Production Of Stop Consonants Research Articles

Velar–vowel coarticulation in a virtual target model of stop production

Velar–vowel coarticulation in English, resulting in so-called velar fronting in front vowel contexts, was studied using ultrasound imaging of the tongue during /k/ onsets of monosyllabic words with no coda or a labial coda. Ten native English speakers were recorded and analyzed. A variety of coarticulation patterns that often appear to contain small differences in typical closure location for similar vowels was found. An account of the coarticulation pattern is provided using a virtual target model of stop consonant production where there are two /k/ allophones in English, one for front vowels and one for non-front vowels. Small differences in closure location along the palate between productions within each context are the result of the trajectory of movement of the tongue from the vowel to vowel through the virtual target beyond the limit of the palate. The overall pattern is thus seen as a combination of a large planned allophonic difference between consonant closure targets and smaller phonetic differences for each particular vowel quality that are the result of coarticulation.

Acoustic modeling of the perception of place information in incomplete stops

Previous research on stop consonant production found that less than 60% of the stops sampled from a connected speech corpus contained a clearly defined hold duration followed by a plosive release [Crystal & House, JASA 1988]. How listeners perceive the remaining portion of incomplete stop consonants is not well understood. The purpose of the current study was to investigate whether relative formant deflection patterns, a potential model of acoustic invariance proposed by Story and Bunton (2010), is capable of predicting listeners’ perceptions of acoustically continuous, voiced stop consonants lacking a canonical hold duration. Listeners were randomly presented a total of 60 voiced stop-consonant VCV stimuli, each 100 ms in duration, synthesized using a computational model of speech production. Stimuli were created using a continuum of 20 equal step constrictions along the length of the vocal tract in three vowel-to-vowel contexts [see Story & Bunton, JSLHR 2010]. Participants listened to the stimuli and performed a forced choice test (i.e., /b-d-g/). The phonetic boundaries predicted by the relative formant deflection patterns and phonetic boundaries obtained by the forced choice test were compared to determine the ability of the acoustic model to predict participants’ perceptions. The acoustic and perceptual results are reported. [Work supported by NIH R01-DC011275.]

Stop consonant production of French immersion students in Western Canada: A study of voice onset time

Objectives/research questions: The present study investigates the development of French stop consonants among English-speaking children who are enrolled in an early French immersion program in Lethbridge, Alberta, Canada. Our goal is to observe the stop consonant production pattern, and to determine whether interactions between the two language systems occur, while examining student progression with increasing experience. Methodology: Fifty-six students in grades 1, 3, and 5 participated in a speech production task administered in both English and French. For each language, they were asked to repeat a total of 54 words beginning with one of the six stop consonants, /p/, /t/, /k/, /b/, /d/, and /g/. In addition, 45 age-matched monolingual English-speaking children were tested to serve as a control group. Data and analysis: Voice onset time (VOT) was the acoustic measure analyzed for each language and for children of each grade. An analysis of variance was conducted for language- and experience-related effects. Conclusions: For the French voiceless stops, French immersion students display non-native-like VOT values in the intermediate range between monolingual English voiced and voiceless stops. Their English voiceless stops exhibit higher VOT values than the monolinguals’ and are separate from those of their French. For voiced stops, their English and French are indistinguishable, located within the range of voiced stops for monolingual English speakers. Originality: Previous research on French–English bilingualism has generally been limited to adults. Furthermore, examination of French immersion students has rarely focused on their phonetic development, and acoustic analysis of this population is virtually non-existent. Implications: Our results highlight the importance of input, as well as social, and educational context in second language learning.

Articulatory Movement during Production of Lingua-Alveolar Stop Consonants in a Case of Congenital Aglossia

