Fast Speech Rate Research Articles

Aerodynamic reduction in American English flapping

Are all tongue tip gestures for /t,d/ the same? Acoustic and articulatory studies have revealed that /t,d’s show a gradient behavior, in which invariancy is nonexistent. These results undermine phonological rules which represent leniting processes, such as flapping, as a rule where /t,d/ is replaced by an invariant flap. Adding to more evidence for gradiency, an aerodynamic experiment was designed to investigate the nature of alveolar tongue tip gestures, specifically in flapping contexts. Three native speakers of American English were recruited and each yielded 200 tokens, which contained medial /t,d/ in different phonetic contexts (stressed-syllable onset, unstressed-syllable onset, n+/t,d/, l+/t,d/ and r+/t,d/) and in two speaking rates. For each target consonant, duration ratio and airflow rate were obtained. In general, both duration ratio and airflow rate showed gradiency across rate and context. Tokens at a normal speech rate yielded higher ratios and airflow rates than tokens at a faster speech rate. However, rate did not affect each context equally. Accordingly, /t,d’s reveal a gradient behavior which ranges from a canonical stop to complete deletion.

The Perception of Syllable Affiliation of Singleton Stops in Repetitive Speech

Stetson (1951) noted that repeating singleton coda consonants at fast speech rates makes them be perceived as onset consonants affiliated with a following vowel. The current study documents the perception of rate-induced resyllabification, as well as what temporal properties give rise to the perception of syllable affiliation. Stimuli were extracted from a previous study of repeated stop + vowel and vowel + stop syllables (de Jong, 2001a, 2001b). Forced-choice identification tasks show that slow repetitions are clearly distinguished. As speakers increase rate, they reach a point after which listeners disagree as to the affiliation of the stop. This pattern is found for voiced and voiceless consonants using different stimulus extraction techniques. Acoustic models of the identifications indicate that the sudden shift in syllabification occurs with the loss of an acoustic hiatus between successive syllables. Acoustic models of the fast rate identifications indicate various other qualities, such as consonant voicing, affect the probability that the consonants will be perceived as onsets. These results indicate a model of syllabic affiliation where specific juncture-marking aspects of the signal dominate parsing, and in their absence other differences provide additional, weaker cues to syllabic affiliation.

Emotion-related effects of speech rate and rising vs. falling background music melody during audio news: the moderating influence of personality

We examined the personality-related differences in people’s emotional and other responses to news messages with a slow vs. a fast speech rate and a rising vs. a falling background music melody. Personality was measured with the Behavioural Inhibition System (BIS)/Behavioural Activation System (BAS) scales and the Zuckerman–Kuhlman Personality Questionnaire. Physiological parameters studied were electrodermal activity (EDA), pulse transit time, and interbeat intervals. Several findings consistent with the similarity-attraction theory emerged. For example, subjects scoring high on the BAS, Activity, and Aggression-Hostility dimensions reacted more positively to the news with a fast compared to a slow speech rate. The rising-melody news also elicited higher EDA than the falling-melody news among high BAS scorers. The results suggest that users may be attracted to media messages with audio characteristics manifesting emotions or a personality similar to their own.

Perceptual rate normalization in naturally produced bilabial stops

The perception of voicing categories is affected by the speaking rate, so that listeners’ category boundaries on a VOT continuum shift to a lower value when the syllable duration decreases (Miller and Volaitis, 1989; Volaitis and Miller, 1992). Previous rate normalization effects have been found using computer-generated stimuli. This study examines the effect of speech rate on voicing categorization in naturally produced speech. Four native speakers of American English repeated syllables (/bi/ and /pi/) at increasing rates in time with a metronome. Three-syllable stimuli were spliced from the repetitive speech. These stimuli contained natural decreases in VOT with faster speech rates. Besides, this rate effect on VOT was larger for /p/ than /b/, so that VOT values for /b/ and /p/ overlapped at the fastest rates. Eighteen native listeners of American English were presented with 168 stimuli and asked to identify the consonant. Perceptual category boundaries occur at VOT values 15 ms shorter than the values reported for synthesized stimuli. This difference may be due to the extraordinarily wide range of VOT values in previous studies. The values found in the current study closely match the actual division point for /b/ and /p/. The underlying mechanism of perceptual normalization will be discussed.

