Stop Voicing Research Articles

The Development of Distinct Speaking Styles in Preschool Children

To examine when and how socially conditioned distinct speaking styles emerge in typically developing preschool children's speech. Thirty preschool children, ages 3, 4, and 5 years old, produced target monosyllabic words with monophthongal vowels in different social-functional contexts designed to elicit clear and casual speaking styles. Thirty adult listeners were used to assess whether and at what age style differences were perceptible. Children's speech was acoustically analyzed to evaluate how style-dependent differences were produced. The ratings indicated that listeners could not discern style differences in 3-year-olds' speech but could hear distinct styles in 4-year-olds' and especially in 5-year-olds' speech. The acoustic measurements were consistent with these results: Style-dependent differences in 4- and 5-year-olds' words included shorter vowel durations and lower fundamental frequency in clear compared with casual speech words. Five-year-olds' clear speech words also had more final stop releases and initial sibilants with higher spectral energy than did their casual speech words. Formant frequency measures showed no style-dependent differences in vowel production at any age nor any differences in initial stop voice onset times. Overall, the findings suggest that distinct styles develop slowly and that early style-dependent differences in children's speech are unlike those observed in adult clear and casual speech. Children may not develop adultlike styles until they have acquired expert articulatory control and the ability to highlight the internal structure of an articulatory plan for a listener.

Spectrotemporal and f0 evidence for a theory of enhancement

According to Keyser & Stevens, 2006, apart from universal features that are utilized to calculate motoric instructions, there is a second parallel and language-specific process called enhancement, where additional motoric instructions are processed for the enhancement of the saliency of features that are in danger of being obliterated. The "Standard View" on the distinction between voiced stops (VS) and voiced aspirated stops (VAS) in Hindi proposes that the breathy-murmured release following VAS is sufficient to make the contrast between the VS and VAS (Ladefoged & Maddieson, 1996). Hence, audible distinctions between VAS and VS during closure (CD/VLT) are not relevant in maintaining the contrast. Results from our studies show that CD is a relevant cue in making a distinction between aspirated and unaspirated stops. Spectral intensity measures show that speakers employ different glottal configurations to obtain the breathy/modal voicing contrast. VLT durations are inversely correlated with f0, such that longer VLT for VAS leads to further lowering of f0. This evidence suggests that f0 perturbations, differences in the durations of closure, and nature and extent of aspiration, all contribute in making the four-way stop contrast possible in Hindi, in support of a theory of enhancement.

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. ...

Stop consonant voicing and intraoral pressure contours in women and children

Previous authors have established that stop consonant voicing is more limited in young children than adults, and have ascribed this to immature vocal-tract pressure management. Physical development relevant to speech aerodynamics continues into adolescence, suggesting that consonant voicing development may also persist into the school-age years. This study explored the relationship between stop consonant voicing and intraoral pressure contours in women, 5 year olds, and 10 year olds. Productions of intervocalic /p b/ were recorded from eight speakers at each age. Measures were made of stop consonant voicing and delta, a measure designed to characterize the time course of intraoral pressure increase in stops, following Muller and Brown [Speech and Language: Advances in Basic Research and Practice, edited by N. Lass (Academic, Madison, 1980), Vol. 4, pp. 318-389]. Age effects for stop consonant voicing and delta were not statistically significant, but correlations between delta and stop voicing were less often significant and sometimes reversed in the children, providing some evidence of immature aerodynamic control. The current data, as well as those of Muller and Brown, also show that the delta measure may yield some paradoxical values, indicating that more work is needed on methods of assessing time-varying characteristics of intraoral pressure.

Perceptual processing of partially and fully assimilated words in French.

Models of speech perception attribute a different role to contextual information in the processing of assimilated speech. This study concerned perceptual processing of regressive voice assimilation in French. This phonological variation is asymmetric in that assimilation is partial for voiced stops and nearly complete for voiceless stops. Two auditory-visual cross-modal form priming experiments were used to examine perceptual compensation for assimilation in French words with voiceless versus voiced stop offsets. The results show that, for the former segments, assimilating context enhances underlying form recovery, whereas it does not for the latter. These results suggest that two sources of information -- contextual information and bottom-up information from the assimilated forms themselves -- are complementary and both come into play during the processing of fully or partially assimilated word forms.

