White, L. .
Newcastle University, UK
Interpretation of temporally-encoded information in speech appears to necessitate the use of predictive mechanisms. To recognise a durational cue, such as the lengthening associated with geminate consonants or stressed syllables, listeners are required to perceive sounds as longer than expected based on foregoing speech rate. Indeed, rate variation can change listeners' interpretation of target sounds whose actual duration remains fixed: with a faster foregoing rate, for example, one syllable can be heard as two (Dilley & Pitt, 2010) or perceived word boundary location can change (Reinisch, Jesse & McQueen, 2011).
The latter finding indicates that temporal variation is an important source of information about linguistic structure as well as segmental identity. Notably, lengthening of vowels before phrase and utterance boundaries is proposed to be a potentially universal structural cue (e.g., Tyler & Cutler, 2009). In a cross-linguistic perceptual study we show, however, that whilst English listeners do perceive lengthened vowels as indicating an upcoming boundary, Hungarian and Italian listeners do not exploit this cue in the absence of other prosodic markers, despite its ubiquity in speech production.
By contrast, word-initial lengthening of consonants is perceived by all listeners - Italian, Hungarian and English - as indicating a preceding boundary. This is despite Hungarian and Italian use of consonant duration as a phonemic length cue. We propose that the power of initial lengthening relates to the exploitation of perceptuomotor analogies in a predictive fashion by listeners. Given general principles of motor control and planning, listeners have an expectation that speech should gradually accelerate and decelerate at the edges of linguistic units. We further hypothesis that constraints on the parallel exploitation of timing for other linguistic purposes explains cross-linguistic variation in the perception of preboundary vowel lengthening, whilst initial consonant lengthening appears to be a universal cue to word boundaries.