Amplitude growth function of the acoustic reflex in young adults

• Grant number: 21/00180-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2021
• End date: September 30, 2023
• Field of knowledge: Health Sciences - Speech Therapy
• Principal Investigator: Renata Mota Mamede Carvallo
• Grantee: Karina Camilo
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The acoustic reflex threshold measures the lowest sound level that triggers a middle ear response. If the magnitude of the response for each sound level is plotted on a graph, the growth curve of the amplitude of the acoustic reflex can be plotted. People with auditory function integrity are expected to show a typical growth curve pattern. Thus, in addition to the acoustic reflex threshold measurements and the clinical value of the presence or absence of this reflex, it is also relevant to study the typical growth pattern of this reflex in young adults, so that later it can be a reference for other populations and of different hearing conditions. Objective. The aim of this study is to analyze the growth of the acoustic reflex amplitude, in response to the growth of the contralateral auditory stimulus in young adults without hearing complaints. Method. Twenty young adults, aged between 18 and 30 years old, will participate in the study, with normal hearing thresholds (0 to 20 dBHL), absence of alterations in the middle ear verified by tympanometry (Curve type A), presence of acoustic reflexes, and, with no exposure to loud noise (work or recreational). Participants will be submitted to anamnesis, meatoscopy, pure tone audiometry, speech tests, tympanometry, and acoustic reflex research. The acoustic reflexes will be registered contralateral to the presentation of an activating stimulus used to trigger the reflex, in the frequencies of pure tones of 1000, 2000, and 4000Hz and of broadband noise (RB). The reflex will be considered present at the lowest intensity that generates a reflex response with a slope equal to or greater than 0.02 ml, with typical morphology and without evidence of artifact. The test will start with the presentation of the stimulus for approximately two seconds at an intensity of 70 dBHL, with the intensity level decreasing in steps of 10 dBHL until the reflex is extinguished and then added in steps of 5 dBHL until the threshold. The temporal parameters of the stimuli will be adjusted in the equipment as follows: 0.2 ms rise time; 1.3 ms plateau and 0.5 ms fall time. Analysis of Results. The results will be submitted to descriptive and inferential analysis, with analysis by ear, gender and frequency tested. The 0.05 significance level will be adopted, and the results that present a statistically significant difference will be marked with an asterisk (*). (AU)