Article révisé par les pairs
| Résumé : | Jitter measures are known to discriminate between normal and dysphonic speakers. We investigated the influence of (i) speech material type (i.e. sustained vowels vs. isolated sentences); (ii) phonetic vowel quality; (iii) preprocessing; and (iv) speaker sex on the discriminatory performance of two pitch perturbation measures. The aim was to learn about the influence of experimental conditions on the output of dysphonic voice analysis systems. Two comparative studies were carried out. The first showed that as far as inter-vowel quality differences were concerned, all significant differences could be related to the idiosyncratic behaviour of several preprocessing schemes with reference to vowel quality. Intrinsic differences were canceled out by normalizing absolute jitter by the average fundamental period. As a rule of thumb preprocessing routines were more successful, the further F0 and F1 were apart. With all other experimental factors held constant, significant differences persisted between several preprocessing schemes, e.g. analysis by linear prediction failed on female voices and low-pass filtering eliminated so much fine signal details that discrimination between normal and dysphonic voices became impossible. In a second experiment, jitter values extracted from connected speech did not discriminate between normal and dysphonic speakers any more efficiently than values calculated from sustained vowels. As far as our corpora were concerned, no intrinsic superiority in the discrimination performance of connected speech as opposed to sustained vowels could be found. In the case of running speech absolute microperturbation values appeared to be higher during inter-segment transitions and during voice onset and offset. © 1989. |
