Defence of doctoral thesis in the field of Acoustics and Audio Signal Processing, M.Sc. Henri Pöntynen

The sense of hearing enables spatial awareness and identification of objects of interest in one’s surroundings even when sources of sound are not directly visible. The auditory system achieves this feat by exploiting implicit acoustic cues embedded into the sound waves arriving to the listener’s ears. The sound wave features that enable directional hearing are referred to as spatial cues. While spatial cues have received a lot of attention in auditory research, only a handful of studies have explicitly investigated the effects of their dynamic variations on different aspects of auditory perception. Understanding these effects is important, since spatial cue dynamics are almost always present in real-life listening scenarios, where listeners and sound sources are in motion.

This work investigated the effects of dynamically varying spatial cues on the formation of auditory percepts in normal-hearing humans. A series of psychoacoustic experiments and one electrophysiological study were conducted that sought to address open questions related to the role of spatial cue dynamics in auditory perception. Overall, the results of the behavioral experiments show that spatial cue dynamics, especially those arising from listener movements, contribute significantly to spatial hearing, as well as to the more fundamental perceptual process of sound source identification. Similarly, the results of the electrophysiological study show that spatial cue dynamics can affect the on-going neural activity of the auditory brain in manner that is detectable in electroencephalographic measurements.

The work provides new information about how auditory percepts are formed in behaviorally relevant listening scenarios involving moving listeners and sound sources. As such, the results contribute towards understanding how the hearing system processes the complex acoustic scenes encountered in everyday life, where sounds and listeners tend to be in motion rather than stationary. The results find practical applications in the development of sound processing algorithms for binaural hearing devices and contribute to the development of novel stimulation paradigms for auditory neuroscience experiments specifically interested in directional hearing.

Opponent: Associate Professor Ewan Macpherson, Western University, Canada

Custos: Professor Ville Pulkki, Aalto University School of Electrical Engineering, Department of Signal Processing and Acoustics

The defence will ne organised via remote technology (Zoom). Link to the defence.

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The doctoral thesis will be publicly displayed 10 days before the defence in the Aaltodoc publication archive of Aalto University.