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TECHNICAL COMMITTEE REPORT
Andrew J. Oxenham
Postal:
Department of Psychology University of Minnesota Twin Cities 75 East River Parkway Minneapolis, Minnesota 55455 USA
Email:
oxenham@umn.edu
Physchological and Physiological Acoustics
Members of the Psychological and Physiological Acoustics Technical Committee have varied interests related to all aspects of hearing.
The Technical Committee (TC) on Psychological and Physiological Acoustics (P&P) consists of scientists, clinicians, and engineers whose interests converge around the topic of hearing. Committee members in academia come from a wide variety of departments and disciplines, including biology, biomedical engineering, communication disorders, electrical engineering, neuroscience, otolaryngology, physics, psychology, and speech-language-hearing sciences. This broad range of departments highlights the multidisciplinary nature of the field. Of course, not all members work in academic settings, and we have strong industry representation, primarily from people working in the area of medical devices such as hearing aids and cochlear implants.
Progress in the field is being made on several fronts, and there remain many ex- citing mysteries to solve regarding how the workings of the ear and brain result in our perception of the acoustic environment around us. Since Cherry’s (1953) famous paper on the “cocktail party problem,” published over 60 years ago in The Journal of the Acoustical Society of America (JASA), much effort has been devoted to answering the question of how we are able to perceptually segregate and attend to one or more sounds in the presence of many other competing sounds, noise, and reverberation. In most cases, the problem is mathematically “ill posed”: there is no unique solution to how the single pressure waveform reaching the eardrum should be decomposed into the multiple waveforms that were generated by the different sound sources in the environment. Instead, we must rely on previous in- formation or “priors” to correctly parse the incoming signal into “auditory objects” or “streams.” These priors may be learned from our previous exposure to sounds or they may be “hardwired” into our auditory system, representing information ac- cumulated over evolutionary time and instantiated in the anatomy and physiology of the ear and auditory neural pathways.
Members of the P&P TC are studying every part of these auditory pathways from the eardrum and middle ear to the primary and secondary auditory cortex in the brain’s temporal lobes and at every level of investigation from the mechanics and structure of single hair cells in the cochlea to the whole system approach required when studying perception through behavior in humans and other animals.
Starting with the ear canal, the tympanic membrane, and the middle ear (home to the smallest bones in the human body and the place where airborne sound is transduced into mechanical vibrations of those bones), new insights continue to be made into these first and crucial steps of the transduction process using ever- improving measurement techniques including laser interferometry and digital ho- lographic techniques (e.g., Khaleghi et al., 2016). The cochlea of the inner ear is where the mechanical vibrations produced by sound are transduced into the neural spiking code of the brain. Here, too, new discoveries in physiology, molecular biol-
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