Journal of Phonetics (1986) 14, 495-499 Session 6 Vocal fold disorder evaluation by digital speech analysis Germana Banci Department of Internal Medicine , Medical Physics Lab. , II University of Rome, 00173 Rome, Italy Simonetta Monini I Clinic O.R.L., Policlinic Umberto I, 00161 Rome, Italy Alessandro Falaschi and Nicolo De Sario Ugo Bordoni Foundation, 00144 Rome, Italy By means of digital processing of vocal signals we have automatically extracted some quantitative meaningful features which are related to vibratory pattern perturbations of the vocal folds, when affected by pathological processes. Here we give the methods and techniques of vocal signal analysis and the procedure for the evaluation, in a multidimensional space, of the parameters extracted, to estimate their capability of discrimination between the normal and pathologic classes. 1. Introduction Since the appearance of the acoustic theory of speech production (Fant, 1960), the voice acoustic analysis for diagnostic purposes has appeared to be a promising aid for the traditional methods for the diagnosis of laryngeal pathologies, based mainly on visual inspection of the larynx and on auditory and perceptual evaluation of the voice of the patient. Later, by the application of new techniques of digital speech analysis, some methods (still at experimental level) were developed, aimed at the automatic detection of laryngeal pathologies through the extraction of several quantitative features. These features represent some characteristic aspects present in pathological voices due to vocal fold diseases; for instance, the alteration of the spectral structure, abnormal noise, pitch perturbations and periodicity loss (Hecker & Kreul, 1971 ; Davis, 1976; Koike, Taka- hashi & Calcaterra, 1977; Horii, 1980; Kitajima, 1981; Gubrynowicz, Kacprowski, Mikiel & Zarnecki, 1981 ; Laver, Hiller & Hanson, 1982; Kim, Kakita & Hirano, 1982). In this work, which is the continuation and integration of a previous study, after having recalled the techniques and methods for the extraction of some physiologically meaningful parameters related to vocal fold disfunctions and alterations, we propose a statistical method for the evaluation of the feature "effectiveness" in a multidimensional 0095-4470/ 86/030495 + 05 $03.00/0 © 1986 Academic Press Inc. (London) Ltd.