![]() ![]() ![]() The MATLAB-generated stimuli were presented to the participants through a clinical audiometer (GSI-61). All participants were recruited into the study after approval from the Institute Ethics Committee of the National Institute of Mental Health & Neurosciences, Bangalore, India (No. After recruitment into the study, the normal hearing participants underwent all the tests as subjects in the ANSD group except hearing aid fitting. Normally-hearing participants showed pure tone thresholds of less than 20 dB HL (ISO 389) (3-frequency average -500, 1,000 and 2,000 Hz), speech identification scores >95% at 40 dB SL (ref: pure tone average), ‘A’ type tympanogram with reflexes present at normal sensation levels, identifiable ABRs (waves I, III, and V) at normal latencies, and normal TEOAEs. The normally-hearing participants underwent the same tests as participants with ANSD for inclusion into the study. A routine clinical examination ruled out any neurological or otological problem. A structured interview confirmed that persons in the normally-hearing (control) group had no difficulty in hearing/understanding speech in daily listening conditions. All the participants spoke Kannada–a Dravidian language–spoken by about 70 million people predominantly in the South Indian state of Karnataka.įorty normally hearing individuals matched for age, gender, education, socioeconomic status and language-spoken with those in the experimental group served as controls. ![]() Twenty-nine persons reported gradual onset of the problem while it was sudden in the remaining. Participants with ANSD in the present study showed poor speech identification in both quiet (n=37) and in noise (n=38). Six persons reported hyperbilirubinemia (report of having jaundice), but no information relating to etiology of the problem could be ascertained from others. None of the participants had any family history of the problem. However, the reliability of this information is questionable as there are no medical records to back the assertion. Age of onset of the problem ranged from 9 to 29 years (mean age of onset=16.08 years). Participants included both males (n=25) and females (n=13). In the final analysis, thirty-eight individuals, aged between 16 and 30 years (mean age=22.38 years) and with a confirmed diagnosis of ANSD participated in the study. reported higher number of males (56%) than females (44%) affected with ANSD.ĭetailed information was elicited on the age of onset of the problem, characteristics of the hearing problem and history of intervention, if any. Furthermore, presence of cortical potentials was associated with increased benefit from hearing aids. also reported a ‘rising’ pattern of pure tone audiogram and good speech identification in individuals in whom cortical potentials could be recorded. reported the opposite of this (female to male ratio of 1.25:1). While Kumar and Jayaram reported a greater prevalence of the problem in males compared to females, Narne, et al. who reported less than 10% of instances of onset in individuals between 16 to 18 years. who reported a mean onset age of 21.03 years (adolescence and adulthood) in 82% of their subjects while the remaining showed a childhood onset. This observation was subsequently corroborated by Narne, et al. Fifty-nine percent of the subjects in the study reported to have had the onset of the problem between 14 and 24 years signifying late onset of the problem in India. Kumar and Jayaram reported a ‘peaked’ audiogram as the most common pure tone configuration, widely varying speech identification scores, an association between ‘peaked’ audiogram with better speech identification scores, and no association between speech identification scores and OAEs/ABRs in their participants. ANSD was diagnosed on the basis of criteria of Starr, et al. Kumar and Jayaram, in a register-based retrospective study, reported a prevalence of 0.28% of ANSD in all the hearing impaired and 0.54% in individuals with permanent hearing loss.
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