Bilingual Listeners' Perception of Temporally Manipulated English Passages

Abstract

Purpose The current study measured, objectively and subjectively, how changes in speech rate affect recognition of English passages in bilingual listeners. Method Ten native monolingual, 20 English-dominant bilingual, and 20 non-English-dominant bilingual listeners repeated target words in English passages at five speech rates (unprocessed, two expanded, and two compressed), in quiet and in noise. For noise conditions, performance was measured at a signal-to-noise ratio that was determined through an adaptive procedure to avoid ceiling and floor effects. Listeners also made subjective judgments of speech rate, speech clarity, and performance confidence. Results In noise, stepwise improvement was observed as rate slowed down. A similar effect was not found in quiet. This pattern in performance was largely comparable across listener groups but was most robust in English-dominant listeners. Changes in speech rate and presence of noise significantly affected listeners' subjective ratings; however, no intergroup differences were observed for any of the subjective ratings. Conclusions Bilingual listeners benefited from slow speech rates, more evidently so in noise than in quiet. Their performance, however, did not reach a monolingual level, even at the most favorable rate. Nonetheless, all listeners reported comparable confidence when processing temporally manipulated English passages.