First Advisor

Thomas Dolan

Term of Graduation

Fall 1990

Date of Publication

11-16-1990

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Speech Communication

Department

Speech Communication

Language

English

Subjects

Electrocochleography, Acoustic reflex -- Measurement, Hearing levels

DOI

10.15760/etd.5979

Physical Description

1 online resource (3, iv, 51 pages)

Abstract

The acoustic reflex refers to the contraction of a middle ear muscle in response to sound. The contraction causes a stiffening of the middle ear system and, consequently, the flow of acoustic energy to the cochlea is impeded. By measuring the change in admittance in the auditory system during sound stimulation it is possible to indirectly monitor the middle ear muscle contractions. Such measurements provide useful information regarding the integrity of the auditory system and the location of the auditory pathology.

In subjects with normal hearing sensitivity, the acoustic reflex is typically elicited at a sensation level of between 85 and 100 dB for frequencies below 4000 Hz. In subjects with cochlear hearing loss, reflexes are often evoked at SLs of between 15 and 70 dB. As such, reflexes elicited at reduced SLs signal the presence of cochlear hearing loss, at least for frequencies below 4000 Hz. When a hearing loss is present at a frequency above 4,000 Hz then testing using the lower frequency stimuli does not successfully differentiate the pathology. To date, most research on the acoustic reflex has involved stimulus frequencies in the 250 to 4,000 Hz frequency range, mainly due to instrumentation limitations. The purpose of this study was 1) to determine if there is a difference in the SLs at which the reflex is elicited in normal hearing subjects versus subjects with high frequency cochlear hearing loss, and 2) to examine the time course of the reflex elicited by high frequency stimuli.

Rights

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Comments

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Persistent Identifier

https://archives.pdx.edu/ds/psu/23550

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