Roy Patterson - Brain imaging of pitch perception and the problem of cochlear distortion

Fri, 05/04/2012 - 1:15pm - 2:30pm
CCRMA Seminar Room
Event Type: 
Hearing Seminar
Ahh, pitch.  One of our favorite topics at the Hearing Seminar.  It seems like a simple problem... we know what pitch is, right? But it's not so simple, and modeling pitch still reflects one of the biggest controversies in auditory modeling.  Just how is it that we assign a pitch to a sound? The spectral and the temporal people have been fighting for years.

At this week's CCRMA Hearing Seminar, I'm pleased to say that Roy Patterson will be here to talk about brain imaging work that he has done to help answer this question.  One of the things that makes pitch perception so wonderful is that we can perceive a pitch, even when there is no spectral content at that frequency.  This is the missing fundamental or residue pitch problem. But things get more complicated when the auditory system distorts the signal. This produces distortion products, and Roy has a new way to measure their influence.

    Who:    Roy Patterson
    Why:     Pitch is so fundamental to our understanding of audition
    What:    Brain imaging of pitch perception and the problem of cochlear distortion
    When:    Friday May 4 at 1:15PM
    Where:    CCRMA Seminar Room, Top Floor of the Knoll

Bring your favorite pitch detector to CCRMA, and Roy will bring the pictures! This lecture is also sponsored by the Shenson family, and I appreciate their support of this and a number of music-department activities.  Thank you.

- Malcolm

Brain imaging of pitch perception and the problem of cochlear distortion
Roy D. Patterson

Recently, brain imagers have been searching for pitch processing activity in auditory cortex. They typically use periodic sounds which do not have energy at the fundamental in order to ensure that they are dealing with the mode of pitch extraction associated with music and speech. There remains the possibility, however, that nonlinearities in cochlear processing generate a distortion tone on the basilar membrane at the fundamental of the sound, and that the brain activity reflects detection of a cochlear frequency rather than a pitch perception. This talk reviews the brain imaging problem and describes the role of cochlear distortion in pitch perception with the aid of an auditory model (Lyon et al.  2011) that can simulate the cochlear distortion produced by complex sounds.

Roy Patterson received a B.A degree from the University of Toronto in 1967, and a Ph D. from the University of California in 1971, on the perception of residue pitch. In parallel he developed a method for measuring the shape of the auditory filter. On graduating he went to work at the Defence and Civil Institute of Environmental Medicine back in Toronto where he refined the method of filter shape measurement.

From 1975-1995, he was a research scientist for the UK Medical Research Council, at their Applied Psychology Unit (15 Chaucer Road, Cambridge), focusing on the measurement of frequency resolution in the human auditory system, and computational models of the auditory perception. He also designed and helped implement auditory warning systems for civil and military aircraft, railway maintenance equipment, the operating theatres and intensive care wards of hospitals, and most recently, fire stations of the London Fire Brigade.

Since 1996, he has been the head of the Centre for the Neural Basis of Hearing in the Physiology Department of the University of Cambridge, UK. The focus of his current research is an ‘Auditory Image Model’ of auditory perception and how it can be used to 1) normalize communication sounds for glottal pulse rate and vocal tract length, and 2) produce a size-invariant representation of the message in communication sounds at the syllable level.

Dr Patterson is a Fellow of the Acoustical Society of America and has published over 100 articles in JASA and other international journals.

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