Pk. Plinkert et al., INFLUENCE OF STATIC MIDDLE-EAR PRESSURE ON TRANSIENTLY EVOKED OTOACOUSTIC EMISSIONS AND DISTORTION PRODUCTS, European archives of oto-rhino-laryngology, 251(2), 1994, pp. 95-99
Otoacoustic emissions (OAE) are influenced in their amplitude and freq
uency spectra by the middle ear. The effects of changes in the middle
ear transmission mechanisms on transiently evoked OAE (TEOAE) and dist
ortion product emissions (DPOAE) were investigated as a function of st
atic ear canal pressure in 25 normal-hearing test persons aged 18-35 y
ears. The ear canal pressure was varied stepwise between positive and
negative values of 200 daPa. TEOAE and DPOAE amplitudes were attenuate
d significantly with changes of the static ear canal pressure, with gr
eatest changes at low frequencies (< 2 kHz). The alterations of OAE am
plitude were slightly dependent on the polarity of the pressure, with
positive pressure producing a greater attenuation (0.6 dB). The result
s demonstrate that changes in middle ear impedance can cause a misinte
rpretation of OAE. To avoid this problem, tympanometry should always p
recede OAE measurements. Alternatively, both methods can be combined u
sing one acoustic probe, so that the emissions can be evoked at the pe
ak of middle ear compliance.