Chris Heffner · [HESP Seminar] Differences in Timing Perception Due to Aging May Not Entail Differences in Timing Use
Listeners face many challenges in deciding how to interpret speech. One of these challenges is word segmentation, that is, figuring out where one word ends and the next begins in fluent speech. Listeners use a variety of information when deciding how to segment words. For example, listeners rely on information about how fast someone is talking at the beginning of a sentence to make inferences about how to segment words later in a sentence (Dilley & Pitt, 2010). Here, we compare the strength of what have been termed “distal speech rate effects” to context cues from syntax in older adults (55-65 years old). Younger adults are more strongly influenced by distal speech rate effects than the particular syntactic context cues used here, but we predicted that older adults, whose changes in temporal perception of speech are well-documented, may rely more on syntactic cues.
The results did not match our predictions. Instead, surprisingly, 55-to-65-year-old adults are largely indistinguishable from younger adults in their word segmentation preferences. Neither a main effect of age nor interactions between age and distal speech rate effects or syntactic context effects were observed, even despite the high-frequency hearing loss present in some of the older adults. From a follow-up study, it does not appear that these null effects are the result of stimulus properties, as we are successfully replicating previous experiments (e.g., Gordon-Salant & Fitzgibbons, 2001) showing age-related effects on comprehension of compressed sentences. Instead, it seemed to be the case that differences in rate-related perception do not entail differences in rate-related use.