Convergence in voice fundamental frequency during synchronous speech

Joint speech behaviours where speakers produce speech in unison are found in a variety of everyday settings, and have clinical relevance as a temporary fluency-enhancing technique for people who stutter. It is currently unknown whether such synchronisation of speech timing among two speakers is also accompanied by alignment in their vocal characteristics, for example in acoustic measures such as pitch. The current study investigated this by testing whether convergence in voice fundamental frequency (F0) between speakers could be demonstrated during synchronous speech. Sixty participants across two online experiments were audio recorded whilst reading a series of sentences, first on their own, and then in synchrony with another speaker (the accompanist) in a number of between-subject conditions. Experiment 1 demonstrated significant convergence in participants’ F0 to a pre-recorded accompanist voice, in the form of both upward (high F0 accompanist condition) and downward (low and extra-low F0 accompanist conditions) changes in F0. Experiment 2 demonstrated that such convergence was not seen during a visual synchronous speech condition, in which participants spoke in synchrony with silent video recordings of the accompanist. An audiovisual condition in which participants were able to both see and hear the accompanist in pre-recorded videos did not result in greater convergence in F0 compared to synchronisation with the pre-recorded voice alone. These findings suggest the need for models of speech motor control to incorporate interactions between self- and other-speech feedback during speech production, and suggest a novel hypothesis for the mechanisms underlying the fluency-enhancing effects of synchronous speech in people who stutter.

Can the Vocal Expression of Intellectually Disabled Individuals Be Used as a Pain Indicator? Initial Findings Supporting a Possible Novice Assessment Method

Pain is difficult to assess in non-verbal populations such as individuals with intellectual and developmental disability (IDD). Due to scarce research in this area, pain assessment for individuals with IDD is still lacking, leading to maltreatment. To improve medical care for individuals with IDD, immediate, reliable, easy to use pain detection methods should be developed. The goal of this preliminary study was to examine the sensitivity of acoustic features of vocal expressions in identifying pain for adults with IDD, assessing their feasibility as a pain detection indicator for those individuals. Such unique pain related vocal characteristics may be used to develop objective pain detection means. Adults with severe-profound IDD level (N = 9) were recorded in daily activities associated with pain (during diaper changes), or without pain (at rest). Spontaneous vocal expressions were acoustically analyzed to assess several voice characteristics. Analyzing the data revealed that pain related vocal expressions were characterized by significantly higher number of pulses and higher shimmer values relative to no-pain vocal expressions. Pain related productions were also characterized by longer duration, higher jitter and Cepstral Peak Prominence values, lower Harmonic-Noise Ratio, lower difference between the amplitude of the 1st and 2nd harmonic (corrected for vocal tract influence; H1H2c), and higher mean and standard deviation of voice fundamental frequency relative to no-pain related vocal productions, yet these findings were not statistically significant, possibly due to the small and heterogeneous sample. These initial results may prompt further research to explore the possibility to use pain related vocal output as an objective and easily identifiable indicator of pain in this population.

Synchronised speech and speech motor control: convergence in voice fundamental frequency during choral speech

Synchronised speech behaviours such as choral speech (speaking in unison) are found in a variety of everyday settings, and have clinical relevance as a temporary fluency-enhancing technique for people who stutter. It is currently unknown whether such synchronisation of speech timing among two speakers is also accompanied by alignment in their vocal characteristics, for example in acoustic measures such as pitch. The current study investigated this by testing whether convergence in voice fundamental frequency (F0) between speakers could be demonstrated during choral speech. Sixty participants across three online experiments were audio recorded whilst reading a series of sentences, first on their own, and then in synchrony with another speaker (the accompanist) in a number of between-subject conditions. Experiment 1 demonstrated significant convergence in participants’ F0 to a pre-recorded accompanist voice, in the form of both upward (high F0 accompanist condition) and downward (low F0 accompanist condition) changes in F0; however, upward convergence was greater than downward convergence. Experiment 2 found that downward convergent changes in F0 could not be increased by the use of an accompanist voice with an even lower F0. Experiment 3 demonstrated that such convergence was not seen during a visual choral speech condition, in which participants spoke in synchrony with silent video recordings of the accompanist. Further, convergence in F0 was enhanced for a condition where participants could both see and hear the accompanist in pre-recorded videos compared to synchronisation with the pre-recorded voice alone. These findings suggest the need for models of speech motor control to incorporate interactions between self- and other-speech feedback during speech production, and suggest a novel hypothesis for the mechanisms underlying the fluency-enhancing effects of choral speech in people who stutter.

Acoustic and Perceptual Characteristics of Mandarin Speech in Gay and Heterosexual Male Speakers

This study investigated acoustic and perceptual characteristics of Mandarin speech produced by gay and heterosexual male speakers. Acoustic analysis of monosyllabic words showed significant differences between the two groups in voice fundamental frequency (F0), F1 of low vowel, and duration of aspiration/frication in consonants. The acoustic patterns on F0, formants, and center of gravity as well as spectral skewness of /s/ differed from those reported for Western languages like American English, which could be interpreted from a sociopsychological point of view based on different acceptability of gay identity in the two societies. The results of a perceptual experiment revealed significant but weak correlations between the acoustic parameters and the score of perceived gayness, which was significantly higher on gay speech than on heterosexual male speech. Although the observed F0 and F1 patterns in Mandarin gay speech were opposite to the stereotype of gayness, gay identity can still be identified to some extent from speech due to the existence of other acoustic cues such as a longer fricative duration, which is not a stereotype of gayness but has been consistently observed in Mandarin and Western languages.