Background: This manuscript, the sixth in a series, discusses an investigation into production of lingua-alveolar stop consonants /tEŒ/ and /dEŒ/ by a person with congenital aglossia (PwCA), and the specific anatomical and physiological properties and kinematics involved. Methods: In this study, a modified barium swallow study was performed to analyze the PwCA's oral and pharyngeal tract, in addition to a video speech recording made during a series of imitative tasks isolating specific English phonemes (/tEŒ/ and /dEŒ/). Researchers evaluated the PwCA's vertical and horizontal range of motion (ROM) of the mobile articulators (i.e., mylohyoid, tongue base, lower incisors, hyoid) during /tEŒ/ and /dEŒ/ production, and whether these phonemes could be predicted by their ROM and graphic representation. Additionally, researchers analyzed horizontal and vertical movement to identify correlational patterns between dependent (DVs) (i.e., lower incisors, hyoid) and independent variables (IVs) (i.e., lower lip, mylohyoid, tongue base) during production of /tEŒ/ and /dEŒ/, and the relationships of variables during movement and predictive variable correlation values. Results: Results revealed that /tEŒ/ and /dEŒ/ were distinct in specific horizontal and vertical distances of ROM and corresponding horizontal and vertical relationships. Additionally, although the horizontal correlation patterns for IVs and DVs were similar in statistical significance, this was not found between hyoid and mylohyoid. Significant positive correlations were found for /dEŒ/ (r=0.581, p 0.05). In vertical axis for /dEŒ/, both DVs were significantly correlated with all IVs except mylohyoid with lower incisor (r=0.233, p>0.05). For /tEŒ/, only three correlations were significant. Hyoid was significantly correlated with tongue base (r=0.648, p<0.05), and lower incisors were significantly correlated with mylohyoid (r=0.420, p<0.05), and lower lip (r=0.923, p<0.05). Finally, multiple distinct ROM differences and significant correlations were observed that made kinematics of /dEŒ/ distinct and identifiable from /tEŒ/.

Individualized current-shaping reduces DBS-induced dysarthria in patients with essential tremor

Objective:To investigate in patients with essential tremor (ET) treated with thalamic/subthalamic deep brain stimulation (DBS) whether stimulation-induced dysarthria (SID) can be diminished by individualized current-shaping with interleaving stimulation (cs-ILS) while maintaining tremor suppression (TS).Methods:Of 26 patients screened, 10 reported SID and were invited for testing. TS was assessed by the Tremor Rating Scale and kinematic analysis of postural and action tremor. SID was assessed by phonetic and logopedic means. Additionally, patients rated their dysarthria on a visual analog scale.Results:In 6 of the 10 patients with ET, DBS-ON (relative to DBS-OFF) led to SID while tremor was successfully reduced. When comparing individualized cs-ILS with a non–current-shaped interleaving stimulation (ILS) in these patients, there was no difference in TS while 4 of the 6 patients showed subjective improvement of speech during cs-ILS. Phonetic analysis (ILS vs cs-ILS) revealed that during cs-ILS there was a reduction of voicing during the production of voiceless stop consonants and also a trend toward an improvement in oral diadochokinetic rate, reflecting less dysarthria. Logopedic rating showed a trend toward deterioration in the diadochokinesis task when comparing ON with OFF but no difference between ILS and cs-ILS.Conclusion:This is a proof-of-principle evaluation of current-shaping in patients with ET treated with thalamic/subthalamic DBS and experiencing SID. Data suggest a benefit on SID from individual shaping of current spread while TS is preserved.Classification of evidence:This study provides Class IV evidence that in patients with ET treated with DBS with SID, individualized cs-ILS reduces dysarthria while maintaining tremor control.

Segmental and Prosodic Effects on Intervocalic Voiced Stop Reduction in Connected Speech

De scriptions of lenition have often assumed that connected speech reductions are the phonetic precursors of phonological lenition processes. In this article, production of intervocalic voiced stops during reading in American English is examined to determine whether connected speech reduction processes mirror the stages of lenition that have been posited in the phonological literature. The first result shows that American English speakers never lenite to fricatives or debuccalize to [h] or glottal stop, but rather produce approximants whenever reduction occurs. Second, stress plays an essential role: 51% of stops are produced as approximants when stress is on the preceding syllable (e.g. ‘yoga'), but only 7% of stops weaken when stress is on the following syllable (e.g. ‘lagoon'). Approximant productions are longer and higher in intensity than stop productions when stress precedes the target consonant, but when stress follows the target consonant, the stop cues are enhanced. These acoustic findings suggest that English speakers prioritize the realization of acoustic cues to stress, including the robust production of stop consonants, over pressures to reduce or weaken consonants in intervocalic position.

