c l i n i c a l e p i d e m i o l o g y a n d g l o b a l h e a l t h 5

Individuals with unilateral hearing loss of severe-profound degree face listening difficulties while localizing a sound source and while perceiving speech in the presence of noise. The objective was to compare the efficacy of the digitally programmable bone anchored hearing aid (BAHA), trimmer digital BAHA and the transcranial contralateral routing of signal (T-CROS) in improving the listening performance in adults with unilateral hearing loss. Twenty-four adults with unilateral hearing loss was assessed for sound field thresholds, speech perception performance in quiet and noise (direct and indirect conditions) and the subjective quality rating of speech in unaided and aided with either T-CROS or digitally programmable BAHA or trimmer digital BAHA attached to the headband. Results indicated that the participants performed better with both the digitally programmable and the trimmer digital BAHA than the T-CROS in both quiet and noise. However, the digitally programmable BAHA performed better when the speech arrived from the poorer ear side. The current study helps in prioritizing the hearing amplification devices for the trial and also helps in arriving at the appropriate hearing amplification device for the individuals with unilateral hearing loss.

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Objective: The aim of the present study was to examine the effect of degree of temporal processing impairment in adult listeners with ANSD on speech perception measures. Study design: Forty-six listeners with ANSD and 30 normal hearing listeners participated in the study. Temporal resolution was measured using the Temporal Modulation Transfer Function (TMTF). Speech identification scores in quiet were measured for bisyllabic words and Speech Reception Threshold in noise (SRTn) was measured for words. Furthermore, consonant identification was measured for 20 VCV stimuli. Results: Listeners with ANSD performed significantly worse than normal hearing listeners in both temporal resolution and speech perception measures. Peak sensitivity and 3dB cut-off frequency were estimated for each individual in both groups from the TMTFs data using an exponential fitting function. The listeners with ANSD were subgrouped into mild, moderate and severe degrees based on peak sensitivity. As the degree of temporal processing impairment increased, speech identification scores reduced and SRTn increased systematically. Similarly, consonant identification decreased with increase in temporal processing impairment. Among phonemic features, manner of articulation was better perceived compared to voice and place of articulation. Conclusion: The high correlation between temporal processing ability and speech perception suggests that temporal processing measures may be a potential tool for assessing the severity of ANSD in adult listeners.