The Unsupervised Acquisition of a Lexicon from Continuous Speech

We present an unsupervised learning algorithm that acquires a natural-language lexicon from raw speech. The algorithm is based on the optimal encoding of symbol sequences in an MDL framework, and uses a hierarchical representation of language that overcomes many of the problems that have stymied previous grammar-induction procedures. The forward mapping from symbol sequences to the speech stream is modeled using features based on articulatory gestures. We present results on the acquisition of lexicons and language models from raw speech, text, and phonetic transcripts, and demonstrate that our algorithm compares very favorably to other reported results with respect to segmentation performance and statistical efficiency.Comment: 27 page technical repor

The Status of Coronals in Standard American English . An Optimality-Theoretic Account

Coronals are very special sound segments. There is abundant evidence from various fields of phonetics which clearly establishes coronals as a class of consonants appropriate for phonological analysis. The set of coronals is stable across varieties of English unlike other consonant types, e.g. labials and dorsals, which are subject to a greater or lesser degree of variation. Coronals exhibit stability in inventories crosslinguistically, but they simultaneously display flexibility in alternations, i.e. assimilation, deletion, epenthesis, and dissimilation, when it is required by the contradictory forces of perception and production. The two main, opposing types of alternation that coronals in SAE participate in are examined. These are weakening phenomena, i.e. assimilation and deletion, and strengthening phenomena, i.e. epenthesis and dissimilation. Coronals are notorious for their contradictory behavior, especially in alternations. This type of behavior can be accounted for within a phonetically grounded OT framework that unites both phonetic and phonological aspects of alternations. Various sets of inherently conflicting FAITHFULNESS and MARKEDNESS constraints that are needed for an OT analysis of SAE alternations are intoduced

‘Voice’ languages with no [voice]? Some consequences of Laryngeal Relativism

Strict criteria on phonological categoryhood coupled with strict privativity of representation inevitably lead to a conclusion that sonorants must not contain a prime responsible for voicing. Assuming that this prime is also not supplied to sonorants in the course of phonological derivation, this class of segments, contrary to observed patterns, should be inactive with respect to voicing phenomena. Presonorant sandhi voicing in Cracow-Poznań Polish is used to show how such apparent patterns can be dealt with without compromising the above theoretical assumptions. This however has consequences which bear on almost every aspect of laryngeal phonology. Some of them include: arbitrariness of the relation between phonology and phonetics, emergent nature of laryngeal categories, minimization of the role of phonological computation, re-evaluation of typical analytical criteria for deciding on phonological representation of laryngeal distinctions, which are used in phonological practice, as well as a possibility that the prime [voice], or its theoretical counterpart in various models, is not present in some ‘voice’ languages

The evolution of auditory contrast

This paper reconciles the standpoint that language users do not aim at improving their sound systems with the observation that languages seem to improve their sound systems. Computer simulations of inventories of sibilants show that Optimality-Theoretic learners who optimize their perception grammars automatically introduce a so-called prototype effect, i.e. the phenomenon that the learner’s preferred auditory realization of a certain phonological category is more peripheral than the average auditory realization of this category in her language environment. In production, however, this prototype effect is counteracted by an articulatory effect that limits the auditory form to something that is not too difficult to pronounce. If the prototype effect and the articulatory effect are of a different size, the learner must end up with an auditorily different sound system from that of her language environment. The computer simulations show that, independently of the initial auditory sound system, a stable equilibrium is reached within a small number of generations. In this stable state, the dispersion of the sibilants of the language strikes an optimal balance between articulatory ease and auditory contrast. The important point is that this is derived within a model without any goal-oriented elements such as dispersion constraints

On The Linguistic Effects Of Articulatory Ease, With A Focus On Sign Languages

Spoken language has a well-known drive for ease of articulation, which Kirchner (1998, 2004) analyzes as reduction of the total magnitude of all biomechanical forces involved. We extend Kirchner\u27s insights from vocal articulation to manual articulation, with a focus on joint usage, and we discuss ways that articulatory ease might be realized in sign languages. In particular, moving more joints and/or joints more proximal to the torso results in greater mass being moved, and thus more articulatory force being expended, than moving fewer joints or moving more distal joints. We predict that in casual conversation, where articulatory ease is prized, moving fewer joints should be favored over moving more, and moving distal joints should be favored over moving proximal joints. We report on the results of our study of the casual signing of fluent signers of American Sign Language, which confirm our predictions: in comparison to citation forms of signs, the casual variants produced by the signers in our experiment exhibit an overall decrease in average joint usage, as well as a general preference for more distal articulation than is used in citation form. We conclude that all language, regardless of modality, is shaped by a fundamental drive for ease of articulation. Our work advances a cross-modality approach for considering ease of articulation, develops a potentially important vocabulary for describing variations in signs, and demonstrates that American Sign Language exhibits variation that can be accounted for in terms of ease of articulation. We further suggest that the linguistic drive for ease of articulation is part of a broader tendency for the human body to reduce biomechanical effort in all physical activities

Emergence of articulatory-acoustic systems from deictic interaction games in a "vocalize to localize" framework

International audienceSince the 70's and Lindblom's proposal to "derive language from non-language", phoneticians have developed a number of "substance-based" theories. The starting point is Lindblom's Dispersion Theory and Stevens's Quantal Theory, which open the way to a rich tradition of works attempting to determine and possibly model how phonological systems could be shaped by the perceptuo-motor substance of speech communication. These works search to derive the shapes of human languages from constraints arising from perceptual (auditory and perhaps visual) and motor (articulatory and cognitive) properties of the speech communication system: we call them "Morphogenesis Theories". More recently, a number of proposals were introduced in order to connect pre-linguistic primate abilities (such as vocalization, gestures, mastication or deixis) to human language. For instance, in the "Vocalize-to-Localize" framework that we adopt in the present work (Abry & al., 2004), human language is supposed to derive from a precursor deictic function, considering that language could have provided at the beginning an evolutionary development of the ability to "show with the voice". We call this type of theories "Origins Theories". We propose that the principles of Morphogenesis Theories (such as dispersion principles or the quantal nature of speech) can be incorporated and to a certain extent derived from Origins Theories. While Morphogenesis Theories raise questions such as "why are vowel systems shaped the way they are?" and answer that it is to increase auditory dispersion in order to prevent confusion between them, we ask questions such as "why do humans attempt to prevent confusion between percepts?" and answer that it could be to "show with the voice", that is, to improve the pre-linguistic deictic function. In this paper, we present a computational Bayesian model incorporating the Dispersion and Quantal Theories of speech sounds inside the Vocalize-to-Localize framework, and show how realistic simulations of vowel systems can emerge from this model