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Introduction Les excursions du Centre de Pression (CdeP) chez le sujet normal en station naturelle consistent en deplacements stochastiques, limites en amplitude et lies dans leur succession. En application de la theorie fractale des mouvements browniens (Mandelbrot et van Ness) Collins et de Luca ont montre que la moyenne des carres du deplacement sagittal observe pendant un intervalle dt etait liee a dt par une constante de Diffusion D, et plus generalement par un exposant fractionnaire H, facteur « d’echelle ». Leurs diagrammes de diffusion f(dt) distinguent une zone de diffusion D1 rapide et « persistante » (H > 0.5, dt Materiels et methodes Nos logiciels domestiques ont traite des stabilogrammes sagittaux issus de jeunes adultes normaux, etablis sur plateforme de force. Durees d’analyse 51,2 s. Les diagrammes de Diffusion et AC ont ete mis en inter-correlation. Resultats Le profil de Diffusion est identique au profil AC, au signe et a une constante d’ordonnee pres (deux fois la variance du stabilogramme). Le coefficient d’inter-correlation est de 0,98. Pour un sujet donne le traitement des deux profils produit les memes valeurs D1, D2, et les memes coordonnees de point critique. Discussion S’il est possible d’exhiber sur le profil de l’AC les memes parametres que ceux mesures par Collins et De le Luca, leur lecture renvoie plus a des notions de dependances internes du signal, de memoire du systeme, de regularites, etc. Cette caracterisation ne prejuge en rien de l’existence de deux processus, « open and closed loop » en deca et en dela d’un point critique qui nous parait par ailleurs mal fonde. S’agissant de l’AC est de sa caracterisation, nous proposons un marqueur de « la memoire du systeme », qui est aussi un delai critique pour lequel l’autocorrelation est nulle (zero-crossing). Une regression exponentielle de l’AC, telle la courbe de decharge d’un condensateur, permet d’exhiber la constante de temps du systeme (AC = 0,37) et la pente a l’origine qui determine la vitesse de decroissance de l’AC.

Background Many authors have studied adult’s larynx modelization, but the mechanisms of newborn’s voice production have very rarely been investigated. After validating a numerical model with acoustic data, studies were performed on larynges of human fetuses in order to validate this model with aerodynamical experiments. Material and methods Anatomical measurements were performed and a simplified numerical model was built using Fluent ® with the vocal folds in phonatory position. The results obtained are in good agreement with those obtained by laser Doppler velocimetry (LDV) and high-frame rate particle image velocimetry (HFR-PIV), on an experimental bench with excised human fetus larynges. Results It appears that computing with first cry physiological parameters leads to a model which is close to those obtained in experiments with real organs.

This study was carried out using a transversal design. It aimed to investigate possible changes of the normal voice in children before mutation, to create a database for the parameters used in the study, and to examine the use of fractal dimension and the largest Lyapunov exponent (LLE) in the assessment of nonpathological phenomena. Two hundred twelve children were enrolled: 111 females and 101 males; and 9 six-year-olds, 24 seven-year-olds, 18 eight-year-olds, 25 nine-year-olds, 27 ten-year-olds, 55 eleven-year-olds, and 54 twelve-year-olds. Fundamental frequency (Fo) decreased with age and was lower in boys than in girls. Jitter and shimmer did not significantly differ with age or gender. Fractal dimension and LLE were significantly lower in boys; LLE decreased with age. The present series confirmed the established findings that Fo is lower in boys than in girls, even before mutation, and decreases with age; two other classical voice analysis parameters, jitter and shimmer, also showed the same behavior as described in the literature. The study of nonlinear parameters (fractal dimension and LLE) showed that laryngeal dynamics is more stable in boys than in girls, and that stability is correlated with age.

Summary A new method of measuring the resonance properties of a vocal fold using electromagnetic excitation and laser optoreflectometry for response monitoring is described. Two resonance peaks were experimentally identified with one magnet stuck on the vocal fold at frequencies F0 1m =54.7Hz and F0′ 1m =35.8Hz. The addition of a second magnet allowed calculation of the actual viscoelastic properties of the vocal fold: F0=71.8Hz; quality factor Q =8.03; mass m =0.057g; stiffness k =11.6Nm; and damping ζ =0.0032Nm −1 . A numerical simulation of a two-layered model verified the experimental data.

