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Binaural Beats, Brain Rhythms and Binaural Hearing - Bernhard Ross

October 10, 2014 - 3:00pm to 4:00pm
CCRMA Classroom - Knoll Room 217
Binaural Beats, Brain Rhythms and Binaural Hearing

Binaural beats are an auditory sensation when two different frequencies are presented to the two ears. The individual percepts combine in the central auditory cortex and the results are beating sounds, or roughness. This week’s speaker, Bernhard Ross from the University of Toronto, has studied binaural beats with MEG recordings. This is the perfect modality for these tests since the recordings can be synchronized to the beats.

Bernhard Ross, Ph.D. (Rotman Research Institute & Department of Medical Biophysics, University of Toronto)

Bernhard Ross is a Senior Scientist and Director of MEG laboratory at the Rotman Research Institute and Associate Professor in the Department of Medical Biophysics at the University of Toronto. He holds degress in Electrical Engineering and PhD in Medical Science. His main research interest lies on a question how neurophysiological signals in MEG can inform us about the nature of complex brain mechanisms that afford us to understand the world from sensory information such as hearing and touch. He was involved in the installation of one of the first generation single channel magnetoencephalography (MEG) devices and the development of custom acquisition software and hardware in 1984 in University of M?nster. He published over 100 articles including his contribution to pioneering work in neuromagnetic auditory research and some of the first seminal studies in brain plasticity in musicians. He is a founding member of the Canadian MEG Consortium, which connects all MEG laboratories across Canada to overlook shared platform development for MEG analysis tools and management of research exchanges.  Abstract: Two tones with slightly different frequencies, presented to both ears, interact in the central auditory brain and induce the sensation of a beating sound. At low difference frequencies, we perceive a single sound, which is moving across the head between the left and right ears. The percept changes to loudness fluctuation, roughness, and pitch with increasing beat rate. To examine the neural representations underlying these different perceptions, we recorded neuromagnetic cortical responses while participants listened to binaural beats at continuously varying rate between 3 Hz and 60 Hz. Binaural beat responses were analyzed as neuromagnetic oscillations following the trajectory of the stimulus rate. Responses showed specific frequency characteristics and polarity changes between the left and right auditory cortices. We discuss that binaural processing at the cortical level occurs with same temporal acuity as monaural processing whereas the identification of sound l! ocation requires further interpretation and is limited by the rate of object representations.   Hearing Seminar host: Malcolm Slaney (CCRMA consulting professor & Microsoft) & Takako Fujioka (Assistant Professor at CCRMA Neuromusic lab)