Pascal Perrier

Influences of tongue biomechanics on speech movements during the production of velar stop consonants: A modeling study

This study explores the following hypothesis: forward looping movements of the tongue that are observed in VCV sequences are due partly to the anatomical arrangement of the tongue muscles, how they are used to produce a velar closure, and how the tongue interacts with the palate during consonantal closure. The study uses an anatomically based two-dimensional biomechanical tongue model. Tissue elastic properties are accounted for in finite-element modeling, and movement is controlled by constant-rate control parameter shifts. Tongue raising and lowering movements are produced by the model mainly with the combined actions of the genioglossus, styloglossus, and hyoglossus. Simulations of V1CV2 movements were made, where C is a velar consonant and V is [a], [i], or [u]. Both vowels and consonants are specified in terms of targets, but for the consonant the target is virtual, and cannot be reached because it is beyond the surface of the palate. If V1 is the vowel [a] or [u], the resulting trajectory describes a movement that begins to loop forward before consonant closure and continues to slide along the palate during the closure. This pattern is very stable when moderate changes are made to the specification of the target consonant location and agrees with data published in the literature. If V1 is the vowel [i], looping patterns are also observed, but their orientation was quite sensitive to small changes in the location of the consonant target. These findings also agree with patterns of variability observed in measurements from human speakers, but they contradict data published by Houde [Ph.D. dissertation (1967)]. These observations support the idea that the biomechanical properties of the tongue could be the main factor responsible for the forward loops when V1 is a back vowel, regardless of whether V2 is a back vowel or a front vowel. In the [i] context it seems that additional factors have to be taken into consideration in order to explain the observations made on some speakers.

Correlation between angle of incidence and sliding patterns of the tongue along the palate in Korean velar stops

In former studies, it has been hypothesized that the articulatory production of oral stops could result from the interaction between the tongue moving towards a virtual target located above the palate, and the palate. Velar stops, where the tongue slides along the palate during the occlusion phase, offer a nice experimental framework for further experimental assessments. Indeed, in the framework of the ‘‘virtual target’’ hypothesis, the sliding movement should be seen as the continuation of the movement before the occlusion, but constrained by the palate. Hence, relations should exist between the movement characteristics before contact and during the occlusion phase. To test this hypothesis three Korean speakers were recorded via EMA producing /aCV/ sequences with C=/g/, /k’/ and /kh/, V=/a/, /i/ or /u/. The angle between tongue trajectory just before the impact and palatal contour was estimated, and the amplitude of the sliding movement was measured. Preliminary results for two speakers show that these t...

Use of a Biomedicanical Tongue Model to Predict the Impact of Tongue Surgery on Speech Production

This paper presents predictions of the consequences of tongue surgery on speech production. For this purpose, a 3D finite element model of the tongue is used that represents this articulator as a deformable structure in which tongue muscles anatomy is realistically described. Two examples of tongue surgery, which are common in the treatment of cancers of the oral cavity, are modelled, namely a hemiglossectomy and a large resection of the mouth floor. In both cases, three kinds of possible reconstruction are simulated, assuming flaps with different stiffness. Predictions are computed for the cardinal vowels /i, a, u/ in the absence of any compensatory strategy, i.e. with the same motor commands as the one associated with the production of these vowels in non-pathological conditions. The estimated vocal tract area functions and the corresponding formants are compared to the ones obtained under normal conditions