Voice of patient with unilateral laryngeal paralysis (ULP) shows a nonlinear behaviour with sudden octave jumps, bifurcations and chaos. Such a behaviour may be due to an increased number of freedom degrees in the glottal system. We hypothesized that voice intensity (with increasing sub glottal pressure) could improve vocal signal stability with less freedom degrees in vibrating system, and then a decrease of nonlinearities. A prospective study of 32 consecutive voices of patients with ULP and severe dysphonia was conducted. Jitter and Lyapunov exponent from vocal signals were compared at comfortable and loud voicing with Wilcoxon’s test. In 23 out of 32 patients, jitter significantly decreased from 5 (median) in normal voice to 1.2 in loud voice (P < 10−3), Lyapunov exponent decreased from 1,495 bit/s (median) to 708 bit/s (P < 10−4). Two patients had paradoxical results regarding jitter (higher in loud voice) and 2 regarding Lyapunov exponent. From the 23 cases of voice improvement, 15 cases showing a marked improvement of the acoustic analysis supported our hypothesis (65%). Nonlinear phenomena detected in vocal signals of ULP with severe dysphonia may be reduced in loud voice.

This study describes a novel system allowing the noncontact measurement of vibration of each vocal fold. The system is based on reflectometry, i.e. measurement of light bouncing off a vibrating object. The system works in natural light and is sensitive, compact, and inexpensive. We have used this system for separate and simultaneous detection of the vibration of each vocal fold in excised porcine larynges. Normal conditions of vibration and asymmetry of tension leading to biphonations were studied. Analysis of each vibrating cycle reveals interaction between the vocal folds allowing synchronous vibration despite their physical asymmetry or episodes of period doubling.

The purpose was to determine the clinical value of a multiparametric objective voice evaluation protocol including acoustic and aerodynamic parameters measured mainly on a sustained /a/. This was done by comparison with perceptual analysis of continuous speech by a jury composed of 6 experienced listeners. Voice samples (continuous speech) from 63 male patients with dysphonia and 21 control subjects with normal voices were recorded and assesed by a jury of listeners. The jury was instructed to classify voice samples according to the G (overall dysphonia) component of the GRBAS score on a 4-point scale ranging from 0 for normal to 3 for severe dysphonia. Objective parameters were recorded on an EVA workstation. As usual with this type of system, parameters were measured mainly on a sustained /a/. Measured parameters included fundamental frequency (F0), intensity, jitter, shimmer, signal-to-noise ratio, Lyapunov coefficient (LC), oral airflow (OAF), maximum phonatory time (MPT), and vocal range (range). Estimated subglottic pressure (ESGP) was determined on a series of /pa/. Discriminant analysis was performed to detect correlation between jury classification and combinations of parameters. Results showed that a nonlinear combination of only six parameters (range, LC, ESGP, MPT, signal-to-noise ratio, and F0) allowed 86% concordance with jury classification. Discussion deals with the relative importance of the different objective parameters for discriminant analysis. Special emphasis is placed on two measurements rarely made in routine clinical workup, i.e., estimated subglottic pressure and Lyapunov coefficient.

The stabilometry signals involve irregular and unpredictable components. In order to identify the hidden dynamics that underlie the multi-link networks consisted of the multiple sensory systems, motor components and central integration, we applied a nonlinear analysis to these signals. We evaluated the postural control differences between eyes open and closed by means of the dynamical closeness between two states, known as similarity index, for the patients with vestibular disorders. We were able to demonstrate that some patients (eight of 21) showed a difference between the conventional and nonlinear measures. Especially, the similarity index tended to reflect the clinical course of the vestibular compensation and the findings in the patients with benign paroxysmal positional vertigo (BPPV) demonstrated that its vestibular function may include various pathologies besides canalithiasis. These results suggest that nonlinear analysis can elucidate the complex postural control networks and this procedure may also be able to provide the new findings of the stabilometry examinations.

