Victor J. Boucher

Timing relations in speech and the identification of voice-onset times: A stable perceptual boundary for voicing categories across speaking rates

This study shows that the ratio of voice onset time (VOT) to syllable duration for /t/ and /d/ presentsDistributions with a stable boundary across speaking rates and that this boundary constitutes a perceptual criterion by which listeners judge the category affiliation of VOT. In Experiment 1, best-fit regression lines for VOT ratios of intervocalic /t/ and /d/ against speaking rate had zero slopes, and there was an inferable boundary between the distributions. In Experiment 2, listeners’ identifications of syllable-initial stops conformed to this boundary ratio. In Experiment 3, VOT was held constant,while VOT ratios were altered by modifying the duration of the following vowel. As VOT ratios exceeded the boundary estimated from the data of Experiment 1, listeners’ identifications shifted from /d/ to /t/. Timing relations in speech production can determine the identification of voicing categoriesacross speaking rates.

Physiologic Features of Vocal Fatigue: Electromyographic Spectral-Compression in Laryngeal Muscles

Objectives: This study addresses the problem of defining observable attributes of “vocal fatigue” as a physiologic condition. The aim was to determine the applicability of electromyography (EMG) spectral compression in observing fatigue in laryngeal muscles arising from prolonged vocal effort.

On the Function of Stress Rhythms in Speech: Evidence of a Link with Grouping Effects on Serial Memory.

Language learning requires a capacity to recall novel series of speech sounds. Research shows that prosodic marks create grouping effects enhancing serial recall. However, any restriction on memory affecting the reproduction of prosody would limit the set of patterns that could be learned and subsequently used in speech. By implication, grouping effects of prosody would also be limited to reproducible patterns. This view of the role of prosody and the contribution of memory processes in the organization of prosodic patterns is examined by evaluating the correspondence between a reported tendency to restrict stress intervals in speech and size limits on stress-grouping effects. French speech is used where stress defines the endpoints of groups. In Experiment 1, 40 speakers recalled novel series of syllables containing stress-groups of varying size. Recall was not enhanced by groupings exceeding four syllables, which corresponded to a restriction on the reproducibility of stress-groups. In Experiment 2, the subjects produced given sentences containing phrases of differing length. The results show a strong tendency to insert stress within phrases that exceed four syllables. Since prosody can arise in the recall of syntactically unstructured lists, the results offer initial support for viewing memory processes as a factor of stress-rhythm organization.

Perceptual chunking and its effect on memory in speech processing: ERP and behavioral evidence

We examined how perceptual chunks of varying size in utterances can influence immediate memory of heard items (monosyllabic words). Using behavioral measures and event-related potentials (N400) we evaluated the quality of the memory trace for targets taken from perceived temporal groups (TGs) of three and four items. Variations in the amplitude of the N400 showed a better memory trace for items presented in TGs of three compared to those in groups of four. Analyses of behavioral responses along with P300 components also revealed effects of chunk position in the utterance. This is the first study to measure the online effects of perceptual chunks on the memory trace of spoken items. Taken together, the N400 and P300 responses demonstrate that the perceptual chunking of speech facilitates information buffering and a processing on a chunk-by-chunk basis.

The ecology of self-monitoring effects on memory of verbal productions: Does speaking to someone make a difference?

Experiments involving verbal self-monitoring show that memory for spoken words varies with types of sensory feedback: memory is better when words are spoken aloud than when they are lip-synched or covertly produced. Such effects can be explained by the Central Monitoring Theory (CMT) via a process that matches a forward model reflecting expected sensory effects of practiced forms and sensory information during speech. But CMT oversees factors of shared attention as achieved by speaker-listener gaze, and implies that sensory feedback may not affect the learning of unpracticed forms (non-words). These aspects of CMT were examined in two experiments of self-monitoring focusing on oro-sensory feedback. In Experiment 1 we show that varying feedback creates differential effects on memory for spoken words and that speaker-listener gaze alters these effects. Using non-words, Experiment 2 shows the absence of differential feedback effects. The results confirm CMT but suggest the need to refine the theory in terms of processes that mediate attention.

