(This is a joint work with James Kirby, as part of the ERC-funded EVOTONE project.)

Coarticulation constitutes one source of variation in speech, which may give rise to sound change. Beddor’s « coarticulatory path to sound change » model (Beddor 2009) postulates that a subset of sound changes arise from the reinterpretation of a cue as being associated to the effect of coarticulation rather than to the source of it. Crucially, prior to this reinterpretation, the coarticulatory source trades with its effect: The source and the effect (1) compensate each other in production, and (2) are perceived as equivalent. Beddor’s model was developed based on the ongoing phonologisation of vowel nasalisation in American English, but she suggested it may also apply to other sound changes including tonogenesis stemming from onset voicing.
Our project in progress investigates the synchronic pattern of coarticulation between onset voicing and F0 in French, where obstruent-intrinsic F0 perturbations (or CF0) are not phonologised. We conducted a series of acoustic and perception studies to explore the trading relation between the source (prevoicing) and the effect (CF0). In production, we failed to find such a trading relation. Rather, for most speakers, the length of voice lead correlates positively with the lowering of F0, rather than trading with it. In perception, we addressed the question of perceptual equivalence for lower-level vs. higher-level perception, using three tasks: AX discrimination, 2AFC identification, and identification on a continuous scale. Our interim findings do not support a default trading relation. Rather, across listeners, higher discriminability of VOT predicts higher discriminability of F0. However, listeners who show higher discriminability of F0 also show higher perceptual equivalence when VOT is ambiguous, but lower perceptual equivalence when VOT is unambiguous. Unlike vowel nasalisation, listeners’ grammars do not differ in how they weight VOT and F0 perceptually, but whether and how they integrate F0 as a cue to voicing and/or perceive it as a non-phonemic feature when VOT becomes unreliable. We speculate that CF0 phonologisation is not initiated by a listener-specific grammar based on cue weighting, but by a shift in attention to a secondary cue when the primary cue is ambiguous by listeners who have stronger cue integration.

Reference:
Beddor, P. S. (2009). A coarticulatory path to sound change. Language, 785-821.