Effect of relative timing of target and background words on speech understanding using the coordinate response measure paradigm

Abstract

Recognition of target keywords in CRM sentences in the presence of competing CRM sentences has been shown to depend upon both the rhythmic context of target and background speech and F0 differences between target and background speakers. The present study investigated the role of the relative timing of target and background keywords for background keywords that were presented either in isolation (Experiment 1) or embedded within their associated background context (Experiment 2) for target and background material that was spoken by the same male talker. In Experiment 1, onset asynchrony of target and background keywords varied between –200 ms and 200 ms. Results showed an asymmetric U-shaped performance curve where (1) target recognition improved with increasing deviation of background keywords from the expected onset timing of target keywords and (2) target words were better recognized when they began before background keywords compared to when they began after. In Experiment 2, where background keywords were embedded within their original CRM context, performance was reduced to chance for both an intact background rhythm condition and a range of altered background rhythm conditions. Results will be discussed in terms of a selective entrainment hypothesis and the role of F0 differences in speech segregation.