Several researchers undertake to develop compatible theoretical accounts of speech production, speech perception and phonological knowledge:
• Carol Fowler proposes a “direct realism” theory of speech perception: listeners perceive gestures not by means of a specialized decoder, as in the motor theory, but because information in the acoustic signal specifies the gestures that form it.
• Inspired by Turvey’s earlier work on “action theory,” Carol Fowler, Rubin, Remez, and Turvey propose a theory of speech production in which phonetic goals (such as closing the lips, raising the tongue or opening the vocal cords) are achieved by transient, special-purpose organizations of the articulators, termed “coordinative structures” or “synergies.”
• Scott Kelso and colleagues demonstrate functional synergies in speech gestures experimentally. When one articulator in a synergy is perturbed (when the jaw is tugged down, for instance, as the lips close to form /b/), other articulators (in this instance the lips) automatically compensate to achieve lip closure.
• Elliot Saltzman develops a dynamical systems theory of synergetic action and implements the theory as a working model of speech production, in which actions of the articulators are gestures that form and release constrictions in the vocal tract.
• Linguists Catherine Browman and Louis Goldstein develop the theory of “articulatory phonology,” in which gestures are the basic units of both phonetic action and phonological knowledge. The associated “linguistic gestural model” generates appropriately phased patterns of gesture for words in English. These “gestural scores,” assigned dynamic values by the Saltzman model, drive the articulatory synthesizer of Rubin and Mermelstein to produce intelligible speech.
Alvin Liberman and Mattingly revise and update the motor theory, recasting it in an explicitly bio logical frame. They posit a specialized “phonetic module,” encompassing both production and perception, analogous in some respects to modules for sound localization in the bat, the barn owl, and humans. The revised motor theory remains viable, though controversial, today.
Giuseppe Cossu, Isabelle Liberman, and Shankweiler are among the first to present evidence that difficulties in acquiring phoneme awareness and ensuing problems in word recognition characterize reading disability across different languages that use an alphabet.
Shankweiler, Stephen Crain, Mann, and Paul Macaruso present evidence that language comprehension difficulties associated with reading disability are typically based on processing limitations, not deficiencies of grammatical knowledge.
Bell-Berti shows that vocal tract configurations underlying a given phonological contrast (consonant voicing, for instance) entail active (or passive) engagement of all the articulators, not only those effecting the contrast.
Borden and Harris publish Speech Science Primer, a graduate and advanced undergraduate introduction to speech science. First published in 1980 and later revised in collaboration with Lawrence Raphael, the book is now in its fourth edition.