We proposed to study and quantify the anteroposterior component, on top of the lateral one, of the body sway induced by different configurations of galvanic vestibular stimulation (GVS) in order to advance the understanding of the orientation of the response. Four stimulation configurations were used in two separate experiments: monaural, binaural, and opposite double monaural in the first experiment (11 subjects); monaural and double monaural in the second (13 subjects). The postural response of the subjects, standing with their eyes closed, to the stimulus (0.6 mA, 4 s) was assessed by measuring the displacement of the center of pressure (CoP) using a force platform. As usual, binaural GVS induced a strictly lateral deviation of the center of pressure. The opposite double monaural condition induced a similar lateral sway to that obtained in the binaural mode, although with a very different stimulation configuration. Monaural GVS induced an oblique, stereotyped deviation in each subject. The anteroposterior component comprised a forward deviation when the anode was on the forehead and a backward deviation when the anode was on the mastoid. The lateral component, directed towards the anode as in the binaural design, was twice as large in the binaural than in the monaural mode. The second experiment showed that double monaural stimulation elicited an anteroposterior deviation (backwards when the anode was on the mastoids and forwards when it was on the forehead) that was equivalent to the addition of two complementary monaural configurations. The present results show that monaural stimulation activates one side of the vestibular apparatus and induces reproducible, stereotyped deviations of the CoP in both the anteroposterior and lateral plane. Secondly, binaural GVS appears to result from the addition of two complementary monaural stimulations. Lateral components of the response to each stimulation, being in the same direction, are summed, whilst anteroposterior components, being in opposite directions, cancel each other out. The opposite happens when both labyrinths are polarized in the same way, as in the double monaural configuration. We suggest that the orientation of the response to GVS is a function of the imbalance between right and left vestibular polarization, rather than a function of the actual position of the electrodes.

Summary Coupling between the vocal folds is one of the nonlinear mechanisms allowing regulation and synchronization of mucosal vibration. The purpose of this study was to establish that modulations such as diplophonia and abnormalities observed in vocal signals that may be observed in some cases of laryngeal pathology can be considered as nonlinear behavior due to the persistence of some physical interaction (coupling). An experimental model using excised porcine larynx was designed to create tension asymmetry between the vocal folds and to obtain vocal signals with modulations. Signals were analyzed by spectral analysis and the phase portrait method. Results were compared with computer-generated synthetic signals corresponding to nonlinear combinations of sinusoid signals. Under these conditions, evidence of nonlinear behavior was detected in 85% of experimental signals. These findings were interpreted as a demonstration of vocal fold interaction. Based on these findings, the authors conclude that (1) coupling must be taken into account in physical models of laryngeal physiology, and that (2) methods of nonlinear dynamics may be used for objective voice analysis.

Introduction Des excursions posturales sagittales se manifestent en permanence chez l’homme debout immobile. Elles se developpent en mode pseudo-aleatoire spontanement de part et d’autre de la posture habituelle du sujet. L’implementation anthropometrique plausible d’un pendule inverse theorique mecaniquement equivalent d’un homme reel permet de definir la neuro-biomecanique de ses excursions. Dans le cas usuel ou la raideur intrinseque tricipitale (KAG) est inferieure a la raideur de charge gravitationnelle (KG), le modele impose une activation repetitive tricipitale qui encadre de facon statistique le tonus antigravitaire moyen. L’analyse des excursions concretes de sujets reels confirme cette inference. Nous montrons par implementation plausible des equations d’equilibre dynamique du pendule inverse qu’un « controle de position realise par des relaxations repetees d’energie » simule des excursions fictives du CdeP et du CdeM qui ne sont pas statistiquement differentes des excursions naturelles. Materiel et methodes L’implementation des parametres de notre modele numerique a ete renseignee par l’observation et l’analyse posturale chez 5 jeunes adultes etudiants. L’usage d’une plateforme de force, d’une sonde electromagnetique et d’electrodes de surface, nous ont permis de recueillir respectivement : les excursions du CdeP, le CdeM, les EMGs soleaire. Notre simulation numerique du controle postural se fonde sur le processus de relaxation des oscillateurs non lineaires regis par l’equation de Van der Pol… L’integration numerique des equations differentielles s’effectue par la methode de Runge Kutta. Resultats Les simulations observees produisent des profils CdP et CdM spontanement aleatoires, a l’interieur de limites statistiques sans qu’il soit necessaire d’introduire du bruit. Les caracteristiques, spatiales, temporelles, frequentielles, etc. des signaux obtenus sont par ailleurs comparables a celles de l’experimentation. Conclusions Le modele est simple et robuste. Il est en adequation avec l’observation experimentale. Des correlats neurophysiologiques sont envisages sur la base d’une analyse critique de l’actualite en la matiere.

