The Influences of Contralateral Acoustic Stimulation on Spontaneous Otoacoustic Emissions

Abstract

Objective:To investigate the influences of contralateral acoustic stimulation on amplitudes and frequencies of spontaneous otoacoustic emissions (SPOAEs).Materials and Methods:Twenty voluntary participants with normal hearing and unilateral SPOAE were included in the study. Emissions were recorded before and during stimulation of contralateral ear with 75 dB SPL white-noise.Results:From 20 cases, thirty SPOAEs with amplitudes ranging between - 6 to 19 dB SPL (mean: 6.3 dB SPL) and with a mean frequency of 1925 Hz were recorded. During contralateral stimulation, the mean amplitude and frequency of SPOAEs were found to be 3.6 dB SPL and 2004 Hz respectively. The suppressive effect of contralateral noise on SPOAEs were present at all frequencies with a higher significance in 1 to 3 kHz frequency range. In all SPOAE frequencies, an upward shift was noted during contralateral acoustic stimulation.Conclusion:Acoustical stimulation of efferent innervation of the cochlea causes alterations in its active micro-mechanics and therefore in amplitudes and frequencies of SPOAEs with a frequency selective manner.

Keywords

• spontaneous otoacoustic emissions
• efferent innervation
• contralateral stimulation.