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Amplitude growth function of the acoustic reflex in young adults with auditory processing disorders

Grant number: 21/00779-4
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): August 01, 2021
Effective date (End): July 31, 2022
Field of knowledge:Health Sciences - Speech Therapy
Principal researcher:Renata Mota Mamede Carvallo
Grantee:Bárbara Magalhães da Silva
Home Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil


The acoustic reflex of the stapedius muscle is the result of strong sound stimulation. Its threshold corresponds to the lowest intensity of the activating stimulus capable of producing this muscle contraction, thus modifying the middle ear immittance. The acoustic reflex functions, among others, are related to the improvement of auditory attention and speech intelligibility and the attenuation of the effect of environmental noise on speech comprehension. Central Auditory Processing (CAP) is responsible for the analysis and interpretation of the sound stimulus (detection, discrimination, location, figure-background, and recognition). An individual with Auditory Processing Disorder has impairments in speech, reading, writing, language, and social behavior. The same structures responsible for the reflex arc also act on the physiological mechanisms of CAP skills, which determines an interrelation between changes in CAP skills and the absence of acoustic reflex. Objective. The aim of this study is to analyze the increase in the amplitude of the acoustic reflex in response to the growth of the contralateral stimulus in dB in young adults with auditory processing disorders. Method. Twenty young adults, aged between 18 and 30 years old, will participate in the study with the absence of alterations in the middle ear verified by tympanometry (type A curve), normal hearing thresholds (0 to 20 dBHL), presence of IPSI acoustic reflex or contralateral and absence of changes in the external auditory canal visible at microscopy. Participants will be submitted to anamnesis, microscopy, pure tone audiometry, speech tests, duration pattern, tympanometry, and research of acoustic reflexes. The acoustic reflexes will be registered contralateral to the submission of an activating stimulus used to trigger the reflex, in the frequencies of 1000, 2000, and 4000Hz including broadband noise (RB). The reflex will be considered present at the lowest intensity that generates a reflex response with a slope> 0.02ml, with typical morphology. The growth function of the acoustic reflex will be investigated in each of the frequencies of activating stimuli. A stimulus will be presented for approximately two seconds at an intensity of 70dBHL. The stimulus will be added in steps of 5dBHL up to 105dBHL and the slope amplitude values will be noted for each researched intensity. Therefore, the reflex will be considered absent when the slope> 0.02 at the maximum stimulator intensity is not reached. 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)

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