A distortion product otoacoustic emissions (DPOAE) assessment of cochlear function in tinnitus subjects with normal hearing sensitivity

Tinnitus, the perception of sound in the absence of an external acoustic source, disrupts the daily life of 1 out of every 200 adults, yet its physiological basis remains largely a mystery. While tinnitus and hearing loss (i.e., elevated pure tone thresholds) commonly co-occur, many people without hearing loss experience tinnitus, raising the question of whether cochlear pathology is always a prerequisite for this percept. This study used distortion product otoacoustic emissions (DPOAEs) to evaluate the cochlear amplifier of 13 tinnitus subjects and 13 non-tinnitus subjects (matched by age, sex, and audiogram) across a broad range of frequencies and intensities. DPOAE magnitudes were measured for at least 52 frequencies (500 Hz <f2 5 8 kHz, with f2ff=1.2) and nine intensities (20 dB < L2 5 60 dB, with L, = 39 + 0.4L2) in each ear. Further, this study only considered ears with normal audiograms and unremarkable history so that any abnormal findings could not be attributed large-scale hair cell damage within the cochlea. Consistent differences in the shape of the DP-gram (DPOAE magnitude as a function of presentation frequency, f2) were found in tinnitus subjects. A quantitative method for assessing DP-gram shape was developed, and statistical analyses were performed to determine whether tinnitus or other patient characteristics correlated with the abnormal DP-gram shape. The data collected in this study suggest peripheral auditory malfunction in tinnitus subjects with normal audiograms.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Acker, Leah C. (Leah Christine)

Advisor dc:contributor.advisor

• Jennifer Melcher and Christopher Shera.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/53201

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/53201