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Amplitude Envelope: The Hidden Player in Auditory Gestalt Grouping

Amplitude Envelope: The Hidden Player in Auditory Gestalt Grouping

Name:Fadi, Mansour

School/Affiliation:McMaster University

Co-Authors:Andres E. Elizondo Lopez, Connor Wessel, & Michael Schutz

Virtual or In-person:In-person


Gestalt principles help explain how we group auditory sound events. One piano note, for example, contains multiple frequencies that we perceive as one cohesive sound event. When frequencies start or end at different times, the cohesiveness of a tone breaks leading to the perception of more than one sound. This project examines how we group complex tones with varying amplitude envelopes into one cohesive auditory unit. We synthesized tones with a varied amplitude envelope (percussive) and tones with a sustained amplitude envelope (flat) that had a delayed offset (Experiment 1) and delayed onset (Experiment 2). We also conducted experiment 3 which used sounds from both experiments 1 and 2. The tones that participants heard were complex tones with their 4th and 5th harmonics having either a later offset (experiments 1 and 3) or a later onset (experiments 2 and 3) relative to the other harmonics, at different timing asynchronies from 0 ms (no asynchrony) to 200 ms. In all experiments, tones were presented in a two-alternative forced choice paradigm asking participants which “sound file” had more sounds. Results suggest that there is a dependence of duration conditions on binding and amplitude envelope plays an important role when offset asynchrony is introduced. These results further suggest that our perception of auditory binding is affected by the structure of a sound’s amplitude envelope. These novel findings provide insight into the role amplitude envelope plays in gestalt grouping.

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