Discrimination of Pathological Voice Based on Acoustical Analysis

This paper presents some results of an acoustic analysis of the pathological voice and their clinical application in the diagnosis of voice disorders. The paper deals with three topics : (1) the acoustic parameters useful for describing the characteristics of the pathological voice (Chap. 2), (2) the relation between the acoustic parameters and the medical parameters relevant to diagnosis (Chap. 3), (3) the discrimination of the laryngeal diseases by use of acoustic parameters (Chap. 4). In Chap. 2 the method of acoustic analysis and the parameter extraction are described. The glottal sound waveforms were estimated from the speech wave and the parameters useful for representing the characteristics of the glottal sound were extracted. In Chap. 3 three groups of medical parameters are presented. They are (1) the parameters which describe the mode of vibration of the vocal folds, (2) the parameters which specify the vibration of vocal folds, and (3) the psychoacoustic parameters. The relation between each group of parameters and the acoustic parameters are discussed first by means of a simple correlation and then by means of a principal component analysis. The acoustic parameters can more effectively represent various phases of medical parameters when they are combined multidimensionally than when compared with one another. In Chap. 4 the result of a discrimination of four typical laryngeal diseases and a normal case is presented. The canonical analysis was applied to the 14 acoustic parameters. In this result, 84% of the normal cases were separated from the pathological cases, provided that the distribution of each group was Gaussian. And 84% of the cases of the laryngeal cancer were separated from the other three diseases. Among the remaining three diseases, that is, the recur-rent nerve paralysis, the vocal fold polyp and the sulcus vocalis, 70% of the cases were separated from each other.