Effect of context on bimodal benefit for temporally interrupted sentences in simulated electric-acoustic stimulation

Abstract

Previous research has demonstrated a clear effect of linguistic context on bimodal benefit for continuous speech, implicating an interaction between low-frequency acoustic cues and top-down linguistic processing (Kong et al., CIAP 2013). However, bimodal benefit appears to be reduced for phonemic restoration (Baskent, 2012 JARO), suggesting that low-frequency facilitation of top-down processing is weakened when the speech stream is interrupted. The present study examined top-down effects in temporally interrupted speech by comparing bimodal benefit for low- and high-context sentences. Young, normal-hearing listeners were presented with City University of New York (CUNY) or Institute of Electrical and Electronics and Engineers (IEEE) sentences that were gated with silence (5 Hz, 50% duty cycle). One ear received sentences that were noise-band vocoded (8, 12, or 16 channels for CUNY; 12, 16, or 32 channels for IEEE) and the other ear received low-pass (LP) speech or LP harmonic complexes (LPHCs). Findings demonstrated clear effects of context on bimodal benefit when LP speech was presented to the residual-hearing ear, however, the benefits observed were considerably smaller than those reported previously for continuous speech. Unlike previous findings for continuous speech, no bimodal benefits were observed when LPHCs were presented to the LP ear.