Production of Parisian stops word‐initial stops in the vicinity of a voiceless stop

This study examines how French speakers produced stop voicing contrasts in the sentence répète CVC tout‐de‐suite. Durations (sentence, vowel before and after word‐initial stops, closure voicing, VOT) and number of produced stop closures (/t/, /C/) were collected. There was a strong positive correlation between speaker’s sentence durations and number of closure produced: Rapid speakers produced mostly one closure, whereas slow speakers generally produced two closures. One‐closure and two‐closure productions were separately analyzed. In the two‐closure productions, significant (longer voicing in the /t/ closure in anticipation of /bdg/ than /ptk/, longer closure voicing for /bdg/ than for /ptk/, longer vowel duration following /bdg/ than /ptk/) and nonsignificant voicing‐related duration differences (e.g., closure) were found. Unlike in the two‐closure productions, average closure duration was significantly longer before /ptk/ than before /bdg/, while there was no significant voicing‐conditioned effect of the word‐initial stop on the duration of the following vowel in the one‐closure productions. As in the two‐closure productions, average closure voicing duration remained significantly longer before /bdg/ than before /ptk/. Findings suggest that closure voicing remains the most salient cue to the voicing distinction irrespective of contextual and speaking rate variations.

The Saramaccan implosives

This paper takes as its starting point the recently discovered fact that Saramaccan contrasts two types of voiced labial and coronal stop, plain and implosive. The plain labials appear to be modern in origin, something which cannot be said about their coronal counterparts. So we reconstruct an earlier situation in Saramaccan in which only one type of labial voiced stop, the implosive, was present, but both types of coronal. The Gbe languages also have one voiced labial stop, and two coronals, although none of these are implosive. It can be demonstrated, however, that a near-regular correspondence exists between the three putative Saramaccan voiced stops and the three Gbe stops, and conclude that this is an additional piece of evidence for the role of Fon/Gbe as a substrate language for Saramaccan. We further discuss the implications this correspondence has for views on the nature of the 17th century Fon consonant system.

F2 Locus Equations: Phonetic Descriptors of Coarticulation in 17- to 22-Month-Old Children

The general purpose of this research was to describe coarticulation across voiced stop consonant place of articulation in 10 children younger than 2 years of age. A total of 1,182 voiced stop CV productions was analyzed using the locus equation metric, which yielded 3 regression lines that described the relation of F2 onset and F2 vowel for /bV/, /dV/, and /gV/ productions. The results revealed significant differential effects for slope and y-intercept as a function of stop consonant place of articulation. The ordering of the mean slope values for stop consonant place of articulation was /g/>/b/ and /d/, indicating that /g/ was produced with significantly greater coarticulation than /b/ or /d/. However, the unique vowel allophonic pattern of [g] coarticulation reported in the literature for English-speaking adults was generally not learned by these young children. Group and individual coarticulation trends are described in relation to developmental theories of sound acquisition. Results suggest that early coarticulation patterns are phoneme specific.

Cross-linguistic tendencies and durational contrasts in geminate consonants: an examination of Guinaang Bontok geminates

In Guinaang Bontok, there is a phonological contrast between singletons and geminates in all consonants (/p t k ? b d g m n ŋ l s w j/) (Reid 1963, 1973; Thurgood 1997). All phonological geminates except for the oral voiced stop geminates are phonetically long consonants (Reid 1963), allowing a phonological distinction which is primarily based on phonetic duration for nasals, fricatives, liquids, glides and voiceless stops. In a cross-linguistic examination of geminates (Thurgood 1993), there were more languages listed as examples for having stop and nasal geminates than for glide geminates, and it was suggested that alveolar was the cross-linguistically preferred place of articulation for geminate consonants. In this study, it was hypothesized that the cross-linguistically less common length contrasts, such as the length contrasts in glides, were phonetically less clear than the more common ones, such as contrasts between short and long stop and nasal consonants. Similarly, it was hypothesized that contrasts in the cross-linguistically common place of articulation (i.e. alveolar) is phonetically clearer than less common contrasts (e.g. velar). In order to test these hypotheses, duration measurements were conducted on single and geminate consonants in Guinaang Bontok. The average durational contrast between short and long glides was smaller than the contrast in stop and nasal consonants. The hypothesis was therefore partially supported.

