Peñ a, Bonatti, Nespor, and Mehler (2002) investigated an artificial language where the structure of words was determined by nonadjacent dependencies between syllables. They found that segmentation of continuous speech could proceed on the basis of these dependencies. However, Peñ a et al.Õs artificial language contained a confound in terms of phonology, in that the dependent syllables began with plosives and the intervening syllables began with continuants. We consider three hypotheses concerning the role of phonology in speech segmentation in this task: (1) participants may recruit probabilistic phonotactic information from their native language to the artificial language learning task;(2) phonetic properties of the stimuli, such as the gaps that precede unvoiced plosives, can influences segmentation; and (3) grouping by phonological similarity between dependent syllables contributes to learning the dependency. In a series of experiments controlling the phonological and statistical structure of the language, we found that segmentation performance is influenced by the three factors in different degrees. Learning of nonadjacent dependencies did not occur when (3) is eliminated. We suggest that phonological processing provides a fundamental contribution to distributional analysis.

Although much is known about how speech is produced, and research into speech production has resulted in measured articulatory data, feature systems of different kinds and numerous models, speech production knowledge is almost totally ignored in current mainstream approaches to automatic speech recognition. Representations of speech production allow simple explanations for many phenomena observed in speech which cannot be easily analyzed from either acoustic signal or phonetic transcription alone. In this article, we provide a survey of a growing body of work in which such representations are used to improve automatic speech recognition.PACS numbers: 43.72.Ne (Automatic speech recognition systems); 43.70.Jt (Instrumentation and methodology for speech production research); 43.70.Bk (Models and theories of speech production)

Abstract-This paper presents an investigation into ways of integrating articulatory features into hidden Markov model (HMM)-based parametric speech synthesis. In broad terms, this may be achieved by estimating the joint distribution of acoustic and articulatory features during training. This may in turn be used in conjunction with a maximum-likelihood criterion to produce acoustic synthesis parameters for generating speech. Within this broad approach, we explore several variations that are possible in the construction of an HMM-based synthesis system which allow articulatory features to influence acoustic modeling: model clustering, state synchrony and cross-stream feature dependency. Performance is evaluated using the RMS error of generated acoustic parameters as well as formal listening tests. Our results show that the accuracy of acoustic parameter prediction and the naturalness of synthesized speech can be improved when shared clustering and asynchronous-state model structures are adopted for combined acoustic and articulatory features. Most significantly, however, our experiments demonstrate that modeling the dependency between these two feature streams can make speech synthesis systems more flexible. The characteristics of synthetic speech can be easily controlled by modifying generated articulatory features as part of the process of producing acoustic synthesis parameters.

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We have previously proposed a trajectory model which is based on a mixture density network (MDN) trained with target variables augmented with dynamic features together with an algorithm for estimating maximum likelihood trajectories which respects the constraints between those features. In this paper, we have extended that model to allow diagonal covariance matrices and multiple mixture components in the trajectory MDN output probability density functions. We have evaluated this extended model on an inversion mapping task and found the trajectory model works well, outperforming smoothing of equivalent trajectories using low-pass filtering. Increasing the number of mixture components in the TMDN improves results further.