A portable, real-time vocoder: Technology and preliminary perceptual learning findings.

Abstract

Transformed or vocoded acoustic signals paralleling the processing of cochlear implants have proven extremely useful for simulating aural perception in deaf CI users with normal hearing participants. The benefits of current perceptual studies with vocoded stimuli are limited, however, in their ecological validity and direct applicability to the everyday challenges faced by CI users. Normal hearing subjects listen for relatively short periods of time to isolated, prerecorded words or sentences; therefore, their perceptual learning occurs without the semantic context, visual support, and conversational interplay that normally accompanies spoken language use. In this paper, the development of a new device, which enables vocoded speech research to overcome many of these limitations, is described. This technology carries out vocoding signal transformations in real-time, with very short delays, and is small enough to fit in a participant’s pocket. The portable, real-time vocoder (PRTV) therefore allows subjects to experience vocoded acoustics while freely interacting with their environment and the people in it, potentially for extended periods of time. Preliminary investigation of perceptual learning with the PRTV has demonstrated its efficacy: improvements of up to 15% in open-set word recognition accuracy were found in 3 NH listeners after 1.5 h of interactive use.