Acoustical Society of America
R. Bruce Lindsay Award - 2001

Andrew J. Oxenham

Andrew Oxenham has an English father and a German mother but was born in the USA, which no doubt is linked to the fact that he speaks German, English and American fluently. He became an excellent piano player while quite young, as his parents told him "you can stay up late if you practice; otherwise, you have to go to bed. His interest in music led him to take a bachelor degree in Music and Sound Recording (Tonmeister) at the University of Surrey, England, achieving First Class Honors (a rare event for that subject). He then applied to Cambridge University to do a further degree in engineering. By pure coincidence, I happened to be on the committee at Wolfson College, Cambridge, that interviewed him for admission. After a few minutes of interview time, I realized that he was an exceptional person, and suggested to him that he should forget about doing the engineering course, and instead do a Ph.D. under my supervision. After a brief visit to my laboratory, he agreed. I don't think that he regretted this decision.

His Ph.D. thesis was an outstanding piece of work, which led to several papers in The Journal of the Acoustical Society of America. He showed quantitatively how the combined effects of forward and backward masking could be modeled using the concept of a sliding temporal integrator preceded by a compressive nonlinearity and he showed how the "shape" of the temporal integrator could be derived. In addition, he showed how reduced compression associated with cochlear hearing loss could be used to account for the way that forward and backward masking combine in hearing-impaired listeners. His thesis work also led to new insights into the "overshoot effect," and how that effect was related to Weber's law, and departures from it.

Andy finished his Ph.D. in a period of less than three years, an unusual achievement. His external examiner was Dr. Christopher Plack. It must also be unusual that, during the Ph.D. oral examination, Andy and Chris together devised the initial plans for a highly productive collaboration and series of experiments, which are described below. Many people were sorry when Andy left Cambridge, not least because we had great difficulty replacing him as the piano player in the Wolfson College Jazz Band and as accompanist to the Wolfson College Choir.

After finishing his Ph.D., he went to the Institute for Perception Research (IPO) in Eindhoven, as a recipient of a Prize Fellowship from the Wellcome Trust. While there, he conducted several novel experiments, mainly concerned with the measurement of basilar membrane compression and its functional implications. His work on this topic, conducted in collaboration with Chris Plack, led to a behavioral method for estimating basilar-membrane nonlinearity in humans. This paper has had a very substantial impact on the field and is extensively cited. In connection with this, he also showed how reduced temporal integration in hearing-impaired listeners could be accounted for (partly) in terms of reduced peripheral compression. He also worked on the detection of brief increments and decrements in level, and has described a new approach to the analysis and interpretation of the results.

While at IPO, Andy supervised a research project concerned with the perceptual organization of sequences of sounds. The original idea for the project came from him. The experiments showed clearly for the first time that sequential grouping could be based on periodicity information, in the absence of any "place" (spectral based) information. This work has important implications, as the results contradict current models of sequential grouping processes.

Following two years at the IPO, Andy moved to work in the laboratory of Dr. Mary Florentine and Dr. Søren Buus at Northeastern University. While there, he conducted important work on intensity discrimination, which clarifies the role of peripheral and central noise in different forms of intensity-discrimination task. He also performed ingenious experiments on gap detection, showing that peripheral coding noise is dominant in determining gap-detection thresholds when the two markers (on either side of the gap) differ along any physical dimension. Higher-order neural coding mechanisms based on fundamental frequency and spatial location seem to play a smaller role and no role, respectively. These results led to an interpretation very different from that of earlier researchers. In his most recent work, Any has examined temporal integration effects in forward masking. The results suggest that forward masking is primarily caused by a form of temporal integration (persistence) rather than by adaptation, as has commonly been assumed. Andy is currently based in the Research Laboratory of Electronics at the Massachusetts Institute of Technology, funded by his own research grants, where he makes an active contribution to the auditory community in the Boston area.

I have emphasized Andy's achievements in research, but I should also mention that he is a very effective teacher and communicator and that, as a member of the Technical Committee on Psychological and Physiological Acoustics, he plays an active role in the affairs of the Society. He has been an invited speaker, and is particularly valued as a reviewer. He is also a really "nice guy." He is never pushy, but can be quietly insistent when he knows that he is right. He is always ready to lend a helping hand. For example, while in my laboratory he often helped other research students to solve programming problems and problems in operating equipment. He is a loving husband (to Sylvia) and his achievements are all the more remarkable given that he is the father of two young children (Julien and Alena).

I am delighted to congratulate him on behalf of his many friends and colleagues on being awarded the R. Bruce Lindsay Award.

BRIAN C. J. MOORE