Environmental Sound Perception with Amplitude and Frequency Modulations in Simulated Cochlear Implant

Objective: The present study investigated the effect of frequency modulation and amplitude modulation on perception of environmental sounds of different categories in the acoustic simulation of cochlear implant. Materials and Methods: The participants were fifteen graduate students of age ranging from 19 to 26 years with normal hearing sensitivity. Five categories of environmental stimuli important in everyday life were used (nature, mechanical/alerting, vehicles human and animals). These sounds were processed with a Frequency-Amplitude-Modulation-Encoding strategy, implemented in Mat lab. The stimulus presentation and response acquisition were controlled via 'DMDX' software. Results: Two way repeated measure ANOVA showed a significant difference between frequency modulation plus amplitude modulation and amplitude modulation conditions. A significant difference was seen within-subjects for different categories and significant interaction was seen between conditions & category. Conclusions: Good scores on frequency modulation plus amplitude modulation condition emphasis the importance of FM cues. Hence future speech processing strategies for cochlear implants to focus on implementing fine structure cue which may facilitate the identification of environmental sounds. The present method can be used in the evaluation of Cochear Implantees performance on perception of environmental sound which is an important component of post implant auditory rehabilitation.