Estudio de la supresión contralateral de las otoemisiones acústicas transitorias en jóvenes

Abstract

The medial efferent system, descending olivocochlear bundle discovered in 1979, regulates a reflex mechanism for cochlear protection against noise. Its function can be measured with the transient otoacoustic emission (TEOAE) contralateral suppression (CS) test, which provides information about auditory vulnerability to noise. The aim of this study was to analyze the mechanism of cochlear protection through the CS of TEOAE in young university students from Córdoba.

The study was descriptive, correlational, cross-sectional. We evaluated 37 young people between 18-25 years old, the sampling was for convenience. Young people were included with informed consent, normal middle ear, TEOAE present in at least three of five frequencies, and hearing rest for 8 hours. The procedures respected the ethical principles of the Declaration of Helsinki. Young people exposed to occupational noise assessed by an ad hoc hearing status questionnaire were excluded. The audiological tests were carried out in a mobile audiometric booth. TEOAE were recorded without and with contralateral acoustic stimulus (CAS) at 1000, 1500, 2000, 3000, and 4000 Hz. The CS was obtained from the total response differences between the amplitudes without CAS and with CAS. The right (RE) and left (LE) ears were classified according to the CS: >0 dB SPL (Suppressed-S) and ≤0 dB SPL (Not Suppressed-NS). To compare of total response amplitudes without and with CAS, T-test (paired) and Fisher test were applied. The level of significant difference was 0.05.

The results showed decreased CS in the total response in the condition with CAS in both ears, statistically significant differences were found in RE (paired t-test: p<0.0001). In the RE between groups S (n=32) and NS (n=5) and LE between groups S (n=26) and NS (n=11) in condition without and with CAS, the mean values were higher for group S in both ears, however, there were no statistically significant differences (Fisher's test: p>0.05).

In conclusion,  the CS test of TEOAE is a useful tool to identify subclinical indicators of hearing associated with the function of the medial efferent system and could contribute to the early detection of young people with vulnerable ears.