Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Health and Rehabilitation Sciences

Supervisor

Purcell, David W.

Abstract

Auditory temporal acuity, a listener’s ability to discriminate rapid changes in the envelope of an auditory signal over time, is crucial for understanding speech. Electrophysiological measurement of auditory temporal acuity is beneficial when we cannot achieve reliable behavioural responses. The envelope following response (EFR) evoked by a changing (swept) amplitude-modulated (AM) stimulus is significantly correlated with behavioural measures of temporal acuity in humans. Previous research using AM broadband noise carriers may have been affected by the cancellation of evoked potentials at the measurement electrodes due to out-of-phase interference of parallel responses initiated at different times due to cochlear travelling wave timing differences. This study aimed to examine the possibility of using narrow-band noise carriers with different center frequencies, which enables recording of EFR from low, mid and high-frequency cochlear regions individually, while the modulation frequency gradually varied over time, and to determine whether we can improve the previously proposed objective method in three groups of normal-hearing participants.

Keywords

Electrophysiological measurements, temporal acuity, envelope following response (EFR), narrow-band noise carrier, normal hearing adults

Summary for Lay Audience

Auditory temporal acuity refers to the sensitivity of the human auditory system to fluctuations in the loudness of a sound over time, which is essential for speech perception. The envelope following response (EFR) is brain activity that can be recorded while special sounds are presented to the listener. It is measured from surface electrodes placed on the human scalp. In our study, special noise sounds that fluctuated in loudness were used to elicit EFRs. The maximum rate at which the sounds could fluctuate and still caused a detectable EFR was compared with people’s ability to notice the fluctuations behaviorally. The purpose of the study was to investigate how the EFR varies with the frequency content of sound, and whether some frequencies obtain a better correlation with behavioural measurements. This research contributes to our understanding of how sound is processed in the brain over time.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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