Self-reported efficacy of an all in-the-ear-canal prosthetic device to inhibit stuttering during one hundred hours of university teaching: an autobiographical clinical commentary

This manuscript outlines the lifelong battle with severe stuttering and describes a new modality of effective amelioration of the disorder from the standpoint of a university professor and researcher in the field of stuttering. Childhood reactions to stuttering are discussed, along with the educational and vocational impact of stuttering. Ongoing therapy was received throughout the formative years and into adulthood, emphasizing reduced rates of speech. The use of Delayed Auditory Feedback (DAF) was found to induce fluent speech, but was considered only as a tool for decreasing the speech rate to achieve fluency. When fluency under DAF was discovered to be possible at faster speech rates, the possibility that the use of DAF and other forms of altered auditory feedback could themselves have an inhibitory effect on stuttering, without concomitant rate reduction was investigated. An In-The-Canal (ITC) fluency-enhancing device was used that provided DAF and Frequency Altered Feedback (FAF) to produce more fluent speech. After 10 months of use, the author was relatively free from stuttering. Speech was natural sounding, relatively spontaneous and unlaboured with an absence of fear. However, further testing (that is currently underway at various centres) is necessary before generalizations can be made.

Self-reported efficacy of an all in-the-ear-canal prosthetic device to inhibit stuttering during one hundred hours of university teaching: an autobiographical clinical commentary

This manuscript outlines the lifelong battle with severe stuttering and describes a new modality of effective amelioration of the disorder from the standpoint of a university professor and researcher in the field of stuttering. Childhood reactions to stuttering are discussed, along with the educational and vocational impact of stuttering. Ongoing therapy was received throughout the formative years and into adulthood, emphasizing reduced rates of speech. The use of Delayed Auditory Feedback (DAF) was found to induce fluent speech, but was considered only as a tool for decreasing the speech rate to achieve fluency. When fluency under DAF was discovered to be possible at faster speech rates, the possibility that the use of DAF and other forms of altered auditory feedback could themselves have an inhibitory effect on stuttering, without concomitant rate reduction was investigated. An In-The-Canal (ITC) fluency-enhancing device was used that provided DAF and Frequency Altered Feedback (FAF) to produce more fluent speech. After 10 months of use, the author was relatively free from stuttering. Speech was natural sounding, relatively spontaneous and unlaboured with an absence of fear. However, further testing (that is currently underway at various centres) is necessary before generalizations can be made.

Word-level intelligibility of time-compressed speech: prosodic and segmental factors

In this study we investigate whether speakers, in line with the predictions of the Hyper- and Hypospeech theory, speed up most during the least informative parts and less during the more informative parts, when they are asked to speak faster. We expected listeners to benefit from these changes in timing, and our main goal was to find out whether making the temporal organisation of artificially time-compressed speech more like that of natural fast speech would improve intelligibility over linear time compression. Our production study showed that speakers reduce unstressed syllables more than stressed syllables, thereby making the prosodic pattern more pronounced. We extrapolated fast speech timing to even faster rates because we expected that the more salient prosodic pattern could be exploited in difficult listening situations. However, at very fast speech rates, applying fast speech timing worsens intelligibility. We argue that the non-uniform way of speeding up may not be due to an underlying communicative principle, but may result from speakers’ inability to speed up otherwise. As both prosodic and segmental information contribute to word recognition, we conclude that extrapolating fast speech timing to extremely fast rates distorts this balance between prosodic and segmental information.

Contribution of speech rate to speech perception in multichannel cochlear implant users.

This study describes the effect of speech rate (fast, 11 syllables per second; medium, 9 syllables per second; slow, 6 syllables per second) on speech perception in 10 cochlear implant users. The speech perception performance was evaluated on the basis of the percentage score of syllables that were correctly recalled in sentences composed of 4 to 6 words. The percentage scores at the fast, medium, and slow speech rates were 15.7%, 39.0%, and 56.0%, respectively. The effect of speech rate slowing was significant (p < .0001). Variations in the effect of speech rate slowing were observed in the cochlear implant users. The improvement of speech perception by speech rate slowing was significantly (p < .005) related to the word test score and the score at the fast speech rate. The results reveal that the rate of speech is an important factor in improving the speech perception of cochlear implant users.

Effect of delayed auditory feedback on normal speakers at two speech rates.