Introduction Les descripteurs de l’instabilite posturale constituent une masse d’informations qui va croissant, et dans laquelle le clinicien risque de se perdre. Le profil postural que nous proposons ici est un schema synthetique facilitant l’interpretation du posturogramme. Ce mode de representation permet d’un seul coup d’œil d’entrer dans la logique du controle postural en decrivant sa precision, sa depense d’energie, sa symetrie, ses tensions musculaires, ses degres de liberte, ses rapports aux differents capteurs, etc. Contrairement au systeme expert, ce mode de representation du bilan posturometrique ne s’appuie que sur les donnees objectives du sujet rapportees aux statistiques d’une base normative. Quinze descripteurs representatifs du profil postural ont ete regroupes selon des « traits » identifies du caractere du controle postural que sont : vision, asymetrie, instabilite, neurologie, coordination, rigidite (VAINCR). Materiel et methodes La base normative inclut les donnees posturometriques de 500 sujets examines yeux ouverts et yeux fermes, soit 1000 enregistrements effectues sur plateformes jumelles compatibles avec les normes AFP 40/16 et selon un protocole standardise. Pour ne conserver que les parametres discriminants et operer leur regroupement, une analyse en composantes principales a ete appliquee. Pour donner un caractere universel aux mesures du profil postural, tous les descripteurs ont ete standardises en utilisant les ecarts-types (σ) de la base. Pour chaque descripteur discriminant, 4 grades de performances posturales (de l’excellence a la « pathologie ») sont representes sur un graphique par 4 cercles concentriques, de rayons : 0,1σ, σ, 2σ, et 4σ. Conclusions Ce mode de representation met a la disposition du clinicien un moyen puissant d’appreciation des performances posturales sans qu’il soit necessaire d’entrer dans le detail de ses constituants.

International audience; For fifteen years, we have developed and studied different techniques and methodologies to assess voice quality in a clinical context. This paper exposes recent results obtained by complementary approaches. 449 speakers (including 391 dysphonic patients) participated in the experiment where voice quality was evaluated by (1) perceptual voice assessment performed by a jury and (2) instrumental voice assessment using acoustic and aerodynamic data. Results showed that a combination of 7 instrumental measures allowed the classification of 82% voice samples in the same grade as the jury. We evaluate the methodological situation and we also discuss some theoretical aspects which are often forgotten in the performance race.; Dans le domaine de la phonétique, l'analyse de la qualité de la voix est généralement intégrée dans l'étude des phénomènes paralinguistiques de la communication parlée (Laver, 1981). Actuellement, la majorité des études dans le domaine portent sur les relations entre l'état émotionnel du locuteur et les indices acoustiques portés par le signal vocal, ou encore sur la variabilité de la qualité de la voix en fonction de facteurs dialectaux et socioculturels (Gobl et al., 2003). Dans notre cas, depuis une quinzaine d'années (Giovanni et al., 1991), nous nous sommes penchés plus particulièrement sur les relations entre état physiologique du locuteur et qualité vocale, notamment dans un cadre clinique de dysfonctionnement du système pneumo phonatoire. Dans ce cadre de la prise en charge des dysphonies, l'étape de l'évaluation vocale est apparue nécessaire pour permettre des comparaisons entre les différentes formes de pathologies, entre patients, pour contrôler l'évolution longitudinale de l'état vocal ou encore des différentes solutions thérapeutiques. Les deux principales méthodes retenues sont le jugement perceptif et les mesures instrumentales multiparamétriques. La première méthode consiste à faire juger la qualité vocale de patients par des experts (phoniatres, orthophonistes) dont le rôle est de fournir un grade de dysphonie sur une échelle GRBAS proposée par Hirano (1981). Le principe est de faire lire au patient un texte normalisé dont l'énoncé enregistré est ensuite soumis en aveugle à quatre juges expérimentés qui attribuent une note entre 0 (normal) et 3 (dysphonie sévère) par catégorisation directe ou à travers des échelles analogiques visuelles interprétées (Yu et al., 2002). Dans la plupart des cas, seul le grade G (global, général) de la dysphonie est exploité. Du fait des limites rencontrées par cette approche (Bonastre et al., 2007), des mesures instrumentales sont effectuées parallèlement sur les patients à l'aide du dispositif EVA (Teston et al., 1995) qui permet d'obtenir des mesures acoustiques de stabilité laryngée (jitter, shimmer, coefficient de Lyapounov), des estimations de performance pneumo-phonatoire (étendue vocale, temps maximal de phonation) et des grandeurs aérodynamiques qui explorent de façon directe et sélective certains mécanismes comme la fuite glottique (par mesure de débit d'air oral) ou la tension de la source (par estimation de la pression sous-glottique). Dans une étude récente (Yu et al. , 2007), 449 locuteurs (incluant 391 patients dysphoniques) ont été soumis à cette double évaluation perceptive et instrumentale. Les résultats montrent qu'une combinaison de six paramètres physiques (Etendue vocale, Coefficient de Lyapounov, Pression Sous-glottique estimée, Temps maximal de phonation, débit d'air oral et rapport signal/bruit) autorisent une classification identique à l'évaluation perceptive dans 82% des cas. Ce résultat est encourageant par rapport à d'autres études comme celle de Wuyts et al. (2000) mais l'adéquation reste insuffisante pour une utilisation clinique de routine. Nous pensons qu'il s'agit essentiellement d'une limite méthodologique liée à la relation non bijective entre espace perceptif et mesures physiques. De plus, les techniques instrumentales utilisées ont été conçues pour une approche analytique descendante fondée sur la mesure objective (ex : soupçon de fuite glottique => mesure de débit d'air) alors qu'elles sont utilisées comme des "machines à écouter" avec une approche montante, globale et "aveugle". Nos perspectives sont diverses. Tout d'abord, l'utilisation de techniques issues de la reconnaissance automatique du locuteur adaptées à la classification du grade de dysphonie semble prometteuse (Pouchoulin et al., 2007) car ces méthodes sont aptes, du fait de la phase d'apprentissage, à "imiter" le jugement perceptif. D'autre part, les techniques instrumentales "classiques" devraient s'utiliser pour la mesure objective à des fins de suivi longitudinal ou d'évaluation ciblée sur une ou quelques dimensions du dysfonctionnement vocal. Enfin, l'étude des relations entre perception et signal vocal devrait être appréhendée pour se rapprocher d'une évaluation auditive plus précise, comme celle de l'intelligibilité, et moins globale comme proposé par Hammarberg et al. (1980), avec notamment des liens avec la physiopathologie. Le recours à de la synthèse de voix pathologiques serait d'un grand intérêt pour explorer les relations perception/acoustique et pour avoir des matériaux calibrés pour tester les techniques de mesures objectives.

