Standardizing calibration procedures is unlikely to decrease the analytical variability of creatinine assays enough to allow uniform and reliable use of the equations for estimation of glomerular filtration rate.

An unavoidable problem in speech technology, particularly in the development of robust automatic speech recognition systems, is the extreme variability in the acoustic attributes of segments. Segments are highly sensitive to context and bear little resemblance to their intrinsic characteristics manifested when they are uttered in isolation. However, the problem can become tractable if we model the linguistic and physiological aspects of coarticulatory processes, the main source of systemic variability at the segmental level.

This work was aimed at exploring articulatory-acoustic relationships in the production of French fricatives. More precisely, an attempt was made to find out whether the spectral shapes of [s] and 10 can be regenerated from the x and y coordinates of three electromagnetic transducers affixed to the tongue in the midsagittal plane. The corpus was composed of the two fricatives Is/ and Is/ combined with the vowels /al and Ii/ in sequences of the type lVs~/ and /V@VI, and was read by one male native speaker of French. The spectrum regeneration was based on a statistical procedure which consisted of estimating the factors explaining the main part of the acoustic variance from the position of the transducers, by means of multiple linear regression. The articulatory-acoustic correlations were high and allowed us to regenerate the fricative spectra with a good accuracy. The way in which the acoustic parameters varied as a function of the articulatory ones in the statistical model was in good agreement with data reported in previous works. The results support the idea that the tongue has relatively few degrees of freedom in the production of [s] and 10.

Sequences of stops are often characterized by a dual closure. According to some authors C1 is released. Our articulatory data (electropalatography) confirm their acoustical findings. In the case of a front-to-back coarticulation, the release of C1 in French is similar to the production of a click.

Previous studies on lingual movements in speech have led to the assumption that the tongue can be divided into a small number of functional blocks. This work was aimed at nding out whether such a subdivision into independent components may also be observed in patterns of tongue-palate contacts, as revealed by electropalatography (EPG). An attempt was made to reduce EPG data to a small number of articulatorily relevant parameters in an empirical way, and to model the con guration of the linguo-palatal contacts in speech as a combination of these parameters. Our corpus was composed of ten natural sentences recorded by two female native speakers of French. EPG data reduction was performed by means of a feedforward multilayer neural network on the one hand, and of a factor analysis on the other hand.The results showed that variations in the tongue-palate contact pattern mainly occurred along two dimensions, related to lingual contacts in 1) the alveolar region and 2) the palatal region, respectively. These results were consistent for both subjects, and provided evidence for the hypothesis that the tongue tip/blade and the tongue dorsum are two independently controllable articulators. In a second step, potential applications of this empirical model to studies of coarticulation and timing are illustrated, through a pilot investigation of /kl/ clusters. Finally, implications of our work for a comprehensive model of tongue movements are discussed. Nguyen et al.Modeling tongue-palate contact patterns 2