Shihab Shamma, University of Maryland and Acoustical Society of America will give the UPF-DTIC Research seminar Friday, October 24, 2014, 11:00 am , 55.410
Host: Paul Verschure (SPECS)
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Title: Cortical Mechanisms to Navigate Complex Auditory Scenes
Humans and other animals can attend to one of multiple sounds, and follow it selectively over time. The neural underpinnings of this perceptual feat are the object of extensive investigations. Some studies have concluded that sounds are heard as separate streams when they originate from diverse locations or if they are so different as to activate well-separated populations of central auditory neurons, and that this process is largely pre-attentive.In this lecture, I will review the fundamentals of sound representation in the auditory cortex, including the rapid adaptive processes that occur and the transformations from representation to meaning in the auditory cortical fields up to the prefrontal cortex. I will then explain how "stream formation" or source segregation depends primarily on temporal coherence between responses that encode various features of a sound source. I shall also discuss algorithms for implementing this process that are inspired by auditory cortical mechanisms. Finally, I will discuss why attention is necessary for this process and how it induces this perceptual transformation when directed towards a particular feature of a sound (e.g., pitch). I will also argue that only through attention do all temporally coherent features of a source (e.g., timbre and location) become bound together as a stream that is segregated from the incoherent features of other sources.
Dr. Shamma's research deals with the question of how the acoustic signal is represented at various levels of the mammalian auditory system. The research spans a wide range of disciplines and techniques, ranging from theoretical models of auditory processing the early and central auditory stages, to neurophysiological investigations of the auditory cortex, to psychoacoustical experiments of human perception of acoustic spectral profiles. These studies complement each other in that theoretical models are directly based on experimental data, and in turn the models motivates the experimental paradigms and analysis.