The effects of sub-unit formation on adult listeners' ability to notice changes in a continuously changing timbre (with fixed fundamental frequency) were studied. In Experiment 1, reaction times were recorded when listeners were asked to detect a change in the timbre of a 5-sec sound with spectral content that gradually shifted across time producing a perceptual change from "dull" to "bright." Sixteen silences were inserted in some conditions to cause the formation of short units. Listeners noticed the change sooner in these conditions than when the transitions were unbroken or broken by loud noise bursts. Experiments 2 and 3 looked at the individual unit and considered two separate processes as possible explanations for the previous results. Process 1 accentuates stimulus properties present at moments of onset and offset. Process 2, instead, uses onsets and offsets to signal the beginnings and ends of units and reduces the change perceived within a unit. The former would imply that listeners made onset comparisons in a point-to-point manner, whereas the latter would imply that the onsets, which formed units, enabled a unit-to-unit comparison. In Experiments 2 and 3 listeners were asked to distinguish between 1-sec sounds that both started with Timbre 1 and ended with Timbre 2, but were different in their internal rates of timbral change. Listener's performance was significantly poorer when asked to distinguish between two sounds that had identical onset and offset information in comparison to their performance when asked to distinguish either the first halves or second halves of these, which would differ in onset or offset information. Evidence suggests the presence of both Process 1 and Process 2.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.30156 |
| Date | January 1999 |
| Creators | Crum, Poppy. |
| Contributors | Bregman, Hilbert S. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Arts (Department of Psychology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001746684, proquestno: MQ64138, Theses scanned by UMI/ProQuest. |
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