Reflection of bounce phenomenon in TEOAE in humans: dependence upon test-stimulus parameters.

The bounce phenomenon signifies an alteration of hearing after presentation of low-frequency loud tones. Generally, it implies an initial improvement and a following reduction in auditory sensitivity that reaching peaks at 1- and 3-min intervals of the post-exposure time, respectively. The dependence of the bounce upon test-stimulus parameters has been investigated in the present study. Normally hearing subjects were tested and transiently evoked otoacoustic emissions, TEOAEs, were utilized for an objective assessment of the event. Clicks and tone-pips served for test-stimuli, i.e. for TEOAE registrations, while a tone of 250-Hz frequency and of 95-dB SPL intensity has been exposed during 3 min for the bounce initiation. Post-exposure TEOAE changes were more prominent at lower than at higher test-stimulus intensity, 15 vs. 35 dB nHL. The differences concerned both phases of the bounce, augmentations and reductions. On the other hand, under different test-stimulus frequencies, 250, 500, and 2000 Hz, the bounce, particularly augmentations, owned similar magnitudes. It has been concluded thus that the mechanism of the bounce, particularly of its augmentation phase, is global and covers all cochlear regions, tuned to different sound frequencies.

Reflection of bounce phenomenon in DPOAE: a human study.

The behavior of distortion product otoacoustic emission, DPOAE, has been studied in normally hearing subjects after application of a tone of 0.25-kHz frequency and of 80-dB nHL intensity during 3 min. The bounce phenomenon has correspondingly been investigated just in humans and just via the objective approach. The reliable augmentation of DPOAEs was observed at 0.5 min after the cessation of exposures, the amount of increments being statistically equal at different DPOAE frequencies, 0.75, 1, 1.5, and 2 kHz. At 2 and 4 min after the exposure, in contrast, DPOAE magnitudes were shown to be similar to those of pre-exposure recordings. The present DPOAE results were matched with the previous data on transiently evoked otoacoustic emission and no principal differences have been found between.

Reflection of bounce phenomenon in TEOAE in humans: dependence upon exposure parameters.

The bounce phenomenon is an alteration of hearing acuity after presentation of loud tones. Generally, it implies the improvement in hearing acuity that followed by the worsening. The dependence of the bounce upon exposure stimulus parameters has been evaluated in the present study. Normally hearing subjects were investigated, while transiently evoked otoacoustic emission, TEOAE, has been recorded to estimate the event objectively. In the 1st experiment, the bounce indices have been compared under different intensities, 55-100 dB SPL, of exposure-tone of 250-Hz frequency. At lower intensities, 65-75 dB SPL, the augmentation phase in TEOAE bounce reflections exceeded the depression one. At higher intensities, 80-95 dB SPL, both phases of the bounce were of similar magnitudes. The event appeared thus bipolar and symmetric. At the highest intensity, 100 dB SPL, TEOAE drop has hardly been preceded by any augmentation. In the 2nd experiment, the bounce manifestations have been compared under different exposure-tone frequencies, 250, 500, and 2000 Hz. Under 250- and 500-Hz frequencies, the bounce was of similar magnitudes. Under 2000-Hz frequency, a conventional bounce has not been seen, a trend to the overall TEOAE decrement being observed only. The bounce mechanism is discussed and its complex rather than simple nature is considered.

The proper time for hearing screening in newborns.

The proper time for hearing screening in newborns via recordings of transiently evoked otoacoustic emission, TEOAE, has been estimated. 269 healthy neonates were investigated during five consecutive days after birth. On the first day, the results of screening were positive in 51 newborns only, 19.0%. In the following days, the number of the positive results systematically grew. In all inspected newborns, 100.0%, the TEOAE procedure was positive on the fifth day only. The fifth and following postnatal days are considered thus to be an appropriate time for hearing assessments in neonates.