A motor theory of speech perception, initially proposed to account for results of early experiments with synthetic speech, is now extensively revised to accommodate recent findings, and to relate the assumptions of the theory to those that might be made about other perceptual modes. According to the revised theory, phonetic information is perceived in a biologically distinct system, a ‘module ’ specialized to detect the intended gestures of the speaker that are the basis for phonetic categories. Built into the structure of this module is the unique but lawful relationship between the gestures and the acoustic patterns in which they are variously overlapped. In consequence, the module causes perception of phonetic structure without translation from preliminary auditory impressions. Thus, it is comparable to such other modules as the one that enables an animal to localize sound. Peculiar to the phonetic module are the relation between perception and production it incorporates and the fact that it must compete with other modules for the same stimulus variations.

This article describes a neural network model of speech motor skill acquisition and speech production that explains a wide range of data on variability, motor equivalence, coarticulation, and rate effects. Model parameters are learned during a babbling phase. To explain how infants learn language-specific variability limits, speech sound targets take the form of convex regions, rather than points, in orosensory coordinates. Reducing target size for better accuracy during slower speech leads to differential effects for vowels and consonants, as seen in experiments previously used as evidence for separate control processes for the 2 sound types. Anticipatory coarticulation arises when targets are reduced in size on the basis of context; this generalizes the well-known look-ahead model of coarticulation. Computer simulations verify the model's properties. The primary goal of the modeling work described in this article is to provide a coherent theoretical framework that provides explanations for a wide range of data concerning the articulator movements used by humans to produce speech sounds. This is carried out by formulating a model that transforms strings of phonemes into continuous articulator movements for

Footnote This article is based on a February, 1992workshop sponsored by the National Science

Much sensory-motor behavior develops through imitation, as during the learning of handwriting by children. Such complex sequential acts are broken down into distinct motor control synergies, or muscle groups, whose activities overlap in time to generate continuous, curved movements that obey an inverse relation between curvature and speed. How are such complex movements learned through attentive imitation? Novel movements may be made as a series of distinct segments, but a practiced movement can be made smoothly, with a continuous, often bellshaped, velocity profile. How does learning of complex movements transform reactive imitation into predictive, automatic performance? A neural model is developed which suggests how parietal and motor cortical mechanisms, such as difference vector encoding, interact with adaptively-timed, predictive cerebellar learning during movement imitation and predictive performance. To initiate movement, visual attention shifts along the shape to be imitated an...

this paper I re-examine the case for distinguishing language-specific phonetics from phonology, and concludes that this move is unmotivated. It is feasible to account for 4 phonetic and phonological phenomena within a unified framework, and such a model is better able to account for the many similarities between phonetics and phonology. It is appropriate to distinguish components of grammar where the representations and principles operative in each component are fundamentally distinct, thus it is uncontroversial to distinguish phonology from syntax. It is difficult to justify a distinction between phonetics and phonology on these grounds. Phonetics and phonology are not obviously distinguished by the nature of the representations involved, or in terms of the phenomena they encompass. As far as representation is concerned, most of the primitives of phonological representation remain phonetically-based in the sense that features and timing units are provided with broadly phonetic definitions. This has the peculiar consequence that sound is represented twice in grammar: Once at a coarse level of detail in the phonology, and then again at a finer grain in the phonetics. Perhaps more significant is the fact that there are also substantial similarities between many phenomena which are conventionally classified as phonetic and those which are conventionally classified as phonological, for example coarticulation is similar in many respects to assimilation. The aim of this paper is to explore the idea that these parallels are best accounted for by analyzing both `phonetic' and `phonological' phenomena within a unified framework so the similar properties of the two can be derived from the same constraints. Unifying phonetics and phonology does not imply a denial of the distinct...

understanding

A geometric and kinematic model for describing the global shape and the predominant motions of the human tongue, to be applied in computer animation, is discussed. The model consists of a spatial configuration of moving points that form the vertices of a mesh of 9 3-D triangles. These triangles are interpreted as charge centres (the so-called skeleton) for a potential field, and the surface of the tongue is modelled as an equi-potential surface of this field. In turn, this surface is approximated by a triangular mesh prior to rendering. As to the motion of the skeleton, precautions are taken in order to achieve (approximate) volume conservation; the computation of the triangular mesh describing the surface of the tongue implements penetration avoidance with respect to the palate. Further, the motions of the skeleton derive from a formal speech model which also controls the motion of the lips to arrive at a visually plausible speech synchronous mouth model. 1

This report describes the key research topics, the expected benefits of the research, and recommendations to NSF on the infrastructure needed to support the research.

Detailed study of data in Dixon's (1977) grammar indicates that previous analyses of Yidi# have erred in supposing that the synchronic pattern of the language continues the historical pattern, whereby various nominal stems have their underlying final vowels deleted when no suffix follows. Instead, it appears that the system has undergone a radical reanalysis, whereby the suffixed forms are now projectable by general principles from the isolation forms. More precisely, a pattern of multiple predictability has developed: the form of suffixed allomorphs is largely predictable from the isolation allomorphs, but the older pattern, whereby isolation allomorphs can be predicted from the suffixed allomorphs, also persists. From this descriptive result, three principal theoretical consequences are developed: (a) Yidi# possesses a fully-productive pattern of alternation that is not driven by markedness-faithfulness interactions; (b) the phonological constraints that are active in Yidi# likely include some that are quite unlikely to be members of a universal inventory; (c) there are more relations of predictability among surface forms in Yidi# than can be treated by the normal method, namely that of deriving all the surface allomorphs from a single underlying representation. A tentative suggestion is made for how Optimality Theory might be extended to treat cases of this sort, by means of a class of "Anticorrespondence" constraints. Phonological Restructuring in Yidi# and its Theoretical Consequences 1.

this paper. 3. uppu: Through the hoop a poodle jumped 4. *tt*: They are going to fit a timber roof on our house. 5. aettae: We gave the cat a tag to wear round its neck. 6. uttu: The robbers went to loot a tomb. 7. *kk*: You may pick a kitten from the basket. 8. aekkae: I forgot to pack a can of coffee for him. 9. ukku: I gave Luke a cool drink. 2.2 Results