and noncollinear interaction of noise with a tone.

Mark is a talented communicator and an outstanding teacher. His lectures, like his ASA papers, are models of logical, well-organized presentation. His students certainly appreciate him. In his very first course at UT Austin, Noise and Vibration Control, the students closed the last day of class with resounding applause. He admits being taken aback by the display, thinking at first that the students were merely expressing relief that the course was over.

Mark's efforts have earned him a great deal of recognition. He was named an NSF Presidential Young Investigator in 1986, received the ASME Pi Tau Sigma Gold Medal in 1988, and won a Packard Fellowship in 1988. He has also been very active in the Acoustical Society. He has served on the Technical Committees on Physical Acoustics and Engineering Acoustics, and is currently Chairman of the Committee on Education in Acoustics.

Moreover, his reputation goes well beyond the national level. He is well known to the international community in nonlinear acoustics through written publications and papers given at international conferences. His work was so well received at Novosibirsk in 1987 that he was invited to return to the USSR last summer to visit research laboratories and give lectures on nonlinear acoustics. It was a thrill for him to encounter in person many Soviet scientists who work in nonlinear acoustics. Of particular interest was Evgeny Zabolotskaya, whose pioneering work on interaction of diffraction and nonlinear distortion in beams (she is the "Z" in the famous KZK equation) was the starting point for his own research.

Recognized both nationally and internationally to an extent very unusual for so young a scientist-engineer, Mark is the ideal person to receive the R. Bruce Lindsay Award.

DAVID T. BLACKSTOCK

ILENE J. BUSCH-VISHNIAC

*Lindsay's diagram [J. Acoust. Soc. Am. 36, 22–42 (1964)] showing the relation of fundamental acoustics (in the center) to applied fields of acoustics, and in turn their juxtaposition to broad areas of knowledge, both technical and nontechnical.