Synthesis of severely pathological voices

In this paper, the acoustic and perceptual correlates of bicyclic, rough/breathy, rough/bicyclic, strained/breathy, and breathy/bicyclic, are studied. The work represents a continuation of a previous study [J. Acoust. Soc. Am. 94, 1782 (A) (1993)]. An analysis-by-synthesis approach is used, utilizing KLSYN88, to study ten speech waveforms obtained from the VA Hospital in West LA. Preliminary results indicate the synthesizer’s diplophonia parameter (DI) is useful in synthesizing bicyclic voices. Other severe disorders can be synthesized in one of three ways: (1) simultaneous and equal use of parameters needed to synthesize milder cases of pathologies; for example, rough/breathy voices are synthesized with a time-varying F0, characteristic of rough voices, in combination with a high amplitude of aspiration noise, needed for breathiness perception, (2) increased use of a single set of parameters appropriate for a milder pathology; for example, a rough/bicyclic voice is synthesized with a time-varying F0 and very little DI, and (3) sequential use of parameters appropriate for two different qualities; for example, the synthesis of a strained/breathy voice requires varying the open-quotient parameter in time to match the acoustic and perceptual correlates of breathiness in one time interval and those of the strained quality in the other. These results will be discussed in terms of the independence, or otherwise correlation, of acoustic and perceptual features.