Binaural interaction of stapedius reflex

Time-compressed speech test in adults with and without central auditory processing disorders

ABSTRACT Purpose: to analyze and compare the performance in the time-compressed speech test and the auditory behavior of adults with and without central auditory processing disorders. Methods: an observational, analytical, cross-sectional study with a total of 40 people of both genders aged 18 to 35 years participating in the study. They were submitted to anamnesis, basic audiological assessment, and a core battery of tests for central auditory processing - including the dichotic digits test (binaural integration), frequency pattern test, and time-compressed speech test (TCST). Based on the results of the dichotic digits and frequency pattern tests, the subjects were divided into two groups, with and without central auditory processing disorders. The auditory behavior was assessed with the Scale of Auditory Behavior (SAB) questionnaire. The Mann-Whitney and Fisher’s exact tests were used for the statistical analysis, setting the significance level at p < 0.05. Results: no difference in performance was found between the groups regarding the ears. There was a difference between the groups only in the time-compressed speech test with monosyllable stimuli in the left ear (p = 0.026). Monosyllables were the words that resulted in most errors. Conclusion: it was verified that only the list of stimuli influenced the performance, differing the individuals with and without central auditory processing disorders. There was an association of auditory behavior, analyzed with the SAB questionnaire, with the performance in the TCST with the list of monosyllables. It is suggested that this list be used when assessing adults by the time-compressed speech test.

Mięsień strzemiączkowy – aktualne poglądy na temat anatomii i fizjologii

The authors present current opinions about anatomy and physiology of the stapedius muscle and its role of the hearing process. The stapedius muscle is the smallest striped muscle of the human body and contracts reflexive in response to acoustic stimulation. The stapedius muscle puls the neck of the stapes in the direction of the stapedius tendon. This movement causes stiffening of the incus and the malleus and also changes the pressure of the perilymph in the inner ear. This is the protective inner ear action of the stapedius reflex against hearing damage by noise. The stapedius reflex shows bilateral interactions and its center is located in the brainstem. The binaural interaction of the stapedius reflex plays an important role in the maintaining of the sound direction. The stapedius tendon also plays role in the vascularization of the long process of the incus.