Medial olivocochlear reflex in adults: the effect on stimulus-frequency and transient otoacoustic emissions

• Grant number: 18/25931-0
• Support Opportunities: Regular Research Grants
• Duration: November 01, 2019 - October 31, 2023
• Field of knowledge: Health Sciences - Speech Therapy
• Principal Investigator: Renata Mota Mamede Carvallo
• Grantee: Renata Mota Mamede Carvallo
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Medial Olivocochlear Reflex (MOCR) is still poorly understood, although its action in inhibiting otoacoustic emissions has been explored since the 1980s. Its inhibitory effect results in otoacoustic emissions amplitude reduction when the efferent system is activated by noise. MOCR estimated by transient otoacoustic emissions (TOAE) is measured in decibels, but the percentage reduction measure in relation to emissions with no contralateral noise stimulation (NO- CAS) has been suggested. The measure of stimulus-frequency otoacoustic emissions (SFOAEs) is also based on the auditory efferent contribution to the acquisition of pure tone stimulus responses. The hypothesis of this study is that there would be a higher occurrence of SFOAEs in the group of ears with medial olivo-cochlear reflex (MOCR). Objective To analyze the inhibitory effect of the auditory efferent pathway on the responses of two different otoacoustic emission procedures, verifying the correspondence between the response level of the stimulus-frequency otoacoustic emissions and that of the transient otoacoustic emissions. Procedure The study will include 40 participants, aged between 18 and 35 years, with auditory thresholds not exceeding 15 dBHL at frequencies from 250 to 6000 Hz, and not exceeding 20 dBHL in the frequency of 8000 Hz, normal tympanometric curve (type A), otoacoustic emissions present at 60 dBSPL + 2 dB linear stimulus. The optoacoustic responses will be compared between conditions without and with contralateral noise at 60BSPL, in decibel and percentage. Next, the stimulus-frequency otoacoustic emissions test will be performed, and its results will be compared to the inhibitory effect on transient otoacoustic emissions. The results will be submitted to descriptive and inferential analysis, being performed the analysis by ear and gender, separately. The significance level of 0.05 will be adopted. (AU)