Objectives: One postural characteristic of increased vocal effort is stiffening of the whole body, which in turn induces some postural instability. The study of postural instability can shed some insight into behavior or causes associated with vocal hyperfunction. Patients and Methods: A posturography platform was used to measure the root mean square of the velocity of variation of the center of pressure (VCOP rms) of control subjects standing upright on the platform. Four conditions were analyzed: (1) standing with eyes open versus eyes closed (n: 9); (2) standing at rest versus holding a 3-kg weight (n: 15); (3) standing while reading a dialogue at normal voice level versus loud voice (n: 17), and (4) standing while reading a dialogue in a calm versus noisy (Lombard effect) ambiance (n: 19). Results: Conditions leading to a stiffening of the body (eyes closed and weight holding) were associated with an increased instability assessed by the VCOP rms. In phonatory conditions leading to vocal effort, the mean VCOP rms was significantly increased: in 19 subjects reading a dialogue in a calm ambiance the mean VCOP rms was at 11.19 mm/s, and the VCOP rms raised 16.69 mm/s with surrounding noise at 82 db (Lombard effect). Conclusion: Increased vocal effort is associated with increased VCOP rms in most subjects studied. The effects of VCOP rms as a postural index allowing noninvasive assessment of the voice in pathology warrants further study.

Within the last 3 decades, microsurgery and stereotactic radiosurgery (SRS) have become well-established management options for vestibular schwannomas (VSs). Advancement in the management of VSs can be separated into three periods: the microsurgical pioneer period, the demonstration of SRS as a first-line therapy for small and medium-sized VSs, and currently, a period of SRS maturity based on a large worldwide patient accrual. The Marseille SRS experience includes 1,500 patients, with 1,000 patients having follow-up longer than 3 years. A long-term tumor control rate of 97%, transient facial palsy lower than 1%, and a probability of functional hearing preservation between 50 and 95% was achieved in this large series of patients treated with state-of-the-art SRS.

Within the last 3 decades, microsurgery and stereotactic radiosurgery (SRS) have become well-established management options for vestibular schwannomas (VSs). Advancement in the management of VSs can be separated into three periods: the microsurgical pioneer period, the demonstration of SRS as a first-line therapy for small and medium-sized VSs, and currently, a period of SRS maturity based on a large worldwide patient accrual. The Marseille SRS experience includes 1,500 patients, with 1,000 patients having follow-up longer than 3 years. A long-term tumor control rate of 97%, transient facial palsy lower than 1%, and a probability of functional hearing preservation between 50 and 95% was achieved in this large series of patients treated with state-of-the-art SRS.

