Determination of articulatory parameters from speech waveforms

Imperial Users onl

Joint estimation of vocal tract and source parameters of a speech production model

This thesis describes algorithms developed to jointly estimate vocal tract shapes and source signals from real speech. The methodology was developed and evaluated using simple articulatory models of the vocal tract, coupled with lumped parametric models of the loss mechanisms in the tract. The vocal tract is modelled by a five parameter area function model [Lm, 1990] Energy losses due to wall vibration and glottal resistance are modelled as a pole- zero filter placed at the glottis. A model described in [Lame, 1982] is used to approximate the lip radiation characteristic. An articulatory-to-acoustic "linked codebook" of approximately 1600 shapes is generated and exhaustively searched to estimate the vocal tract parameters. Glottal waveforms (input signals) are obtained by inverse filtering real speech using the estimated vocal tract parameters. The inverse filter is constructed using the estimated area function. A new method is proposed to fit the Liljencrants - Fant glottal flow model [Fant, Liljencrants and Lm, 1985] to the inverse filtered signals Estimates of the parameters are found from both the inverse filtered signal and its derivative. The descnbed model successfully estimates articulatory parameters for artificial speech waveforms. Tests on recorded vowels suggest that the technique is applicable to real speech. The technique has applications in the development of natural sounding speech synthesis, the treatment of speech disorders and the reduction of data bit rates in speech codin

Spectral analysis of pathological acoustic speech waveforms

Biomedical engineering is the application of engineering principles and techniques to the medical field. The design and problem solving skills of engineering are combined with medical and biological science, which improves medical disorder diagnosis and treatment. The purpose of this study is to develop an automated procedure for detecting excessive jitter in speech signals, which is useful for differentiating normal from pathologic speech. The fundamental motivation for this research is that tools are needed by speech pathologists and laryngologists for use in the early detection and treatment of laryngeal disorders. Acoustical analysis of speech was performed to analyze various features of a speech signal. Earlier research established a relation between pitch period jitter and harmonic bandwidth. This concept was used for detecting laryngeal disorders in speech since pathologic speech has been found to have larger amounts of jitter than normal speech. Our study was performed using vowel samples from the voice disorder database recorded at the Massachusetts Eye and Ear Infirmary (MEEI) in1994. The KAYPENTAX company markets this database. Software development was conducted using MATLAB, a user-friendly programming language which has been applied widely for signal processing. An algorithm was developed to compute harmonic bandwidths for various speech samples of sustained vowel sounds. Open and closed tests were conducted on 23 samples of pathologic and normal speech samples each. Classification results showed 69.56% probability of correct detection of pathologic speech samples during an open test

Estimation of vocal tract shape trajectory using lossy Kelly-Lochbaum model

On esitetty teorioita, joiden mukaan puheen ymmärtämistä helpottaa aikaisempi kokemus puheen tuottamisesta. Muuntamalla akustinen puhesignaali hypoteesiksi puhujan artikulaatioeleistä voidaan saavuttaa puhujariippumattomampi ja äänteitä paremmin erotteleva kuvaus puheesta. Tämä työ esittelee metodin, jolla ääntöväylän liikeratoja voidaan arvioida suoraan puhesignaaleista. Tässä työssä luodaan Kelly-Lochbaum-tyyppinen ääntöväylämalli käyttäen apuna puheentuottamisen teoriaa. Malli on varustettu huulisäteilyllä ja säädettävällä huulten pituudella. Mallia käyttäen luodaan hakutaulukko, joka kuvaa vastaavuuksia puheen hetkellisten spektriominaisuuksien ja artikulatoristen muotojen välillä. Hakutaulukkoa voidaan käyttää mappaukseen akustisen ja artikulatorisen avaruuden välillä. Luotua mallia käytetään ääntöväylän liikeratojen arvioinnissa jatkuvan puheen aikana. Liikeradat löydetään käyttämällä yksinkertaista optimointialgoritmia, joka estimoi liikeradan minimoimalla artikulaatioon kuluvaa energiaa.There are theories that during speech perception, the understanding of speech is boosted by the knowledge of the articulatory gestures based on former speech production experience. By transforming an acoustic speech signal into a hypothesis about the articulatory gestures of the speaker, it is possible to obtain a more accurate, speaker-independent description of speech. This thesis introduces a method of estimating vocal tract trajectories from speech signals. Using the theory of speech production, a lossy Kelly-Lochbaum vocal tract model equipped with lip radiation impedance and variable lip rounding length is created. A lookup table consisting of correspondences between spectral qualities of instantaneous speech signals and articulatory shapes is created using this model. The lookup table can be used to perform acoustic-to-articulatory mapping. The obtained model is used in estimation of vocal tract shape trajectories in continuous speech. Smooth and minimum energy trajectories are found by using a simple optimization algorithm

Vowel coding using an articulatory model

An investigation into articulatory vocoding for vowels, as a means of achieving high quality coding at low bit rates, is carried out in this thesis. Methods of estimating the vocal tract transfer function from the speech wave are compared, and an algorithm for closed glottis interval (CGI) analysis is developed. CGI analysis is chosen over autocorrelation based inverse filtering methods. Various distortion measures for use in Vector Quantization are evaluated, and a new covariance distortion measure is proposed. It is shown that this measure yields close matches from an acoustic codebook. An articulatory coding system is designed, including a linked codebook of articulatory shapes, based on synthetic speech. A method of generating a similar codebook from real speech is proposed, and an investigation into estimating articulatory parameters from the speech wave is carried out to this end

Models and analysis of vocal emissions for biomedical applications: 5th International Workshop: December 13-15, 2007, Firenze, Italy

The MAVEBA Workshop proceedings, held on a biannual basis, collect the scientific papers presented both as oral and poster contributions, during the conference. The main subjects are: development of theoretical and mechanical models as an aid to the study of main phonatory dysfunctions, as well as the biomedical engineering methods for the analysis of voice signals and images, as a support to clinical diagnosis and classification of vocal pathologies. The Workshop has the sponsorship of: Ente Cassa Risparmio di Firenze, COST Action 2103, Biomedical Signal Processing and Control Journal (Elsevier Eds.), IEEE Biomedical Engineering Soc. Special Issues of International Journals have been, and will be, published, collecting selected papers from the conference