Voix humaine | EPFL Graph Search

La voix humaine est l'ensemble des sons produits par le frottement de l'air des poumons sur les replis du larynx de l'être humain. La voix inclut la parole et le chuchotement, le cri, le rire et le chant. L'étude des sons produits par la voix humaine s'appelle la phonétique. C'est une des branches de la linguistique. Dans le domaine de la médecine, l'étude de la physiologie et de la pathologie de la voix et les soins de santé qui lui sont apportés sont du ressort de la phoniatrie. L'orthophonie s'occupe de la rééducation fonctionnelle de la voix. La voix est un instrument à la fois dans sa fonction physico-acoustique de communication avec l'autre, et dans sa fonction psychologique ou de lien à l'autre et à soi-même, donc dans sa fonction pragmatique et identitaire. Appareil phonatoire Les organes qui assurent la production vocale constituent lappareil phonatoire ou appareil de la phonation. Cet ensemble convertit le souffle en sons en plusieurs étapes : la soufflerie alimentée par l'appareil respiratoire (contrôlé et régulé par les appuis et le système musculaire abdomino-diaphragmatique) ; l'émission par l'appareil de production sonore constitué par le larynx, cavité mobile à l’extrémité de la trachée où se trouvent les cordes vocales dont la vibration module très rapidement le débit (et la pression) d'air, tandis que les muscles laryngés permettent d'ajuster la hauteur du son et dans une certaine mesure le timbre (contenu harmonique) ; l'amplification assurée par des résonateurs (pharynx, cavité buccale, les cavités crâniennes, la masse osseuse) ; l'articulation grâce au bout de la langue, du voile du palais, des gencives supérieures, des incisives supérieures et des deux lèvres. Les cavités buccales et nasales altèrent le timbre de la voix et un peu la hauteur : elles favorisent certaines fréquences au détriment d'autres en fonction de leur forme et de leurs dimensions, et réagissent avec la cavité laryngée. Les hommes et les femmes ont des cordes vocales de tailles différentes ; les hommes adultes ont généralement une voix plus grave et des cordes vocales plus longues, entre .

Multi-parametric source-filter separation of speech and prosodic voice restoration

Olaf Schleusing

In this thesis, methods and models are developed and presented aiming at the estimation, restoration and transformation of the characteristics of human speech. During a first period of the thesis, a concept was developed that allows restoring prosodic voice features and reconstruct more natural sounding speech from pathological voices using a multi-resolution approach. Inspired from observations with respect to this approach, the necessity of a novel method for the separation of speech into voice source and articulation components emerged in order to improve the perceptive quality of the restored speech signal. This work subsequently represents the main part of this work and therefore is presented first in this thesis. The proposed method is evaluated on synthetic, physically modelled, healthy and pathological speech. A robust, separate representation of source and filter characteristics has applications in areas that go far beyond the reconstruction of alaryngeal speech. It is potentially useful for efficient speech coding, voice biometrics, emotional speech synthesis, remote and/or non-invasive voice disorder diagnosis, etc. A key aspect of the voice restoration method is the reliable separation of the speech signal into voice source and articulation for it is mostly the voice source that requires replacement or enhancement in alaryngeal speech. Observations during the evaluation of above method highlighted that this separation is insufficient with currently known methods. Therefore, the main part of this thesis is concerned with the modelling of voice and vocal tract and the estimation of the respective model parameters. Most methods for joint source filter estimation known today represent a compromise between model complexity, estimation feasibility and estimation efficiency. Typically, single-parametric models are used to represent the source for the sake of tractable optimization or multi-parametric models are estimated using inefficient grid searches over the entire parameter space. The novel method presented in this work proposes advances in the direction of efficiently estimating and fitting multi-parametric source and filter models to healthy and pathological speech signals, resulting in a more reliable estimation of voice source and especially vocal tract coefficients. In particular, the proposed method is exhibits a largely reduced bias in the estimated formant frequencies and bandwidths over a large variety of experimental conditions such as environmental noise, glottal jitter, fundamental frequency, voice types and glottal noise. The methods appears to be especially robust to environmental noise and improves the separation of deterministic voice source components from the articulation. Alaryngeal speakers often have great difficulty at producing intelligible, not to mention prosodic, speech. Despite great efforts and advances in surgical and rehabilitative techniques, currently known methods, devices and modes of speech rehabilitation leave pathological speakers with a lack in the ability to control key aspects of their voice. The proposed multiresolution approach presented at the end of this thesis provides alaryngeal speakers an intuitive manner to increase prosodic features in their speech by reconstructing a more intelligible, more natural and more prosodic voice. The proposed method is entirely non-invasive. Key prosodic cues are reconstructed and enhanced at different temporal scales by inducing additional volatility estimated from other, still intact, speech features. The restored voice source is thus controllable in an intuitive way by the alaryngeal speaker. Despite the above mentioned advantages there is also a weak point of the proposed joint source-filter estimation method to be mentioned. The proposed method exhibits a susceptibility to modelling errors of the glottal source. On the other hand, the proposed estimation framework appears to be well suited for future research on exactly this topic. A logical continuation of this work is the leverage the efficiency and reliability of the proposed method for the development of new, more accurate glottal source models.

EPFL2012

Multi-parametric source-filter separation of speech and prosodic voice restoration

Olaf Schleusing

EPFL2012