An externalized sound is one that is perceived outside the head, whereas an internalized sound is perceived inside the head. The effect of hearing aids on these phenomena was investigated through psychoacoustic experiments, a novel questionnaire and offline analyses. The importance of high-frequency pinna cues for externalization in normal-hearing and hearing-impaired listeners was investigated using open-ear simulations of different microphone placements, frequency responses, and the number of talkers. It was found that hearing-impaired listeners experienced a compressed or "flattened" perception of externalization in relation to pinna cues. The role of changes in the stimulus and source direction on the perception of externalization by hearing-impaired listeners with and without their hearing aids was also investigated. An effect of angle but no effect of hearing aids was found for hearing-impaired listeners. The effect of short-term acclimatization to hearing aids by normal-hearing listeners performing the same task was investigated; an effect of acclimatization was found. A questionnaire was developed to determine the prevalence of internalization in several situations. The prevalence of internalization increased with the number of hearing aids worn. The overall prevalence for any experience of internalization was 25% of the sample population. The effect of dynamic-range compression, signal type and listening environment on a potential indicator for internalization, the shape of the interaural-level-difference distribution, was analyzed. The analyses only indicated potential internalization under particular constraints related to listening environment and temporal resolution, not dynamic range compression.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:632711 |
| Date | January 2014 |
| Creators | Boyd, Alan William |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24371 |
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