Background and ObjectivesNumerous studies have indicated deterioration of speech perception in noisy conditions among the elderly even those with normal hearing capabilities. The aim of this study was to investigate the effects of age on the speech-in-noise identification by speech-in-noise (SIN) test, subjective ratings of hearing difficulties by speech, spatial, and qualities of hearing scale (SSQ) questionnaire and encoding of fundamental frequency (F0) by Speech auditory brainstem response (ABR) in the elderly and comparing the results with young people.Subjects and MethodsThe present study was conducted on 32 elderly people aged over 60 years old (17 male and 15 female) with the mean age of 68.9 (standard deviation=6.33) possessing normal peripheral hearing and 32 young subjects (16 male and 16 female) aged 18-25 years old.ResultsFindings showed that the score of SIN test is lower among the elderly people as compared with young people in signal-to-noise ratios of 0 and -10 based on Iranian version of SSQ questionnaire (p<0.001). The range of F0 amplitude in the elderly people is also lower than young people (p<0.001) in Speech ABR.ConclusionsIt seems that speech processing in older people is deteriorated comparing with young people regardless of their normal peripheral auditory thresholds. This decrease will result in weaker perception and improper segregation of speech from other competing sources.

The timing of speech-evoked responses is not related to the stimulus presentation mode; however, binaural stimulation produces more robust responses. Lateral asymmetry in the representation of speech elements was not considerable at the brainstem level.

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Objective: To investigate how tinnitus affects the processing of speech and non-speech stimuli at the subcortical level. Study Design: Cross-sectional analytical study. Setting: Academic, tertiary referral center. Patients: Eighteen individuals with tinnitus and 20 controls without tinnitus matched based on their age and sex. All subjects had normal hearing sensitivity. Intervention: Diagnostic. Main Outcome Measures: The effect of tinnitus on the parameters of auditory brainstem responses (ABR) to non-speech (click-ABR), and speech (sABR) stimuli was investigated. Results: Latencies of click ABR in waves III, V, and Vn, as well as inter-peak latency (IPL) of I to V were significantly longer in individuals with tinnitus compared with the controls. Individuals with tinnitus demonstrated significantly longer latencies of all sABR waves than the control group. The tinnitus patients also exhibited a significant decrease in the slope of the V-A complex and reduced encoding of the first and higher formants. A significant difference was observed between the two groups in the spectral magnitudes, the first formant frequency range (F1) and a higher frequency region (HF). Conclusions: Our findings suggest that maladaptive neural plasticity resulting from tinnitus can be subcortically measured and affects timing processing of both speech and non-speech stimuli. The findings have been discussed based on models of maladaptive plasticity and the interference of tinnitus as an internal noise in synthesizing speech auditory stimuli.

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