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A fundamental question in the study of speech is about the invariance of the ultimate percepts, or features. The present paper gives an overview of the noninvariance problem and offers some hints towards a solution. Examination of various data on place and voicing perception suggests the following points. Features correspond to natural boundaries between sounds, which are included in the infant's predispositions for speech perception. Adult percepts arise from couplings and contextual interactions between features. Both couplings and interactions contribute to invariance. But this is at the expense of profound qualitative changes in perceptual boundaries implying that features are neither independently nor invariantly perceived. The question then is to understand the principles which guide feature couplings and interactions during perceptual development. The answer might reside in the fact that: (1) adult boundaries converge to a single point of the perceptual space, suggesting a context-free central reference; (2) this point corresponds to the neutral vocoïd, suggesting the reference is related to production; (3) at this point perceptual boundaries correspond to the natural ones, suggesting the reference is anchored in predispositions for feature perception. In sum, perceptual invariance seems to be grounded on a radial representation of the vocal tract around a singular point at which boundaries are context-fee, natural and coincide with the neutral vocoïd.
This paper summarizes our research efforts in functional modelling of the relationship between the acoustic properties of vowels and perceived vowel quality. Our model is trained on 164 short steady-state stimuli. We measured F1, F2, and additionally F0 since the effect of F0 on perceptual vowel height is evident. 40 phonetically skilled subjects judged vowel quality using the Cardinal Vowel diagram. The main focus is on refining the model and describing its transformation properties between the F1/F2 formant chart and the Cardinal Vowel diagram. An evaluation of the model based on 48 additional vowels showed the generalizability of the model and confirmed that it predicts perceived vowel quality with sufficient accuracy.
While the perilinguistic child is endowed with predispositions for the categorical perception of phonetic features, their adaptation to the native language results from a long evolution from the end of the first year of age up to the adolescence. This evolution entails both a better discrimination between phonological categories, a concomitant reduction of the discrimination between within-category variants, and a higher precision of perceptual boundaries between categories. The first objective of the present study was to assess the relative importance of these modifications by comparing the perceptual performances of a group of 11 children, aged from 8 to 11 years, with those of their mothers. Our second objective was to explore the functional implications of categorical perception by comparing the performances of a group of 8 deaf children, equipped with a cochlear implant, with normal-hearing chronological age controls. The results showed that the categorical boundary was slightly more precise and that categorical perception was consistently larger in adults vs. normal-hearing children. Those among the deaf children who were able to discriminate minimal distinctions between syllables displayed categorical perception performances equivalent to those of normal-hearing controls. In conclusion, the late effect of age on the categorical perception of speech seems to be anchored in a fairly mature phonological system, as evidenced the fairly high precision of categorical boundaries in pre-adolescents. These late developments have functional implications for speech perception in difficult conditions as suggested by the relationship between categorical perception and speech intelligibility in cochlear implant children.
This special issue of the ZAS Papers in Linguistics contains a collection of papers of the French-German Thematic Summerschool on "Cognitive and physical models of speech production, and speech perception and of their interaction".
Organized by Susanne Fuchs (ZAS Berlin), Jonathan Harrington (IPdS Kiel), Pascal Perrier (ICP Grenoble) and Bernd Pompino-Marschall (HUB and ZAS Berlin) and funded by the German-French University in Saarbrücken this summerschool was held from September 19th till 24th 2004 at the coast of the Baltic Sea at the Heimvolkshochschule Lubmin (Germany) with 45 participants from Germany, France, Great Britain, Italy and Canada. The scientific program of this summerschool that is reprinted at the end of this volume included 11 key-note presentations by invited speakers, 21 oral presentations and a poster session (8 presentations). The names and addresses of all participants are also given in the back matter of this volume.
All participants was offered the opportunity to publish an extended version of their presentation in the ZAS Papers in Linguistics. All submitted papers underwent a review and an editing procedure by external experts and the organizers of the summerschool. As it is the case in a summerschool, papers present either works in progress, or works at a more advanced stage, or tutorials. They are ordered alphabetically by their first author's name, fortunately resulting in the fact that this special issue starts out with the paper that won the award as best pre-doctoral presentation, i.e. Sophie Dupont, Jérôme Aubin and Lucie Ménard with "A study of the McGurk effect in 4 and 5-year-old French Canadian children".