Alpha Omega Alpha Honor Medical Society

2012 Research Abstract

Musical Instrument Identification in Cochlear Implant Users: A Psychophysical Study of Acoustic Changes

Investigator: Tanner Fullmer, Medical College of Wisconsin

Mentors: David R. Friedland, MD, PhD, and Christina Runge, PhD, Medical College of Wisconsin

Cochlear implants (CIs) offer many deaf individuals greater opportunity to interact with their environment, but there are still shortcomings in the user’s ability to perceive sound, particularly music. The purpose of this study was to examine CI users’ ability to identify instrument changes absent of temporal cues, and to evaluate auditory evoked potentials (AEPs) in response to those changes. Sample notes from 5 instruments (clarinet, flute, violin, saxophone, and trumpet) were trimmed to only include the center 500ms, normalized, and pitch shifted. Random combinations of these instrument stimuli were concatenated and subjects were asked to identify the sounds as same or different. Ten experienced adult CI users and four normal hearing (NH) controls were administered the tests. Percent correct scores and sensitivity indices (D’) were compared between groups. Finally, AEPs were measured on 4 NH subjects in response to clarinet-trumpet changes with a simple 4 electrode montage. CI subjects had lower identification scores on all tests and instrument combinations. However, both groups followed similar patterns in terms of which instruments seemed to be the easiest or most difficult to differentiate: clarinet-saxophone combinations were most difficult (NH D’=1.70, CI D’=.85), while both groups correctly distinguished flute-trumpet combinations over 99% of the time. Statistically significant differences were seen comparing NH and CI D’ scores for trumpet-violin, flute-saxophone, and clarinet-saxophone combinations. Interestingly CI identification scores did not correlate with previously obtained speech scores (R=.28). AEPs with distinct onset responses and acoustic change complexes were recorded in four NH individuals in response to clarinet-trumpet changes.CI subjects have a baseline lower capacity to perceive instrument changes. However, they struggle with the same instrument combinations as NH individuals. AEPs can be recorded in response to instrument changes, but more needs to be done to evaluate their usefulness on CI subjects, and correlate them with behavioral data.

Updated on March 28, 2013.

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