This study investigated the effect of short and long auditory feedback delays at two speech rates with normal speakers. Seventeen participants spoke under delayed auditory feedback (DAF) at 0, 25, 50, and 200 ms at normal and fast rates of speech. Significantly two to three times more dysfluencies were displayed at 200 ms (p<0.05) relative to no delay or the shorter delays. There were significantly more dysfluencies observed at the fast rate of speech (p = 0.028). These findings implicate the peripheral feedback system(s) of fluent speakers for the disruptive effects of DAF on normal speech production at long auditory feedback delays. Considering the contrast in fluency/dysfluency exhibited between normal speakers and those who stutter at short and long delays, it appears that speech disruption of normal speakers under DAF is a poor analog of stuttering.

The effect of fast speech rate on stuttering frequency during delayed auditory feedback

Delayed auditory feedback (DAF) has been documented to improve fluency in those who stutter. The increased fluency has been attributed to the slowed speech rate induced by DAF, but recent experiments have suggested that increasing the speech rate may also decrease stuttering under DAF. This investigation described the effect of combining a fast speech rate and DAF on the fluency of four people who stutter. Fluency of the two mildly dysfluent subjects was the same for both no DAF and DAF conditions at normal and at fast oral reading rates. In contrast, the two severely dysfluent subjects improved in fluency from the no DAF to the DAF conditions. They were found to be dysfluent at both normal and fast oral reading rates without DAF. The results of the study point to the need for further research on the relationship between speech rate and stuttering frequency under conditions of DAF and no DAF. Educational objectives: Readers will learn about and be able to describe how the frequency of stuttering is affected by: (1) speech rates; (2) DAF; and (3) how stuttering severity influences such effects.

Rate-induced resyllabification revisited.

This paper presents the results of a rate scaling speech production experiment which seeks to replicate and examine in greater detail the results of a set of experiments reported in Stetson (1951). Stetson observed, based on a set of pioneering articulatory experiments, that coda consonants resyllabify as onset consonants in syllables repeated at fast speech rates. In the current experiment, speakers produced repetitions of simple CV and VC syllables in time to a metronome pacer which systematically changed in period. Data indicate that, while durational patterns for CV and VC syllables are very different at slow rates, the patterns tend to converge at fast rates. However, closer examination of fast rate tokens, reveals that differences between CV and VC tokens persist at fast rates, even though such tokens are generally heard as CV tokens. These results are discussed with respect to the nature of CV and VC organization and the effect of the rate-changing task.

Fundamental Frequency Peak Delay in Mandarin

Fundamental frequency (F₀) peak delay (henceforth peak delay) refers to the phenomenon that an F₀ peak sometimes occurs after the syllable it is associated with either lexically or prosodically. Although peak delay has been reported for various languages, the mechanism of its occurrence has so far remained unclear. In Mandarin, peak delay has been found to occur regularly in the rising (R) tone but not in the high (H) tone. The present study investigates the underlying mechanisms of peak delay by examining its relationship with tone, tonal context, and speech rate. An experiment was conducted to test the possibility that peak delay may occur also in the H tone in Mandarin if the H-carrying syllable is sufficiently shortened. Native speakers of Mandarin Chinese recorded three types of sentences each containing a H, a R, or a weakened H tone. The sentences were produced at three speech rates: normal, fast and slow. Analysis of F₀ contours and peak alignment revealed that at normal speech rate, peak delay occurred regularly in both the R and weakened H tones but only occasionally in the H tone; at slow speech rate, peak delay continued to occur regularly in the R tone but only occasionally in weakened H and rarely in the H tone; at fast speech rate, peak delay occurred not only regularly in the R and weakened H tones, but also frequently in the H tone. Results of F₀ contour alignment analysis indicate that peak delay occurs when there is a sharp F₀ rise near the end of a syllable, regardless of the cause of the rise. The finding of this study provides support for the view that, rather than due to actual misalignment between underlying pitch units and segmental units, much of the variability in the shape and alignment of F₀ contours in Mandarin is attributable to the interaction of underlying pitch targets with tonal contexts and articulatory constraints.

