The main goal of this study is to validate the thesis, that the electroglottography (EGG), an nonivasive method of investigating of laryngeal behaviour, conveys essential information about glottal activity. This study provides a objective, computer-supported method of EGG signal description which can be used for the automatic determination of voice quality for normal and pathological speakers and in determination of laryngeal settings used for linguistic purposes.
In chapter I the concept of voice quality is described. The role of the voice quality in layered model of human communication is explained and basic issues of voice production are given. A qualitative description of voice quality, its relation to phonation type and schemes used in its labelling are presented. The quantitative methods used in investigation of laryngeal behaviour are presented, especially an inverse filtering (the leading method of objective measurement of glottal airflow).
Chapter II deals with the electroglottography. The principles of device functioning, relations between the EGG waveform and mode of vocal fold vibration are presented. Review of the literature on use of EGG in voice quality investigations is given and confronted with the proposed description of the EGG waveform.
In chapter III an experiment is described in which EGG-based measurements of voice quality are related to the categories of linguistic stress and pitch accent in German. The results exhibit a clear distinction in EGG waveforms due to stress factor and corresponds well with acoustic measurements of voice quality.
Chapter IV presents an application of proposed EGG waveform description to distinguish voice quality distortion caused by neurological and organic speech impairments. The results show that the EGG waveforms can be used to distingusih the voicve qualities of group of patients.
Chapter V reports a computer simulation of the EGG signal. The two-mass model of vocal folds vibration is used to simulate the EGG waveform. The effects of subglottal pressure and tension of the vocal folds on the EGG waveform are investigated and related to the results of the experiment reported in chapter III. A good accordance between theory and practise has been established, thus validating a practical use of the proposed EGG description of the EGG waveform.
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