Coupling relations underlying the production of speech articulator movements and their invariance to speech rate.

Since the seminal works of Bernstein (The coordination and regulation of movements. Pergamon Press, Oxford, 1967) several authors have supported the idea that, to produce a goal-oriented movement in general, and a movement of the organs responsible for the production of speech sounds in particular, individuals activate a set of coupling relations that coordinate the behavior of the elements of the motor system involved in the production of the target movement or sound. In order to characterize the configurations of the coupling relations underlying speech production articulator movements, we introduce an original method based on recurrence analysis. The method is validated through the analysis of simulated dynamical systems adapted to reproduce the features of speech gesture kinematics and it is applied to the analysis of speech articulator movements recorded in five German speakers during the production of labial and coronal plosive and fricative consonants at variable speech rates. We were able to show that the underlying coupling relations change systematically between labial and coronal consonants, but are not affected by speech rate, despite the presence of qualitative changes observed in the trajectory of the jaw at fast speech rate.

Automatic quantitative analysis of ultrasound tongue contours via wavelet-based functional mixed models.

This paper illustrates the application of wavelet-based functional mixed models to automatic quantification of differences between tongue contours obtained through ultrasound imaging. The reliability of this method is demonstrated through the analysis of tongue positions recorded from a female and a male speaker at the onset of the vowels /a/ and /i/ produced in the context of the consonants /t/ and /k/. The proposed method allows detection of significant differences between configurations of the articulators that are visible in ultrasound images during the production of different speech gestures and is compatible with statistical designs containing both fixed and random terms.

Inter-speaker articulatory variability during vowel-consonant-vowel sequences in twins and unrelated speakers.

The purpose of this study is to examine and compare the amount of inter-speaker variability in the articulation of monozygotic twin pairs (MZ), dizygotic twin pairs (DZ), and pairs of unrelated twins with the goal of examining in greater depth the influence of physiology on articulation. Physiological parameters are assumed to be very similar in MZ twin pairs in contrast to DZ twin pairs or unrelated speakers, and it is hypothesized that the speaker specific shape of articulatory looping trajectories of the tongue is at least partly dependent on biomechanical properties and the speaker's individual physiology. By means of electromagnetic articulography (EMA), inter-speaker variability in the looping trajectories of the tongue back during /VCV/ sequences is analyzed. Results reveal similar looping patterns within MZ twin pairs but in DZ pairs differences in the shape of the loop, the direction of the upward and downward movement, and the amount of horizontal sliding movement at the palate are found.

Acoustic Change Over Time in Spastic and/or Flaccid Dysarthria in Motor Neuron Diseases.

PURPOSE: This study aims to investigate acoustic change over time as biomarkers to differentiate among spastic-flaccid dysarthria associated with amyotrophic lateral sclerosis (ALS), spastic dysarthria associated with primary lateral sclerosis (PLS), flaccid dysarthria associated with spinal and bulbar muscular atrophy (SBMA), and to explore how these acoustic parameters are affected by dysarthria severity. METHOD: Thirty-three ALS patients with mixed flaccid-spastic dysarthria, 17 PLS patients with pure spastic dysarthria, 18 SBMA patients with pure flaccid dysarthria, and 70 controls, all French speakers, were included in the study. Speakers produced vowel-glide sequences targeting different vocal tract shape changes. The mean and coefficient of variation of the total squared change of mel frequency cepstral coefficients were used to capture the degree and variability of acoustic changes linked to vocal tract modifications over time. Differences in duration of acoustic events were also measured. RESULTS: All pathological groups showed significantly less acoustic change compared to controls, reflecting less acoustic contrast in sequences. Spastic and mixed spastic-flaccid dysarthric speakers showed smaller acoustic changes and slower sequence production compared to flaccid dysarthria. For dysarthria subtypes associated with a spastic component, reduced degree of acoustic change was also associated with dysarthria severity. CONCLUSIONS: The acoustic parameters partially differentiated among the dysarthria subtypes in relation to motor neuron diseases. While similar acoustic patterns were found in spastic-flaccid and spastic dysarthria, crucial differences were found between these two subtypes relating to variability. The acoustic patterns were much more variable in ALS. This method forms a promising clinical tool as a diagnostic marker of articulatory impairment, even at mild stage of dysarthria progression in all subtypes.

Seeing Speech Production Through the Window of Complex Interactions: Introduction to the Supplement of Select Papers From the 10th International Seminar on Speech Production (ISSP) in Cologne.

Purpose: As the famous linguist and anthropologist C. Hockett noted about 30 years ago, "What one sees of language, as of anything, depends on the angle of view, and different explorers approach from different directions. Unfortunately, sometimes they become so enamored of their particular approach that they incline to scoff at any other, so that instead of everybody being the richer for the variety, everybody loses. … It is obviously impossible to see all of anything from a single vantage point. So it is never inappropriate to seek new perspectives" (Hockett, 1987, p. 1). This supplement takes such a broad perspective and contains a selection of peer-reviewed papers seeing speech production through the window of complex interactions between physical, linguistic, social, and communicative factors. Papers were presented at the 10th International Seminar on Speech Production in Cologne. We hope to encourage the reader to continue working in this exciting direction.

Voice Quality and Gender Stereotypes: A Study of Lebanese Women With Reinke's Edema.

Purpose: Women with Reinke's edema (RW) report being mistaken for men during telephone conversations. For this reason, their masculine-sounding voices are interesting for the study of gender stereotypes. The study's objective is to verify their complaint and to understand the cues used in gender identification. Method: Using a self-evaluation study, we verified RW's perception of their own voices. We compared the acoustic parameters of vowels produced by 10 RW to those produced by 10 men and 10 women with healthy voices (hereafter referred to as NW) in Lebanese Arabic. We conducted a perception study for the evaluation of RW, healthy men's, and NW voices by naïve listeners. Results: RW self-evaluated their voices as masculine and their gender identities as feminine. The acoustic parameters that distinguish RW from NW voices concern fundamental frequency, spectral slope, harmonicity of the voicing signal, and complexity of the spectral envelope. Naïve listeners very often rate RW as surely masculine. Conclusions: Listeners may rate RW's gender incorrectly. These incorrect gender ratings are correlated with acoustic measures of fundamental frequency and voice quality. Further investigations will reveal the contribution of each of these parameters to gender perception and guide the treatment plan of patients complaining of a gender ambiguous voice.

Application of concepts from cross-recurrence analysis in speech production: an overview and comparison with other nonlinear methods.

PURPOSE: The aim of this article was to introduce an important tool, cross-recurrence analysis, to speech production applications by showing how it can be adapted to evaluate the similarity of multivariate patterns of articulatory motion. The method differs from classical applications of cross-recurrence analysis because no phase space reconstruction is conducted, and a cleaning algorithm removes the artifacts from the recurrence plot. The main features of the proposed approach are robustness to nonstationarity and efficient separation of amplitude variability from temporal variability. METHOD: The authors tested these claims by applying their method to synthetic stimuli whose variability had been carefully controlled. The proposed method was also demonstrated in a practical application: It was used to investigate the role of biomechanical constraints in articulatory reorganization as a consequence of speeded repetition of CVCV utterances containing a labial and a coronal consonant. RESULTS: Overall, the proposed approach provided more reliable results than other methods, particularly in the presence of high variability. CONCLUSION: The proposed method is a useful and appropriate tool for quantifying similarity and dissimilarity in patterns of speech articulator movement, especially in such research areas as speech errors and pathologies, where unpredictable divergent behavior is expected.