Estudio de la correlación existente entre el efecto supresor contralateral y la fatiga auditiva mediante otoemisiones acústicas transitorias.

Abstract

Introduction: The identification of capable persons to the action of the noise is one of the aims of the preventive labour medicine, the accomplishment of the audiometry to the workers exposed to noise is a complementary test for the valuation of the auditory fatigue, the sonorous trauma and the hipoacusia produced by noise, but it does not detect the functional alterations of the cells hair induced by noise in initial and still reversible stages, on the contrary the otoacoustic emisions can detect changes in primary stages and therefore reversible. Material and methods: We analyze the influence that the ipsilateral and contralateral otoacoustic stimulation exercises, valuating the suppressing contralateral effect and the auditory fatigue for the record of the transient otoacoustic emissions for a sample of 67 human ears. We made the record in three conditions: Without stimulus, with otoacoustic contralateral lateral stimulation and after otoacoustic ipsilaterallateral stimulation. The persons who present a high suppressing contralateral lateral effect, should not present auditory fatigue and viceversa, thus individuals would have a protection from the exhibition to the noise. Results: The ipsilateral or contralateral otoacoustic stimulation are capable of causing modifications of the activity coclear objetivable through reductions of he TEOAE. In 80,6 % of the cases in which reductions of amplitude > 0,5 dB take place, they only appear in one of the two records obtained under the influence of the otoacoustic stimulation. There is a negative statistically significant correlation between the suppressing contralateral effect and the auditory fatigue. Discussion: The amplitud of the TEOAE diminishes when an otoacoustic stimulation uses ipsilateral and contralateral, due to the modulating role of the medial efferent system on the cells hair. The suppressing contralateral effect influences directly on the minor susceptibility to the auditory fatigue and viceversa, when an important suppressing effect unleashes the ear is less capable to the auditory fatigue through a minor transient change of the auditory threshold or for a reduction in the extent of the TEOAE.