Effect of linguistic context on the perception of consonants in Parkinsonian Read French speech.

We examined the effect of linguistic factors on the perceptual identification of intervocalic consonants produced by speakers with Parkinson's Diseases (PD). To neutralize the effect of preceding and following contexts, all the intervocalic consonants were excised with half the preceding and following vowels.We recorded 10 PD and 10 healthy speakers reading a text. An average of 114 VCV sequences per speaker was obtained. In total, our corpus consisted of 2280 stimuli. For the perception test, 20 adults native speakers of French were instructed that they would be presented utterances produced by different speakers and that they were to identify the sequences and write what they heard. No information was given on the sequence type (VCV).The reported consonant was examined in relation to the intended consonant; the score of distorsion was the number of phonetic features differing from the prototypical consonant. The results were examined as a function of the following/or preceding linguistic factors: consonant nature, oral/nasal vocalic context, class of word (function or content) and prosodic position within sentences.Consonant imprecision was confirmed in the speech of PD speakers. Two groups of patients were observed: the former with a low degree of dysarthria severity and scores of consonant identification close to that of healthy speakers; the latter with a high degree of dysarthria severity and a low identification score.Linguistic factors were shown to affect consonant production and perception. In both normal and PD speech, consonants had more features identified when they belonged to content words, word-initial syllables or final-phrase syllables. This suggests that in Parkinson's disease speech disorders relate to motor control and not to a loss of the linguistic knowledge.

[The effect of time-compressed speech on the perception of ataxic dysarthria: a report of two cases]. / Effet de l'accélération artificielle du signal de parole sur la perception des dysarthries cérébelleuses: à propos de deux cas.

AIM: In cerebellar dysarthria, the lack of precision in the articulatory motions leads to a temporal dysregulation with a decreased rate of speech. That is, our hypothesis is that the signal distortions are linked to the slowness of speech and that the acceleration of the rate improves the intelligibility of speech. PATIENTS AND METHOD: Two patients with a cerebellar pathology and an ataxic dysarthria participated in the present study. Speech intelligibility was assessed subjectively by a visual analog scale, and objectively by the constant-stimulus method associated with an identification task of a target phoneme in real time. The SOLA algorithm was used to accelerate the speech stimuli. 144 test sentences were created at 3 speed rates: 48 sentences at 'natural speed' (without compression, VN), 48 sentences at 'intermediate speed' (50% of the maximum rate, VI) and 48 sentences at 'maximum speed' (mean rate of a control group of speakers, VM). The 144 test sentences, in 3 experimental conditions, were distributed over 3 lists, each listener hearing each sentence only once; 8 subjects were assigned to each list. The sentences were presented in random order. A subjective assessment was performed for the whole corpus. The statistical analysis was performed with a mixed logit model for the subjective scores and the reaction time and with a chi2 test for the errors. RESULTS: For each patient, the odds of an improved intelligibility were significantly greater for the VI or VM condition than for the VN condition. The effect tended to be stronger for patient Z. From the VN to the VI condition, the satisfaction rate regarding the intelligibility increased from 78 to 87% for patient B and from 46 to 63% for patient Z (p = 0.03). There were fewer errors for the accelerated speech for patient Z. The acceleration had no effect on the reaction times in the phoneme identification task (F 2,(1,024) = 2.14, p = 0.12). CONCLUSIONS: In 2 cases of ataxic dysarthria, the perceived intelligibility was improved by a temporal acceleration of the speech disorders.

Final lengthening in Parkinsonian French speech: effects of position in phrase on the duration of CV syllables and speech segments.

This study had two objectives. The first was to analyse the impact of Parkinson's disease (PD) on the duration of CV syllables and their components in different positions within phrases in French; the second was to examine the distribution of final lengthening (FL) on syllable sub-components. Two main tendencies emerged: (1) PD patients produced normal FL, and (2) FL influenced vowels more than consonants. These findings suggest that PD speakers had no difficulty with FL and that there is a progressive lengthening across the sub-constituents of the final syllable. More fundamentally, these results indicate that the syntactic function of prosody is intact in PD patients, at least during the early and mild stages of the disease.

Segmental duration in Parkinsonian French speech.

OBJECTIVES: The present study had 2 main objectives: (1) examine the effect of Parkinson's disease (PD) on vowel and consonant duration in French read speech and (2) investigate whether the durational contrasts of consonants and vowels are maintained or compromised. RESULTS: The data indicated that the consonant durations were shortened in Parkinsonian speech (PS), compared to control speech (CS). However, this shortening was consonant dependent: unvoiced occlusives and fricatives were significantly shortened compared to other consonant categories. All vowels were slightly longer in PS than in CS, however, the observed differences were below the level of significance. Despite significant shortening of some consonant categories, the general pattern of intrinsic duration was maintained in PS. There was slightly less agreement for vowels with the normal contrast of intrinsic durations, possibly because vowel durational contrasts are more sensitive to PD disorders. CONCLUSION: Most PD patients tended to maintain the intrinsic duration contrasts of both vowels and consonants, suggesting that low-level articulatory constraints operate in a similar way and with the same weight in PS and CS.