Abstract
Transient otoacoustic emissions (TEOAEs) and wideband pressure reflectance were simultaneously measured in 24 young normal-hearing listeners. Contralateral acoustic stimulation (CAS) was delivered across a wide range of levels (36-78 dB SL) to activate the medial olivocochlear reflex (MOCR) and middle-ear muscle reflex (MEMR). The resulting measurements were analyzed in terms of changes in frequency, magnitude, and phase. Changes in wideband reflectance were systematic across levels within individuals, but highly variable across subjects. These changes may provide a sensitive measure of middle-ear muscle reflex activation, but do not appear to be helpful in disentangling the effects of the two reflexes on TEOAEs. Frequency changes in TEOAEs occurred in about a third of measurements, but did not appear to be systematically related to CAS level and showed both increases and decreases. Frequency shifts occurred more often in the presence of MEMR. Changes in TEOAE magnitude and phase, after accounting for frequency changes, are reported. Average shifts at the highest CAS level were -4.4 dB and 0.22 cycles of phase lead.