[Changes in transitory evoked otoacoustic emissions and acoustic distortion products in disorders of eustachian tube ventilation].

Middle ear impedance plays an important role in the retrograde middle ear transfer and interpretation of otoacoustic emissions (OAE). Changes of emission spectra and reproducibility or absence of sound emissions can be caused by middle ear dysfunction. To avoid misinterpretation, especially in infant screening, we combined measurements of transiently-evoked otoacoustic emissions (TEOAE), distortion products (DPOAE) and middle ear pressure. With a single acoustic probe ear canal baro-pressure was adjusted individually to the middle ear pressure, allowing OAE to be measured at maximum compliance of the middle ear. Fifty children (ages, 3-8 years) were examined with hypoventilation of the middle ear. Twenty-five normally hearing adults were also studied. Positive and negative middle ear pressures significantly attenuated the amplitude of low-frequency OAE (< 2 kHz), whereas high-frequency emissions were stable. Individual adaptations of static ear canal pressure eliminated these alterations of TEOAE and DPOAE.