Auditory-Motor Perturbations of Voice Fundamental Frequency: Feedback Delay and Amplification

Purpose Gradual and sudden perturbations of vocal fundamental frequency ( f o ), also known as adaptive and reflexive f o perturbations, are techniques to study the influence of auditory feedback on voice f o control mechanisms. Previous vocal f o perturbations have incorporated varied setup-specific feedback delays and amplifications. Here, we investigated the effects of feedback delays (10–100 ms) and amplifications on both adaptive and reflexive f o perturbation paradigms, encapsulating the variability in equipment-specific delays (3–45 ms) and amplifications utilized in previous experiments. Method Responses to adaptive and reflexive f o perturbations were recorded in 24 typical speakers for four delay conditions (10, 40, 70, and 100 ms) or three amplification conditions (−10, +5, and +10 dB relative to microphone) in a counterbalanced order. Repeated-measures analyses of variance were carried out on the magnitude of f o responses to determine the effect of feedback condition. Results There was a statistically significant effect of the level of auditory feedback amplification on the response magnitude during adaptive f o perturbations, driven by the difference between +10- and −10-dB amplification conditions (hold phase difference: M = 38.3 cents, SD = 51.2 cents; after-effect phase: M = 66.1 cents, SD = 84.6 cents). No other statistically significant effects of condition were found for either paradigm. Conclusions Experimental equipment delays below 100 ms in behavioral paradigms do not affect the results of f o perturbation paradigms. As there is no statistically significant difference between the response magnitudes elicited by +5- and +10-dB auditory amplification conditions, this study is a confirmation that an auditory feedback amplification of +5 dB relative to microphone is sufficient to elicit robust compensatory responses for f o perturbation paradigms.

Differential causal involvement of human auditory and frontal cortices in vocal motor control

Speech motor control requires integration of sensory and motor information. Bidirectional communication between frontal and auditory cortices is crucial for speech production, self-monitoring and motor control. We used cortical direct electrical stimulation (DES) to functionally dissect audio-motor interactions underlying speech production and motor control. Eleven neurosurgical patients performed a visually cued vocal task in which a short auditory feedback perturbation was introduced during vocalization. We evaluated the effect of DES on vocal initiation, voice fundamental frequency (F0) and feedback-dependent motor control. DES of frontal sites modulated vocal onset latencies. Stimulation of different inferior frontal gyrus sites elicited either shortening or prolongation of vocal latencies. DES distinctly modulated voice F0 at different vocalization stages. Frontal and temporal areas played an important role in setting voice F0 in the first 250 ms of an utterance, while Heschls gyrus was involved later when auditory input is available for self-monitoring. Vocal responses to pitch-shifted auditory feedback were mostly reduced by DES of non-core auditory cortices. Overall, we demonstrate that vocal planning and initiation are driven by frontal cortices, while feedback-dependent control relies predominantly on non-core auditory cortices. Our findings represent direct evidence of the role played by different auditory and frontal regions in vocal motor control.

Effects of Fundamental Frequency, Vocal Intensity, Sample Duration, and Vowel Context in Cepstral and Spectral Measures of Dysphonic Voices

Purpose Smoothed cepstral peak prominence (CPPS) and harmonics-to-noise ratio (HNR) are acoustic measures related to the periodicity, harmonicity, and noise components of an acoustic signal. To date, there is little evidence about the advantages of CPPS over HNR in voice diagnostics. Recent studies indicate that voice fundamental frequency (F0) and intensity (sound pressure level [SPL]), sample duration (DUR), vowel context (speech vs. sustained phonation), and syllable stress (SS) may influence CPPS and HNR results. The scope of this work was to investigate the effects of voice F0 and SPL, DUR, SS, and token on CPPS and HNR in dysphonic voices. Method In this retrospective study, 27 Brazilian Portuguese speakers with voice disorders were investigated. Recordings of sustained vowels (SVs) /a:/ and manually extracted vowels (EVs) /a/ from Consensus Auditory-Perceptual Evaluation of Voice sentences were acoustically analyzed with the Praat program. Results There was a highly significant effect of F0, SPL, and DUR on both CPPS and HNR ( p < .001), whereas SS and vowel context significantly affected CPPS only ( p < .05). Higher SPL, F0, and lower DUR were related to higher CPPS and HNR. SVs moderately-to-highly correlated with EVs for CPPS, whereas HNR had few and moderate correlations. In addition, CPPS and HNR highly correlated in SVs and seven EVs ( p < .05). Conclusion Speaking prosodic variations of F0, SPL, and DUR influenced both CPPS and HNR measures and led to acoustic differences between sustained and excised vowels, especially in CPPS. Vowel context, prosodic factors, and token type should be controlled for in clinical acoustic voice assessment.