Otoacoustic emission as an early hearing loss indicator

Project Details


Over-exposure to noise is considered to be one of the main causes of hair cell
damage in the inner ear and can result in temporary and permanent deterioration
of the hearing. Otoacoustic emissions (OAEs) are a by-product of the active
mechanism of the outer hair cells and a sensitive measure of that cochlear
function. Reported measurements of OAEs before and after noise exposure suggest
that OAE is a more sensitive measure for the hearing function than pure-tone
audiometry and therefore might be a measure for the early identification of
hearing loss. In this study distortion product OAEs (DPOAEs) were obtained for
subjects of different ages and different exposure history. Also DPOAEs were
obtained before and after exposing subjects to a high level sound, which causes
a temporary shift in the state of hearing. A classification algorithm was
developed, which identifies and describes the chcaracteristics of DPOAE fine
structure ripples. A relation between DPOAE level and the state of hearing could
be observed in the present study. DPOAE levels are reduced after an over-
exposure and have highest levels in the group of youngest subjects. The DPOAEs
of all tested subjects feature the typical fine structure pattern. The fine
structure pattern is highly individual and stable over time. No unequivocal
relation between the characteristics of the DPOAE fine structure and the state
of hearing could be found, e.g. for some subjects and increase of ripple height,
and for other subjects a decrease of ripple height could be observed after an

See also project concerning prevalence of DPOAE fine structure. Supported by
Ph.D. scholarship by the Oticon Foundation and STVF/FTP.

Effective start/end date31/12/200631/12/2006


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