Post obstruent tensing in Korean: Its status and domain of application

The criteria that distinguish the phonological rules from the phonetic rules based on categoricality versus gradiency have drawn considerable attention (cf. Keating, 1990; Pierrehumbert, 1990). Korean Post Obstruent Tensing (POT) rule has been claimed, based on acoustic data, to be a phonological rule and that its domain of application is an accentual phrase (AP) (e.g., Jun, 1998). This paper questions the status of POT and its domain of application based on articulatory and acoustic data. By POT, a syllable initial lenis consonant (e.g., /t/, /s/) becomes tense (e.g., /t*/, /s*/, respectively) after an obstruent coda. It is known that lenis obstruents have a longer VOT, shorter closure durations, and shorter linguopalatal contact areas than tense obstruents. To investigate if POT is really a categorical process and if its application is definable in terms of an AP, acoustic and articulatory (i.e., EPG) data of derived and underlying tense obstruents were examined in four different prosodic positions: utterance-initial, intonational phrase-initial, AP-initial, AP-medial. Sentences containing a target sequence, /VpCV/, where C=/t/, /t*/, /s/, /s*/, were produced by two Korean speakers, at normal and fast speech rates. The results will shed light on the status of POT in the grammar of Korean.

Effect of Stimulation Rate on Cochlear Implant Recipients' Thresholds and Maximum Acceptable Loudness Levels

Clinically, speech processor programs are created using electrical thresholds and maximum acceptable loudness levels (MALs) at several different stimulation rates to determine what rate will provide cochlear implant recipients with the best speech recognition when using fast-rate speech coding strategies. This study was designed to determine the difference in thresholds and MALs (expressed in the clinical unit, Current Level [CL]) for pairs of six rates spanning those available with the Nucleus 24 device (i.e., 250 to 2,400 pps/ch) using monopolar, 25 microsec/phase stimulation. Test-retest measures of threshold and MAL for each rate were obtained from seven adult Nucleus 24 recipients on each of 11 electrodes. The difference in threshold and in MAL between pairs of rates was dependent on the absolute CL. Below approximately 190 CL, thresholds and MALs decreased with increasing rate; above 210 CL, there was little change in threshold or MAL with increasing rate. Based on these findings, an approach to estimating threshold and MAL from one rate to another is suggested, pending further research.

Effects of Speaking Rate on the Singleton/Geminate Consonant Contrast in Italian

A production and a perception experiment were conducted to investigate the effect of speaking rate on the singleton/geminate consonant contrast in Italian. Acoustic analyses were performed of labial and dental singleton and geminate consonants produced in words spoken in isolation and in a sentential context at both a slow and a fast rate of speech. Closure duration was found to discriminate between the two categories of consonants within a given speaking rate. For one speaker, at a fast speaking rate the distribution of closure duration of geminate consonants was identical to the distribution of closure duration of singleton consonants produced in isolation. However, a measure reflecting the relation between two durations, the ratio between consonant duration and preceding vowel duration, discriminated between singletons and geminates both within and across speaking rates. The perception experiment tested whether manipulation of the consonant to vowel ratio would result in perceptual shifts. Results indicated that changing the ratio did affect perception of the geminate/singleton distinction. However, these effects varied greatly across listeners. Taken together, these findings provide support for the view that there are stable acoustic properties corresponding to phonetic features in that even though one type of temporal information, closure duration, is greatly affected by changes in speaking rate, a higher-order relational measure remains constant.

Variation in the pronunciation of German ‘‘ein−’’

Pronunciation variation of German ‘‘ein−’’ is examined (unstressed indefinite article ‘‘ein,’’ ‘‘einen,’’ as well as stressed instances of ‘‘ein−,’’ i.e., the numeral or as part of a compound) based on a larger corpus of read and spontaneous speech according to segmental variation (elisions, assimilations, etc.) and acoustic features (segmental durations, extent of formant transitions, etc.). Second, the results of a combined electropalatographical/electromagnetic-articulographical study are presented. Two male subjects uttered the items ‘‘ein’’ and ‘‘einen’’ embedded in test sentences at normal, slow, and fast speech rate. Electropalatographically tongue palate contacts for the nasal segments (duration, center of gravity of contact area) were analyzed. The EMA measurements of movement from the diphthong to nasal (or from diphthong to nasal to schwa to nasal) were done with a sensor coil mounted 1 cm behind the tip of the tongue and another one mounted on a strip of elastic foil glued to the EPG palate for sensoring velar movement. Articulatory analysis revealed quite complex gestural reductions for bisyllabic ‘‘einen:’’ Even for items without schwa elision (only at a slow rate) there is no velar closing movement for the schwa.