Size‐constraints on intonation groups in speech: Evidence of an independent syllable‐count principle

This poster examines size‐limits on intonation (F0) contours in spontaneous speech and presents the results of an experiment on a syllable‐count principle, which is seen to constitute, irrespective of syntax, a factor restricting the length of F0 groups. Studies of various languages indicate a general tendency to restrict stress‐groups in speech to four syllables or less. In languages were stress is not lexically coded (e.g., French), syntax is not a sufficient predictor of stress. The object was to determine whether these aspects of stress patterning also apply to tonal groups. Statistics are lacking with respect to the extent of F0 contours in speech. Pitch‐extracting software was used to analyze the speech of 15 native speakers of French (20 minutes each). Initial results suggest an eight‐syllable limit on tonal groups. Based on these statistics an experiment was conducted where 40 Ss read and repeated visually presented sentences containing major syntactic divisions (phrase boundaries) at different lo...

Intrinsic factors of releasing motions in an articulator: On assuming segmental input in speech‐production models

Prominent models of speech production use serial input that is assumed to be commensurate with linguistic segments. The view is that such units underlie a serial activation of aperture motions such as closing and opening motions of the lips in articulating a bilabial stop. This is incompatible with conventional EMG observations showing a single burst of activity of labial adductors at the onset of a close‐open cycle. The present study examines the spring‐like effects of bilabial compression and pressure on labial opening (release) following a relaxation of the orbicularis oris muscle. Using reiterative series [papapapa] produced at increasing intensities, the range and velocity of opening motions of the lower‐lip were correlated with lip compression and oral‐pressure. The results for three speakers show that pressure and compression are correlated and that these factors account for 45% to 66% of the variance in velocity of lower‐lip opening, and for 47% to 73% of the variance in the range of lower‐lip ope...

On the link between the ability to reproduce rhythm and reading speed: Effects of visual grouping marks

Studies have revealed a link between a deficient ability to reproduce rhythm and dyslexia. Moreover, a normal ability to reproduce rhythm has been shown to correlate with reading speed. Some associate these findings to effects of neural oscillations and a visual parsing of text input (Vidyasagar, 2013). The present study aimed to clarify the properties of the visual stimuli that support a correlation between rhythm reproduction and reading speed. The experiments were partly based on Tierney and Kraus (2014). Thirty participants were asked to reproduce heard regular (2 beats/sec) and irregular (1-3 beats/sec) rhythms by tapping on a keyboard. Then, the participants had to read out loud, at a fast rate, visually displayed sequences of words and non-words. The sequences contained either no spaces between items (baseline condition) or spaces marking regular and irregular groups. Mean reading speeds were calculated on accurately decoded sequences. Among the significant findings, strong correlations were observ...

Effects of the growth of breath capacities on mean length of utterances: How maturing production processes influence indices of language development

Abstract Measures of “mean length of utterance” (MLU) involving morpheme counts in transcripts are widely applied to speakers of all ages and are generally interpreted as an index of developing grammar. Yet no study has examined how the growth of respiratory capacities influences MLU and numbers of forms in utterances. We review longstanding problems of MLU counts and investigate the effects of growing breath capacities using speech samples and measures of vital capacity (VC) of 50 speakers aged 5 to 27 years. The results show that VC correlates strongly with MLU, which associates with rising numbers of long lexemes. This suggests that, in normal development, the growth of VC offers the possibility of producing increasingly long utterances that can influence lexical diversity. Hence, interpreting MLU and co-varying indices of lexical development requires a consideration of the effects of maturing production processes in a perspective where developing speech and language are seen to intertwine.

Using criterio voice familiarity to augment the accuracy of speaker identification in voice lineups

Voice familiarity is a principal factor underlying the apparent superiority of human-based vs machine-based speaker identification. Our study evaluates the effects of voice familiarity on speaker identification in voice lineups by using a Familiarity Index that considers (1) recency (the time of last spoken contact), (2) duration of spoken contact, and (3) frequency of spoken contact. Three separate voice-lineups were designed each containing ten male voices with one target voice that was more or less familiar to individual listeners (13 per lineup, n = 39 listeners in all). The stimuli consisted in several verbal expressions varying in length, all of which reflected a similar dialect and the voices presented a similar speaking fundamental frequency to within one semitone. The main results showed high rates of correct target voice identification across lineups (>99%) when listeners were presented with voices that were highly familiar in terms of all three indices of recency, duration of contact, and frequ...