Quantal biomechanics in an embodied phonetics

Quantal regions were described by Stevens [e.g., 1989, J. Phon. 17, 3–45] to identify nonlinear stabilities in the relationship between articulation and acoustics. Classic cases of quantal effects show how tongue posture may vary within one region of the vocal tract with little acoustic change, while in other regions very small movements can have large effects on acoustic output. Such effects can be thought of as attractors to speech behavior in those regions of the phonetic space that allow greater noise. Quantal-like stabilities have been suggested to operate not just in articulatory-acoustic space, but in biomechanical-articulatory space as well [e.g., Schwartz et al., 1997, J. Phon. 25, 255–286]. It is argued here that such quantal-like stabilities are a hallmark of speech modules [Gick & Stavness, 2013, Front. Psych. 4, 977], providing the basis for robust, feed-forward control. Computer simulations in the ArtiSynth platform (www.artisynth.org) are used to demonstrate quantal effects in speech biomechanics at multiple vocal tract loci, including the lips, oropharyngeal isthmus, and larynx. Moving into the future, quantal work will integrate observations about nonlinear stabilities cutting across the many physical and sensory domains that figure in speech. [Research funded by NSERC.]