Abstract
Rationale: Effective management of individuals with auditory neuropathy spectrum disorder (ANSD) is always a challenge for audiologists due to the heterogeneity of the disorder in terms of perception deficits and pathophysiology. The present study was undertaken to apprehend the feature transmission index in terms of different signal enhancement strategies and modality of presentation to develop specific management strategies for the target group. Design: Repeated measure standard group comparison design was utilized for the present study. Clinical group had 40 participants with confirmed diagnosis of ANSD and the control group included 40 individuals with normal auditory abilities. Stimuli tested were plosives, /k/, /ṭ/ /p/, /b/, /ḍ/ and /g/. These stimuli were acoustically enhanced, which includes both companding and envelope enhancement. The perception of both the unprocessed and acoustically enhanced stimuli was studied in the auditory alone (A), visual alone (V) and, the auditory-visual (AV) modalities. In the A and AV, modalities perception was studied both in quiet and 0 dB SNR conditions, whereas in the visual modality perception was studied only in quiet for the unprocessed stimuli. Sequential information analysis was carried for each stimulus, modality and condition using the FIX software. Results: SINFA result showed that the place and voicing feature transmission and the total information transmitted is lesser in ANSD for the stimulus, modality and condition compared to control. The results were comparable for the acoustically enhanced stimuli in both the groups. AV modality transmitted higher place and total information compared to an auditory or visual modality in both groups. Additional visual cues have an added advantage in ANSD compared to control, and this was more pronounced in the 0 dB SNR condition. Conclusion: Signal enhancements in the current form revealed negligible improvement in feature transmission in ANSD and control. The result that AV modality improved feature transmission in ANSD brings out the need to facilitate both the auditory modality and visual modality for the successful management of ANSD.