Effects of spatial cue dynamics on the perceptual organization of sound

Henri Pöntynen

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

The auditory system is constantly analyzing the mixture of sounds arriving at the ears to form mental representations of the sound sources present in the environment - a process known as the perceptual organization of sound. This process relies on heuristics derived from the statistical properties of sounds heard in natural environments, including those of their perceived directional properties. Auditory percepts have a salient spatial dimension that reveals the locations of sound sources with remarkable accuracy despite the fact that the sensory receptors of the auditory organs are not sensitive to sound direction. Rather, directional hearing is an inherently computational process wherein implicit spatial cues are extracted neurally from the acoustic waves arriving at the ears. While the vast majority of spatial hearing research has focused on the perception of individual point-like sources under conditions where both the listener and the source remain static, natural listening scenarios are rarely this simplistic. Instead, when sounds are heard outside of laboratory conditions, the spatial cues available to listeners are constantly changing due to the combination of listener and source movements as well as acoustic interference between concurrently active sound sources. Yet, the role of spatial cue dynamics in the perceptual organization of sound remains an unexplored topic in many fields of auditory research. The experiments included in this thesis address various auditory phenomena associated with dynamically varying spatial cues. Publications I, II, and IV document behavioral studies where the perceptual effects of spatial cue dynamics arising from the combination of listener and source motion (PI), listener motion alone (PII), or from acoustic-domain interference of multiple concurrently active sources (PIV) were assessed. The results of these studies show that cue dynamics can both enhance and degrade the accuracy of auditory perception. Publication III documents a neuroscientific experiment where electroencephalography was used to assess the cortical responses evoked by random-chord stereograms — a type of auditory stimulus capable of evoking binaurally driven auditory illusions. The results show that these stimuli evoke robust cortical responses as indicated by various time-, frequency- and time-frequency-domain measures. Random-chord stereograms could therefore potentially provide a flexible research tool for neuroscientific experiments seeking to isolate binaurally driven processes in the perceptual organization of sound. Overall, the results provide new insights into the role of spatial cue dynamics in auditory perceptual organization. The results are informative for the design of novel audio processing algorithms for binaural audio devices as well as for improving the ecological validity of auditory experiments across disciplines.
Translated title of the contributionEffects of spatial cue dynamics on the perceptual organization of sound
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Pulkki, Ville, Supervising Professor
  • Salminen, Nelli, Thesis Advisor
Publisher
Print ISBNs978-952-64-0423-3
Electronic ISBNs978-952-64-0424-0
Publication statusPublished - 2021
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • psychoacoustics
  • spatial hearing
  • auditory scene analysis
  • auditory neuroscience

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