International audience; OBJECTIVES:Pitch change during voice production is under the control of auditive and kinesthetic feedback phenomenona. The aim of the study was to determine the role of larynx kinesthetic feedback in speech production control.MATERIALS AND METHODS:To validate our laryngeal model, five porcine larynges were excised and placed on a test bench consisting of a blower and a laser photoglottometer for measurement of vocal cord vibration. We applied vibratory stimuli to the cricothyroid muscles to determine whether vibrators supplied by a generator alter the biomechanics of the larynx. Fundamental frequency (F0) was recorded under three conditions--larynx on vibration--larynx on vibration with vibrators activation--larynx on rest and vibrators activation. Once validated, 7 male and 7 female, mean age 29 years, were enrolled. Vibrators were positioned on cricothyroid muscles, cricoid and thyroid cartilages. Masking noise was used. Fundamental frequency, intensity and speech time production was measured during speech production under three conditions--normal speech, vibrators activation, and masking activation.RESULTS:The preliminary study demonstrated that larynx on vibration with vibrators activation doesn't alter the vocal fold F0. For the human trial, between normal speech and vibrators activation conditions, we found a significant difference (p= 0.045 for male, p= 0.010 for female) in intonation, and no significant difference for intensity and speech time. Between normal speech and masking activation conditions, no significant differences were measured for any condition.CONCLUSION:Use of the vibrators is a reliable method to allow the evaluation of larynx kinesthetic feedback in speech production control.; Objectif: le contrôle de la hauteur de la voix au cours de la production de la parole obéit à un schéma intonatif mélodique qui dépend aussi bien de phénomènes auditifs que proprioceptifs. Le but de cette étude fut d'évaluer le rôle de la proprioception laryngée dans le contrôle de la production de la parole. Matériels et méthodes : pour valider notre modèle laryngé, cinq larynx de porc excisés, furent placés sur un banc expérimental doté d'une soufflerie avec un laser photoglottomètre permettant la mesure de la vibration vocale. Les muscles cricothyroidiens furent soumis à une vibration alimentée par un générateur, pour déterminer si la présence de vibreurs altère la biomécanique du larynx. La fréquence fondamentale (F0) fut enregistrée sous trois conditions- larynx en vibration - larynx en vibration et activation des vibreurs - larynx au repos et activation des vibreurs. Après validation, 7 hommes et 7 femmes, âge moyen 29 ans, participèrent à cette étude. Les vibreurs furent positionnés en regard des muscles laryngés, des cartilages thyroïdes et cricoïdes; un masking auditif fut utilisé. La fréquence fondamentale, l'intensité et la durée d'émission furent analysés sous trois conditions -production normale de la parole - activation des vibreurs -activation du masking. Résultats : l'étude préliminaire démontra que l'utilisation des vibreurs n'altérait pas la F0 des cordes vocales. L'essai chez l'homme, mit en évidence une différence significative entre la production de la parole et l'activation des vibreurs pour l'intonation (homme p= 0,045, femme p= 0,010), et aucune différence significative pour l'intensité et la durée d'émission. Aucune différence significative entre la production de la parole et l'utilisation du masking ne fut retrouvée, sous aucune des conditions. Conclusion : l'utilisation des vibreurs apparut comme une méthode fiable pour permettre l'étude de la proprioception laryngée dans le contrôle de la production de parole.

Objectives/Hypothesis: This report describes a comparative study of objective voice evaluation using a multiparametric protocol including aerodynamic parameters and linear and nonlinear acoustic parameters recorded on an EVA® workstation and perceptual voice analysis by a jury. Study Design: A total of 449 samples were retrospectively selected including 391 patients with pathological voices (308 women and 141 men) and 58 controls with normal voices (38 women and 20 men). A prospective complementary study concerning 43 female patients and 3 controls is presented. Methods: Objective measures included fundamental frequency (Fo), intensity, jitter, signal-to-noise ratio (SNR), Lyapunov coefficient (Lya), oral airflow (OAF), estimated subglottic pressure (ESGP), maximum phonatory time (MPT) and vocal range. A jury of 4 experienced listeners was instructed to classify voice samples (continuous speech) according to the G (overall dysphonia) component of the GRBAS score on a Visual Analogue Scale (VAS) secondarily transformed in a scale ranging from 0 for normal to 3 for severe dysphonia. Results: It was shown that a nonlinear combination of only 7 parameters in women (vocal range, Lya, ESGP, MPT, OAF, SNR, and Fo) and 6 parameters in men (vocal range, Lya, OAF, ESGP, Fo, SNR) allowed classification of 81% voice samples in the same grade as the jury in women and 84% in men. In the prospective study, 80.5% were correctly classified with the same set of objective measurements. Discussion: The relative importance of the different objective parameters in this type of discriminant analysis is dealt with. Special emphasis is placed on Lya.

