Articulatory speech synthesizer
Year: 1996
Type: article
Abstract: The aim of this research was to gain more understanding about the unvoiced speech production mechanisms, and develop one solution to the excitation relocation problem for the vocally handicapped. A flexible and high quality articulatory speech synthesis tool called ARTM was developed to achieve this aim. The results of this study will be of interest to researchers in speech modeling, analysis, and synthesis.
Speech is generated when air is expelled from the lungs through the larynx, passed into the vocal cavities and finally, radiated at the mouth and nostrils. It can be roughly classified as either voiced sounds, fricatives or plosives. Since most portions of speech are voiced sounds, analyzing voiced sounds provides us with an understanding of the production of phonetic information and vocal characteristics. Numerous algorithms have been proposed and many of them give successful results for voiced speech. However, little effort has been devoted to the analysis of unvoiced speech. That is mainly because of the difficulty in analyzing unvoiced speech, which is characterized by its aperiodic characteristics. In spite of the technical difficulties, research for unvoiced speech is essential for various applications. One aspect of this research is to understand and investigate the factors relevant to the production of unvoiced speech.
The normal speaker routinely phonates using the vocal folds. Unfortunately, over 1.5 million nonspeaking persons in the USA, excluding some deaf individuals, can not phonate using the vocal folds. The vibratory pattern of the vocal folds is a major factor relating laryngeal function to the sound production. Imbalance of the vocal folds, an irregular shape of the vocal folds, and abnormal tissue properties are believed to contribute to abnormal vibratory patterns. In 1980, an electrically driven intraoral artificial larynx was invented. This new speech prosthesis consists of a small speaker (with battery) and a resonator horn, which are joined to a dental plate and placed in the oral cavity of the subject. With such a device the subject can produce intelligible but poor quality speech. Since this electrically driven speech prosthesis must be placed in the vocal tract, the other feature of this study is the derivation of a new form of the discrete-time acoustic equations with excitation in the vocal tract.
A flexible articulatory model was designed with special interfaces that provide numerical specification of parameters as well as sliding bar capabilities to allow parameter adjustments. Flanagan's acoustic model was considered the most appropriate for the time-domain articulatory synthesis. A transmission-line circuit model of the vocal system, which includes the vocal tract, the nasal tract with sinus cavities, the glottal impedance, the subglottal tract, the excitation source, and the turbulence noise source, was constructed, The acoustic equations of the vocal system were rederived for the proposed articulatory synthesizer. A digital time-domain approach was used to simulate the dynamic properties of the vocal system as well as to improve the quality of the synthesized speech.
Authors: Changshiann John Wu, D. G. Childers
Language: English
Topic: Voice and Speech Disorders
Subfield: Speech and Hearing
Field: Health Professions
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2269450587