Foreign accent production and perception: An acoustic analysis of non-native Japanese

What are the characteristics of non-native speech and what contributes to the perception of foreign accent by native speakers? In this study, two experiments are conducted to characterize the acoustic features of non-native Japanese production and to examine how these non-native features influence native Japanese perception of foreign accent. In the production experiment, stop consonants and vowel formants were compared between native Japanese speakers and English speakers with 2 and 4 yr of Japanese instruction. The second experiment examines native listener judgments of foreign accent using a visual analog scale. Preliminary analysis reveals that in both stop consonant and vowel production, learners vary considerably from native speakers, specifically in the production of /k/ and /t/ voice onset time, F1 of /e/, and F2 of /u/ and /i/. These features are correlated with judgment ratings by native Japanese listeners. The findings reveal that even after significant experience in the L2 classroom, speakers still struggle to achieve native-like production of various segments, offering insight into specific problem areas which native English speakers might encounter when learning Japanese pronunciation.

Stop consonant productions of Korean–English bilingual children

The purpose of this study was to conduct an acoustic examination of the obstruent stops produced by Korean–English bilingual children in connection with the question of whether bilinguals establish distinct categories of speech sounds across languages. Stop productions were obtained from ninety children in two age ranges, five and ten years: thirty Korean–English bilinguals, thirty monolingual Koreans and thirty monolingual English speakers. Voice-Onset-Time (VOT) lag at word-initial stop and fundamental frequency (f0) in the following vowel (hereafter vowel-onset f0) were measured. The bilingual children showed different patterns of VOT in comparison to both English and Korean monolinguals, with longer VOT in their production of Korean stop consonants and shorter VOT for English. Moreover, the ten-year-old bilinguals distinguished all stop categories using both VOT and vowel-onset f0,whereas the five-year-olds tended to make stop distinctions based on VOT but not vowel-onset f0. The results of this study suggest that bilingual children at around five years of age do not yet have fully separate stop systems, and that the systems continue to evolve during the developmental period.

Acoustic and spectral patterns in young children’s stop consonant productions

The aim of this study was to examine the acoustic and spectral patterns of stop articulation in the speech of pre-pubescent children. A set of voiceless stop consonants, /ptk/, produced by a group of adults and typically developing children 3-5 years of age were examined in terms of multiple acoustic and spectral parameters. Findings indicated that, with the exception of spectral kurtosis, the acoustic and spectral characteristics of the stop productions varied significantly as a function of place of articulation and vowel context. Sex-specific differences in spectral slope, mean, and skewness were found for the 5-year-old and adult speakers. Such differences in adult speakers can be explained in part by variation in vocal tract size across the sex of the speaker; however, vocal tract dimorphism is typically not present in pre-pubescent children. Thus, the findings of this study provide some support that sex-specific differences in the speech patterns of young children may be associated with learned or behavioral factors, such as patterns of obstruent articulation that depend in part on a culturally determined male-female archetype.

Measuring sensitivity to short‐term deviations in acoustic cue correlation.

Listeners are sensitive to correlations among the multiple probabilistic acoustic cues that define speech categories. In English stop consonant productions, for example, fundamental frequency (f0) is strongly correlated with voicing. Reflecting this regularity, perception of syllables varying in voice onset time is shifted with changes in f0. Such sensitivity to the long‐term regularities of a language must be balanced with enough flexibility that speech perception is able to accommodate deviations from these regularities, such as those that may arise variations from idiolect, dialect, or accented speech. The present experiments manipulate short‐term acoustic cue correlations experienced in online perception to investigate the interplay between sensitivity to long‐term and short‐term acoustic cue correlation. Using overt categorization and eyetracking, the present results indicate that speech categorization is influenced by local shifts in acoustic cue correlations that deviate from long‐term regularities of English. These experiments further examine the time course of this short‐term learning and the degree to which it generalizes. The data suggest that listeners continually monitor speech input for regularity and tune online speech perception in relation to these regularities.

Estimation of Place of Articulation During Stop Closures of Vowel–Consonant–Vowel Utterances

Production of vowel-oral stop consonant-vowel utterances involves movement of articulators from the articulatory position of the initial vowel towards that of the oral stop closure, and then to that of the final vowel. As the closure segments have zero or low signal energy, linear predictive coding (LPC)-based estimation of vocal tract shape fails during stop closure. This paper reports a technique for estimation of place of articulation during stop closures by performing bivariate polynomial modeling on vocal tract area values during transition segments preceding and following the closure. The technique with second-degree polynomial modeling was found to be suitable for estimating the place of maximum constriction during stop closure segments of vowel-consonant-vowel utterances with bilabial, alveolar, and velar stops. The estimated places compared well with the actual constriction locations observed from the articulatory data. The technique may be useful for improving effectiveness of speech-training aids for production of stop consonants by providing visual feedback of the estimated place of articulation.

