Publication Date

2013-05-02

Availability

Open access

Embargo Period

2013-05-02

Degree Name

Master of Science (MS)

Department

Biomedical Engineering (Engineering)

Date of Defense

2013-04-11

First Committee Member

Ozcan Ozdamar

Second Committee Member

Jorge Bohorquez

Third Committee Member

Suhrud M. Rajguru

Abstract

Psychophysical detection of silent gaps embedded in ongoing steady sounds is commonly used to measure temporal resolution in hearing tests. Long latency auditory responses to such gaps in a noise signal are routinely investigated as electrophysiological measures of temporal resolution. This study was conducted to investigate the characteristics of early transient responses (Auditory Brainstem and Middle Latency) as well as Auditory Steady State Responses to such stimuli. Young subjects were monaurally stimulated by three different duration (12ms, 9ms, 6ms) of silence gaps in a white noise. All stimuli in this study were presented with 40 Hz stimulation rate in isochronic or jittered sequences. Quasi ASSRs were deconvolved using the CLAD (Continuous Loop Averaging Deconvolution) algorithm to obtain early transient responses to individual gaps (Delgado & Ozdamar, 2004). Responses to conventional clicks were also recorded. All subjects evoked identifiable early transient responses characterized by two positive and three negative peaks (Ng1,Pg1, Ng2,Pg2,Ng3). Peaks were about 25 ms apart and the first positive peak Pg1 was the most prominent. Results suggest that early responses to gaps in noise are composite ABR and MLR responses generated by noise onsets and offsets. Amplitudes and latencies of early transient responses and ASSR were affected by gap duration.

Keywords

gap; MLR; ASSR; Temporal resolution; noise; ABR; auditory

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