Summary Well-known multimass models of vocal folds are useful to describe main behavior observed in human voicing but their principle of functioning, based on harmonic oscillation, may appear complex. This work is designed to show that a simple one-mass model ruled by laws of relaxation oscillation can also depict main behavior of glottis dynamic. Theory of relaxation oscillation is detailed. A relaxation oscillation model is assessed through a numerical simulation using conventional values for tissue characteristics and subglottal pressure. As expected, raising the mass decreases the fundamental frequency and increases the amplitude of vocal fold vibration: for a mass ranging from 0.01 to 0.4 g, F 0 decreased from 297.5 to 42.5 Hz and vibrational amplitude increased from 1.26 to 3.25 mm (for stiffness k = 10 N m −1 , damping r = 0.015 N s m −1 , and subglottal pressure = 1 kPa). Stiffness value has the opposite effect. The subglottal pressure controls the fundamental frequency with a rate ranging from 20 to 50 Hz/kPa. The vibrational amplitude is also controlled linearly by subglottal pressure from 0.22 to 0.26 mm/kPa. The range of phonation threshold pressure (PTP) is close to the values currently proposed, that is, 0.1 to 1 kPa and varies with the fundamental frequency. The relaxation oscillator is a simple and useful tool for modeling vocal fold vibration.

International audience; Considering on the one hand the important histological differences that exist between newborn and adult vocal folds and on the other hand the specifical subglottal pressure at birth, the sound production in a newborn larynx is studied. The laryngotracheal airflow has been numerically modelled in order to evaluate its role in voice production by the larynx in newborn. The FFT spectrum of the pressure signal acquired just above the vocal folds was calculated and compared to the spectrum of a sound generated by an excised larynx. It can be determined that first, the computed pressure signal has a fundamental frequency close to that obtained experimentally with an excised larynx, and second the FFT spectra are qualitatively similar to one another. Third, the computed pressure fluctuation is strong enough to be detected by the human ear. The conclusion is that the airflow and the aerodynamical phenomena observed in a rigid geometry are, by themselves, able to produce a sound and consequently, are one of the several elements leading to sound production in the newborn larynx. #

Objective The aim of this study was to describe and analyze the vibratory pattern of vocal folds in an asymmetric situation. Study design and setting Cricothyroid muscle unilateral action was simulated on excised larynges on an experimental bench. Increasing airflow rates were applied to achieve vocal fold vibration. Electroglottography and an optoreflectometer device allowed analysis of separate and simultaneous vocal fold vibration. Spectra of the signals were obtained for each level of airflow variation. Results All experiments showed periodic vibration. A phase shift was noted between the two vocal folds. Subharmonics and biphonation were identified in all the experiments. Conclusion Lax vocal folds were more susceptible to spectral changes with increasing airflow. Significance Knowledge of the consequences of mass, tension, and position asymmetries of the vocal folds is crucial for diagnosis making and defining therapeutic strategies in dysphonic patients. This study may contribute to the understanding of physiology of vocal fold interaction and its compensatory mechanisms.

Summary Numerous clinical findings indicate that viscosity of laryngeal mucosa is a crucial factor in glottal perfomance. Experience using experimental test benches has shown the importance of humidifying air stream used to induce vibration in excised larynges. Nevertheless, there is a lack of knowledge particularly regarding the physicochemical properties of laryngeal mucus. The purpose of this study was to research vocal fold vibration in excised larynges using artificial mucus of precisely known viscosity. Eight freshly harvested porcine larynges were examined. Parameters measured were Fo and vocal fold contact time. Measurements were performed under three conditions: basal (no fluid application on vocal cord surface), after application of a fluid of 60cP viscosity (Visc60), and after application of a fluid of 100cP viscosity (Visc 100). Electroglottographic measurements were performed at two different times for each condition: 1 s after airflow onset (T1) and 6 seconds after airflow onset (T2). Statistical analysis consisted of comparing data obtained under each condition at T1 and T2. The results showed a significant decrease in Fo after application of Visc60 and Visc100 fluids and a decrease in Fo at T2. Closure time was significantly higher under Visc60 conditions and under Visc100 conditions than under basal conditions. Application of artificial mucus to the mucosa of the vocal folds lowered vibratory frequency and prolonged the contact phase. Our interpretation of this data is that the presence of mucus on the surface of the vocal folds generated superficial tension and caused adhesion, which is a source of nonlinearity in vocal vibration.

