We investigated the independent contribution of speech rate and speech rhythm to perceived foreign accent. To address this issue we used a resynthesis technique that allows neutralizing segmental and tonal idiosyncrasies between identical sentences produced by French learners of English at different proficiency levels and maintaining the idiosyncrasies pertaining to prosodic timing patterns. We created stimuli that 1) preserved the idiosyncrasies in speech rhythm while controlling for the differences in speech rate between the utterances; 2) preserved the idiosyncrasies in speech rate while controlling for the differences in speech rhythm between the utterances; 3) preserved the idiosyncrasies both in speech rate and speech rhythm. All the stimuli were created in intoned (with imposed intonational contour) and flat (with monotonized, constant F0) conditions. The original and the resynthesized sentences were rated by native speakers of English for degree of foreign accent.We found that both speech rate and speech rhythm influence the degree of perceived foreign accent, but the effect of speech rhythm is larger than that of rate. We also found that intonation enhances the perception of fine differences in rhythmic patterns but reduces the perceptual salience of fine differences in speech rate.

Purpose Previous studies have investigated the effects of the inability to produce hand gestures on speakers' prosodic features of speech; however, the potential effects of encouraging speakers to gesture have received less attention, especially in naturalistic settings. This study aims at investigating the effects of encouraging the production of hand gestures on the following speech correlates: speech discourse length (number of words and discourse length in seconds), disfluencies (filled pauses, self-corrections, repetitions, insertions, interruptions, speech rate), and prosodic properties (measures of fundamental frequency [F0] and intensity). Method Twenty native Italian speakers took part in a narration task in which they had to describe the content of short comic strips to a confederate listener in 1 of the following 2 conditions: (a) nonencouraging condition (N), that is, no instructions about gesturing were given, and (b) encouraging condition (E), that is, the participants were instructed to gesture while telling the story. Results Instructing speakers to gesture led effectively to higher gesture rate and salience. Significant differences were found for (a) discourse length (e.g., the narratives had more words in E than in N) and (b) acoustic measures (F0 maximum, maximum intensity, and mean intensity metrics were higher in E than in N). Conclusion The study shows that asking speakers to use their hands while describing a story can have an effect on narration length and can also impact on F0 and intensity metrics. By showing that enhancing the gesture stream could affect speech prosody, this study provides further evidence that gestures and prosody interact in the process of speech production.

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Previous studies have investigated the effects of the inability to make hand gestures on speakers' fluency; however, the question of whether encouraging speakers to gesture affects their fluency has received little attention. This study investigates the effect of restraining (Experiment 1) and encouraging (Experiment 2) hand gestures on the following correlates of speech: speech discourse length (number of words and discourse length in seconds), disfluencies (filled pauses, self-corrections, repetitions, insertions, interruptions, silent pauses), and acoustic properties (speech rate, measures of intensity and pitch). In two experiments, 10 native speakers of Italian took part in a narration task where they were asked to describe comic strips. Each experiment compared two conditions. In Experiment 1, subjects first received no instructions as to how to behave when narrating. Then they were told to sit on their hands while speaking. In Experiment 2, subjects first received no instructions and were then actively encouraged to use hand gestures. The results showed that restraining gestures leads to quieter and slower paced speech, while encouraging gestures triggers longer speech discourse, faster speech rate and more fluent and louder speech. Thus, both restraining and encouraging hand gestures seem to clearly affect prosodic properties of speech, particularly speech fluency.

Experimental studies on different languages have shown that neurogenetic disorders connected with Parkinson's disease (PD) determine a series of variations in the speech rhythm. This study aims at verifying whether the speech of PD patients presents rhythmic abnormalities compared to healthy speakers also in Italian. The read speech of 15 healthy speakers and of 11 patients with mild PD was segmented in consonantal and vocalic portions. After extracting the durations of all segments, the vowel percentage (%V) and the interval between two consecutive vowel onset points (VtoV) were calculated. The results show that %V has significantly different values in mildly affected patients as compared to controls. For Italian, %V spans between 44% and 50% for healthy subjects and between 51% and 58% for PD subjects. A positive correlation was found between %V and the number of years of PD since its insurgence. The correlation with the age at which the disease insurges is weak. With regard to VtoV, PD subjects do not speak at a significantly slower rate than healthy controls, though a trend in this direction was found. The data suggest that %V could be used as a more reliable parameter for the early diagnosis of PD than speech rate. AbstractExperimental studies on different languages have shown that neurogenetic disorders connected with Parkinson's disease (PD) determine a series of variations in the speech rhythm. This study aims at verifying whether the speech of PD patients presents rhythmic abnormalities compared to healthy speakers also in Italian. The read speech of 15 healthy speakers and of 11 patients with mild PD was segmented in consonantal and vocalic portions. After extracting the durations of all segments, the vowel percentage (%V) and the interval between two consecutive vowel onset points (VtoV) were calculated. The results show that %V has significantly different values in mildly affected patients as compared to controls. For Italian, %V spans between 44% and 50% for healthy subjects and between 51% and 58% for PD subjects. A positive correlation was found between %V and the number of years of PD since its insurgence. The correlation with the age at which the disease insurges is weak. With regard to VtoV, PD subjects do not speak at a significantly slower rate than healthy controls, though a trend in this direction was found. The data suggest that %V could be used as a more reliable parameter for the early diagnosis of PD than speech rate.