Anticipatory Coarticulation in Aphasia: Effects of Utterance Complexity

The magnitude and extent of anticipatory coarticulation were examined in groups of fluent and nonfluent aphasic patients and normal control subjects. One- and two-syllable target utterances were elicited at slow and fast rates of speech with or without a consonant intervening between the target consonant and vowel, and with or without a preceding schwa, to manipulate utterance complexity. Acoustic analyses (F2 and centroid frequencies) revealed that both groups of aphasic patients exhibited relatively normal patterns of anticipatory coarticulation. However, small but significant differences among the groups emerged in certain conditions. Surprisingly, increased utterance complexity was not found to reduce coarticulatory effects to a greater degree in the nonfluent relative to the fluent aphasic group. Perceptual tests largely confirmed the acoustic analyses.

Perceptual adjustment to time-compressed speech: a cross-linguistic study.

Previous research has shown that, when hearers listen to artificially speeded speech, their performance improves over the course of 10-15 sentences, as if their perceptual system was "adapting" to these fast rates of speech. In this paper, we further investigate the mechanisms that are responsible for such effects. In Experiment 1, we report that, for bilingual speakers of Catalan and Spanish, exposure to compressed sentences in either language improves performance on sentences in the other language. Experiment 2 reports that Catalan/Spanish transfer of performance occurs even in monolingual speakers of Spanish who do not understand Catalan. In Experiment 3, we study another pair of languages--namely, English and French--and report no transfer of adaptation between these two languages for English-French bilinguals. Experiment 4, with monolingual English speakers, assesses transfer of adaptation from French, Dutch, and English toward English. Here we find that there is no adaptation from French and intermediate adaptation from Dutch. We discuss the locus of the adaptation to compressed speech and relate our findings to other cross-linguistic studies in speech perception.

Effects of speaking rate on voice-onset time and vowel production: Some implications for perception studies

An examination of studies investigating effects of speaking rate on speech production and speech perception reveals an apparent conflict between acoustic data from speech production and the acoustic parameters typically manipulated in speech perception experiments. This note is intended to address the apparent conflict in the literature by examining both production and perception studies in the extant literature, and by analyzing new data on the effects of speaking rate on voice-onset time (VOT) production in English. Subjects were asked to read CVC words in context at both slow and fast rates of speech, and the relationship between VOT and vowel duration across changes in speaking rate was then examined. The data for voiceless stop plus sound sequences indicate that as speaking rate slows both VOT and vowel duration increase in almost equal proportions. Importantly, there is no evidence that VOT and vowel length vary inversely such that as VOT increases, vowel length decreases. In contrast, most perception experiments examining the effects of speaking rate on VOT use stimulus parameters that do vary inversely VOT and vowel length. Thus, the perceptual the effects obtained under such conditions may not be appropriately attributable to perceptual effects of speaking rate on phonetic categorization, but rather may be due to other perceptual effects.

The effects of aging and rate on tongue shape variability and on preservation of position in glides

Slowing of neural processes due to aging may cause effects in motor speech production. In a study of /w/, Slawinski [E. B. Slawinski, J. Acoust. Soc. Am. 95, 2221–2230 (1994)] found a slower prevoicing stage, and a smaller off-glide frequency range for older speakers than younger. The latter finding suggests that older speakers centralize their articulatory gestures. Articulatory gestures may also centralize at faster speech rates. The present study compared midsagittal tongue gestures for /w/, for older versus younger subjects, matched for rate of speech. Ten female subjects (five aged 21–29, five aged 64–71) repeated: /■wVp/ and /■gwVp/ using the vowels /i,a,u/, five times each, while ultrasound video recordings were made. The hypothesis was that coarticulationwould cause different /w/ positions, (higher in /g/ context). If older subjects centralize tongue position for /w/, they might produce an even greater difference, if the high /g/ tongue position facilitated a more extreme /w/. Target frames were digitized and tongue surface edges were extracted [M. Unser and M. Stone, J. Acoust. Soc. Am. 91, 3001−3007 (1992)]. The distances between /w/ and /(g)w/ were determined using L2 norms. For two older and two younger speakers, rate effects were observed and age effects were not.