On recognizing spectrally reduced speech by multiple talkers: A cochlear implant simulation study

Abstract

In a previous study [Loizou et al., J. Acoust. Soc. Am. 106, 2097–2103 (1999)], normal-hearing listeners identified sentences from the multitalker sentence set TIMIT that were spectrally reduced using the CIS processing strategy [Shannon et al., J. Acoust. Soc. Am. 104, 2467–2476 (1998)]. It was reported that listeners could achieve open-set sentence recognition (90%) with as few as five channels, with asymptotic performance achieved with eight channels. Such results were compared with another study [Dorman et al., J. Acoust. Soc. Am. 102, 2403–2411 (1997)] using different sentences from the single-talker HINT set, where asymptotic performance was achieved with four channels. The present study directly compares identification for spectrally reduced TIMIT sentences spoken by a male talker, by a female talker, and by multiple talkers. Separate groups of subjects with normal hearing served in these three conditions. The design therefore controlled potential differences in the lexical, syntactic, and semantic aspects of the materials in TIMIT versus HINT that could have accounted for the above findings. Results will be discussed in terms of theories of auditory memory and speech perception.