Summary It has been shown that voice signal abnormalities, particularly in unilateral laryngeal paralysis (ULP), are not always randomly distributed and that "statistical" indexes of regularity, such as jitter and shimmer, may be unreliable in these cases. The techniques of nonlinear dynamics, particularly phase portraits, have been used to demonstrate that some of the abnormalities observed were the consequence of nonlinearity of glottic function. From a theoretical point of view, determination of Lyapunov exponents allows quantification of the complexity of the phase portraits. The authors studied vocal signals recorded in 12 normal subjects and 26 patients with ULP and calculated the largest Lyapunov exponent (LLE). In normal subjects, LLE mean value was 0.380 (SD = 0.182). In patients with ULP, LLE mean value was 0.570 (SD = 0.337). The difference is significant at P = 0.031. Determination of LLE was compared to more "classical" indexes such as jitter and oral airflow during phonation. A principal component analysis showed that information contained in LLE was not redundant but complementary to the other parameters.

We investigated the possibility of obtaining an anteroposterior body response to galvanic vestibular stimulation (GVS) by applying an equivalent stimulus to both sides of the vestibular apparatus. An original ‘double fronto-mastoidal’ stimulation was used on eight subjects standing with their head facing forwards. Both the onset and the cut-off of the current did induce an anteroposterior body tilt, without any lateral component. The amplitude of the tilt increased as a function of stimulus intensity. GVS evokes anteroposterior or lateral sway of similar spatio-temporal features according to the stimulation configuration. We suggest that the central nervous system makes use of the discrepancy between the left and right vestibular activity to orientate the response: equivalent afferent flows would result in an anteroposterior body response whereas lateral sway is obtained with discrepant ones. © 1998 Elsevier Science Ireland Ltd.

Recovery of head postural control after unilateral vestibular neurectomy was investigated in the alert cat by chronically recording the spontaneous neck muscle EMG activity from splenius capitis on both sides and the vestibulocollic reflexes evoked during roll and pitch tilts. Neuronal correlates occurring within the lateral (Deiters) vestibular nuclei (LVN) were also recorded during the time-course of recovery. During the acute phase (1-2 weeks), the cats exhibited strong imbalance in spontaneous neck muscle activity, characterized by increased muscular tone in the ipsilateral splenius capitis muscle and hypoactivity in the contralateral one. At the same time, the mean resting activity of Deiters' neurons strongly decreased on the deafferented side, while a slight but significant decrease was observed on the intact side. Vestibulocollic reflexes were totally lacking during the acute phase, whatever the direction and the amplitude of tilt. Recovery developed in the following weeks, leading to complete rebalance of spontaneous EMG activity as well as near to normal static vestibulocollic reflexes 5 weeks after the lesion. However, compensation remained sub-normal during roll tilts while overcompensation was found during pitch tilts, suggesting that the intact labyrinth would play a leader role in the recovery process but that bilateral cooperation of the two labyrinths is required for proper head postural control. Five weeks are also needed for a partial rebalancing of resting activity between both LVN. These results indicate that changes in neck muscle activity observed in the acute cats and that recovery found in the compensated animals could result from modifications in neural networks controlling neck musculature, such as the LVN.

Objectives: In previous work, we showed that a rigid larynx-like geometry can generate a sound by itself. However, very little is known about the exact mechanisms and control of the larynx during the first cry of life. The goal of this work was to understand how the very first cry is generated. Methods: Simultaneous high-speed imaging and sound recording on 2 excised 38-week term human fetus larynges were performed. The behaviors of the vocal folds and the false vocal folds were studied separately. The behavior of the vocal folds after resection of the supraglottic structures was also analyzed. A comparative acoustic analysis of the first cry and of the sound generated by the excised organs was performed. Results: Our data showed that the vocal folds in a larynx with the pressure conditions of the first cry do not generate sound themselves, but induce aerodynamic conditions leading to vibrations of other parts of the larynx. Conclusions: The similarities between the sound generated by an excised larynx and the first cry suggest a lack of neurologic control of the larynx during production of the first cry. A model-algorithm is proposed.