Speech rhythm and speech rate affect segmentation of reduced function words in continuous speech

Recent work (Dilley & Pitt, 2010, Psychological Science) has demonstrated that reduced function words in speech can perceptually disappear if the rate of surrounding speech is slowed, even when the acoustic properties of the function word (FW) and its immediate phonetic environment are held constant. An experiment was therefore conducted to determine whether this disappearing word effect could be elicited through a manipulation involving speech rhythm, realized as binary and ternary alternations of high and low tones, as well as through manipulations to context speech rate. 74 participants transcribed 32 sentences containing a FW in which the preceding speech within the utterance was resynthesized with a binary or ternary speech rhythm presented at one of three context speech rates. A binary rhythm in the preceding speech context yielded lower FW report rates than the ternary rhythm. These results suggest that listeners' expectations about speech rhythm and/or syllable grouping affected the number of syllables and words perceived, indicating that such properties may play an important role in word segmentation and lexical access. Work supported by NSF grant BCS-0847653.