Computer simulations of intraoral pressure patterns during voiced stop consonant production

Several past studies have used laryngeal and/or upper vocal tract models to explore aerodynamic control during production of obstruent consonants, yet many aspects of such control remain unclear. Of particular interest in this work is how varying laryngeal and vocal tract dimensions such as occur among men, women, and children influence phonatory behavior and the time course of intraoral pressure (Pio) increase during voiced stop consonant production. To maintain phonation during a voiced stop closure, Pio must remain below the subglottal pressure. Physiological and modeling studies indicate that adult speakers actively increase supraglottal volumes during voiced stops, which slows the rate of Pio increase. Speakers with smaller vocal tracts may either be less successful in slowing the rate of Pio buildup, or else may perform more extreme volumetric changes to achieve similar end results. The current study uses data recently collected on voicing and Pio during stop production in men, women, and children. ...

A Comparisons Study of Bilabial Stop-Consonant Perception and Production by Hearing-impaired Children

A Comparisons Study of Bilabial Stop-Consonant Perception and Production by Hearing-impaired Children

Voice onset time production in speakers with Alzheimer's disease

In the present study, voice onset time (VOT) measurements were compared between a group of individuals with moderate Alzheimer's disease (AD) and a group of healthy age‐ and gender‐matched peers. Participants read a list of consonant‐vowel‐consonant (CVC) words, which included the six stop consonants. The VOT measurements were made from oscillographic displays obtained from the Brown Laboratory Interactive Speech System (BLISS) implemented on an IBM‐compatible computer. VOT measures for the participants' six stop consonant productions were subjected to statistical analysis. The results indicated that VOT values in speakers with Alzheimer's disease were not statistically different from those for the normal control speakers.

Estimation of Transpalatal Nasalance during Production of Voiced Stop Consonants by Noncleft Speakers Using an Oral-Nasal Mask

Our objective was to estimate nasalance due to transpalatal transfer of acoustic energy during production of voiced stop consonants by noncleft speakers. We also determined the relationship between the transpalatal nasalance and fundamental frequency (F0) of the speakers. Participants were 8 men and 10 women (mean age = 21.9 years, SD = 4.0) without cleft palate who produced voiced stop (/b d g/) and nasal (/m n eta/) consonants in syllables embedded in a carrier phrase. Participants also read the Zoo Passage. A divided OroNasal Nasality System mask was used to simultaneously obtain acoustic nasalance and airflow during production of the consonants. Both F0-derived and first formant (F1)-derived nasalance were computed. F0-derived and F1-derived peak nasalance across all speakers ranged from a low of 20% to a high of 80% during production of stop consonants. An estimate of error from the combined sources of transoral transfer of energy (5%) and acoustic crossover between microphones (15%) was no greater than 20%. Analysis of variance revealed no significant effects of the sex of the speakers for either F0-derived or F1-derived nasalance of stops. There was a significant effect of the place of stop production for F0-derived nasalance (p;th< .05). Nonsignificant but positive correlations were found between the F0 of the speakers and F0-derived (r = .25) and F1-derived (r = .45) nasalance. Transpalatal transfer of oral acoustic energy accounts for most nasalance obtained during production of voiced stop consonants by noncleft speakers. F1-derived nasalance appears to better reflect transpalatal effects. Clinical implications are discussed.

Air pressure responses to sudden vocal tract pressure bleeds during production of stop consonants: new evidence of aeromechanical regulation.

Two studies were conducted to evaluate short-latency vocal tract air pressure responses to sudden pressure bleeds during production of voiceless bilabial stop consonants. It was hypothesized that the occurrence of respiratory reflexes would be indicated by distinct patterns of responses as a function of bleed magnitude. In Study 1, 19 adults produced syllable trains of "puh" using a mouthpiece coupled to a computer-controlled perturbator. The device randomly created bleed apertures that ranged from 0 to 40 mm2 during production of the 2nd or 4th syllable of an utterance. Although peak oral air pressure dropped in a linear manner across bleed apertures, it averaged 2 to 3 cm H2O at the largest bleed. While slope of oral pressure also decreased in a linear trend, duration of the oral pressure pulse remained relatively constant. The patterns suggest that respiratory reflexes, if present, have little effect on oral air pressure levels. In Study 2, both oral and subglottal air pressure responses were monitored in 2 adults while bleed apertures of 20 and 40 mm2 were randomly created. For 1 participant, peak oral air pressure dropped across bleed apertures, as in Study 1. Subglottal air pressure and slope, however, remained relatively stable. These patterns provide some support for the occurrence of respiratory reflexes to regulate subglottal air pressure. Overall, the studies indicate that the inherent physiologic processes of the respiratory system, which may involve reflexes, and passive aeromechanical resistance of the upper airway are capable of developing oral air pressure in the face of substantial pressure bleeds. Implications for understanding speech production and the characteristics of individuals with velopharyngeal dysfunction are discussed.

