Training in OAE

Pressurized otoacoustic emissions measurement in patients with eustachian tube dysfunction

10 mins
08 February 2022


Summary of: Trine, M. B., Hirsch, J. E., & Margolis, R. H. (1993). The effect of middle ear pressure on transient evoked otoacoustic emissionsEar and hearing14(6), 401–407.

Otoacoustic emissions (OAEs) are soft signals generated by vibrations in the cochlea, which are transmitted via the middle ear and recorded as acoustic energy in the ear canal. Since OAE transmission occurs via the middle ear, middle ear dysfunction, as in the case of negative middle-ear pressure, can impede the detection of the OAE response. This is not surprising given that negative middle-ear pressure can also increase audiometric hearing thresholds, particularly for frequencies below 2000 Hz. The goal of this paper is to observe the effect of negative middle ear pressures under -100 daPa in ears with hearing thresholds within 30 dB HL. Compared to measurements obtained at ambient pressure, the overall level of transient-evoked OAEs (TEOAEs) are 1.15 to 6.8 dB greater when the ear canal is pressurized to compensate for negative middle-ear pressure. Likewise, TEOAE reproducibility increases from 2 to 41% with compensation for negative middle-ear pressure. Failing to compensate for negative middle-ear pressure reduces the TEOAE response by approximately 15 dB from 500 to 750 Hz, 5 dB from 1000 to 2000 Hz, and has minimal or no change in the TEOAE response from 3000 to 4000 Hz. Finally, compensation for negative middle-ear pressure reduces stimulus ringing in the ear canal and produces a smoother stimulus spectrum. These findings suggest that compensation for negative middle-ear pressure improves TEOAE amplitude, reproducibility and stimulus spectral characteristics. Importantly, this has the effect of reducing false positive TEOAE responses.


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