Abstract:
The medial olivocochlear bundle modulates cochlear activity. Its activation by contralateral stimulation produces measurable changes in otoacoustic emission (OAE) and cochlear microphonics (CMs). We hypothesized that focusing attention on an auditory task might augment efferent activity and thus change medial olivocochlear-mediated influences on OAE and CMs.
31 participants were recruited for the study. Transient-evoked otoacoustic emissions (TEOAEs) and CMs were evoked in a quiet (baseline) condition, and during two contralateral acoustic stimulation task conditions: active listening and passive listening. The magnitude of the medial olivocochlear reflex was indexed by the changes in TEOAE and CM amplitude.
TEOAE amplitudes were inhibited by contralateral noise in both active and passive conditions. CM amplitudes were significantly enhanced by contralateral noise in both conditions. The medial olivocochlear reflex strength (based on TEOAE inhibition or CM enhancement) did not differ between active and passive listening. Correlation analysis revealed no relationship between the OAE-based and CM-based medial olivocochlear reflex measures. These findings confirm that contralateral noise elicits expected medial olivocochlear-mediated changes, supporting the validity of both metrics as indices of efferent function. However, the strength of the medial olivocochlear reflex strength was not modulated by attention.