Air Pressure Responses to Sudden Vocal Tract Pressure Bleeds During Production of Stop Consonants: New Evidence of Aeromechanical Regulation

Air Pressure Responses to Sudden Vocal Tract Pressure Bleeds During Production of Stop Consonants: New Evidence of Aeromechanical Regulation

Influences of tongue biomechanics on speech movements during the production of velar stop consonants: a modeling study.

This study explores the following hypothesis: forward looping movements of the tongue that are observed in VCV sequences are due partly to the anatomical arrangement of the tongue muscles, how they are used to produce a velar closure, and how the tongue interacts with the palate during consonantal closure. The study uses an anatomically based two-dimensional biomechanical tongue model. Tissue elastic properties are accounted for in finite-element modeling, and movement is controlled by constant-rate control parameter shifts. Tongue raising and lowering movements are produced by the model mainly with the combined actions of the genioglossus, styloglossus, and hyoglossus. Simulations of V1CV2 movements were made, where C is a velar consonant and V is [a], [i], or [u]. Both vowels and consonants are specified in terms of targets, but for the consonant the target is virtual, and cannot be reached because it is beyond the surface of the palate. If V1 is the vowel [a] or [u], the resulting trajectory describes a movement that begins to loop forward before consonant closure and continues to slide along the palate during the closure. This pattern is very stable when moderate changes are made to the specification of the target consonant location and agrees with data published in the literature. If V1 is the vowel [i], looping patterns are also observed, but their orientation was quite sensitive to small changes in the location of the consonant target. These findings also agree with patterns of variability observed in measurements from human speakers, but they contradict data published by Houde [Ph.D. dissertation (1967)]. These observations support the idea that the biomechanical properties of the tongue could be the main factor responsible for the forward loops when V1 is a back vowel, regardless of whether V2 is a back vowel or a front vowel. In the [i] context it seems that additional factors have to be taken into consideration in order to explain the observations made on some speakers.

Efficacy of speech intervention using electropalatography with a cochlear implant user

Electropalatography (EPG) has become relatively well established as a safe and convenient technique for use in the assessment, diagnosis and treatment of children and adults with articulation disorders. EPG's wide applicability is reflected in the range of different cases that has been researched in recent years. Some research has been carried out using EPG therapy for deaf individuals who use hearing aids, however there are no similar studies for cochlear implant users. The purpose of this single case study is to explore the technique of EPG as a therapeutic intervention to treat voiceless velar stop consonant sound production in a deaf child cochlear implant user. EPG therapy was offered as a last resort when traditional therapy failed to achieve specific changes. During therapy, a list of familiar words was practised, using the visual feedback provided by EPG. The client's articulation was assessed using objective (EPG printouts) and subjective (listener ratings) measures at four assessment points. Changes were found to be statistically significant. Generalization of the newly‐acquired skills to untaught words containing voiceless velars was also observed. The results are discussed in the broader context of implications of this type of therapy with deaf clients.

Control of closure duration in labial stop consonants

This paper examines lip and jaw kinematics in the production of labial stop consonants where the duration of the oral closure is varied for linguistic purposes. The subjects were speakers of Japanese and Swedish, two languages that have a contrast between short and long consonants. Lip and jaw movements were recorded using a magnetometer system. Based on earlier work showing that the lips are moving at a high velocity at the oral closure, it was hypothesized that speakers could control closure duration by varying the position of a virtual target for the lower lip. According to this hypothesis, the peak vertical position of the lower lip during the oral closure should be higher for the long than for the short stops. This would result in the lips staying in contact for a longer period. Results from five subjects suggest that this is the case for those who produce nonoverlapping distributions of closure duration for the two categories. However, the peak velocity of the lower lip raising movement did not always differ between the two categories, suggesting that differences in muscle activation duration rather than virtual target position is another potential control variable. [Work supported by the NIH.]