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.

Voice onset time of bilingual English and French-speaking Canadians

There is evidence of voice onset drift when bilinguals are submerged in cultures that are dominated by their second language (L2). Sancier and Fowler [Gestural drift in a bilingual speaker of Brazilian Portuguese and English,‘‘ J. Phonet. 4, 421-436 (1997)] found that voiceless stop voice onset times (VOTs) of a bilingual speaker of Brazilian Portuguese and English were longer after months spent in the US than after time spent in the speaker’s first language (L1) context. Flege [’’The production of ‘‘new’’ and ‘‘similar’’ phones in a foreign language: Evidence for the effect of equivalence classification,‘‘ J. Phonet. 15, 47–65 (1987)] studied French L1 English L2 bilinguals and English L1 French L2 bilinguals who had spent about 12 years living in the L2 dominant culture. The French L1 English L2 bilinguals VOTs were longer than the VOTs of French monolinguals. The English L1 French L2 bilinguals VOTs were shorter than the VOTs of English monolinguals. In the present study the nature of the experience underlying VOT drift was investigated. Specifically, the aim of the current study was to see whether exposure to another language with different VOTs affects VOT production in the first (or only) language or if VOT production drift is dependent on speaking the non-native language. Productions from English and French monolinguals and from English-French bilinguals were compared across varying linguistic contexts and order of acquisition.

A voice for the voiceless: Production and perception of assimilated stops in French

Previous studies, mainly conducted on English running speech, have reported that (place) assimilation between words is usually incomplete, and have suggested that the perceptual processing of word forms altered by that assimilation depends on the extent to which phonemes at word boundary have undergone assimilation. The present research provides an acoustic–phonetic description of regressive voice assimilation in French and proposes an objective measure of “voicing degree” for stops in word-final position. This measure is the relative duration of voicing within the stop closure. It is shown to closely correlate with perceptual judgments of voicedness. Across two experiments, we show that voice assimilation in French is graded and asymmetrical in that voiceless stops assimilate to a larger extent than voiced stops do. It also appears that assimilation is slightly modulated by lexical factors such as potential ambiguity and phonological neighborhood. If a word belongs to a minimal pair for final stop voicing (e.g., rate /rat/ ‘spleen’ minimally contrasts with rade /rad/ ‘harbor’), assimilation strength tends to be weaker. The same trend applies to a word challenged by ‘dangerous’ phonological neighbors that only differ from it by their word-final consonant.

Age-related differences in weighting and masking of two cues to word-final stop voicing in noise

Because laboratory studies are conducted in optimal listening conditions, often with highly stylized stimuli that attenuate or eliminate some naturally occurring cues, results may have constrained applicability to the "real world." Such studies show that English-speaking adults weight vocalic duration greatly and formant offsets slightly in voicing decisions for word-final obstruents. Using more natural stimuli, Nittrouer [J. Acoust. Soc. Am. 115, 1777-1790 (2004)] found different results, raising questions about what would happen if experimental conditions were even more like the real world. In this study noise was used to simulate the real world. Edited natural words with voiced and voiceless final stops were presented in quiet and noise to adults and children (4 to 8 years) for labeling. Hypotheses tested were (1) Adults (and perhaps older children) would weight vocalic duration more in noise than in quiet; (2) Previously reported age-related differences in cue weighting might not be found in this real-world simulation; and (3) Children would experience greater masking than adults. Results showed: (1) no increase for any age listeners in the weighting of vocalic duration in noise; (2) age-related differences in the weighting of cues in both quiet and noise; and (3) masking effects for all listeners, but more so for children than adults.

Hemispheric lateralization of voice onset time (VOT) comparison between depth and scalp EEG recordings

Auditory-evoked potential (AEP)s elicited to French-language voiced stop consonant (/ba/) and voiceless stop consonant (/pa/) were studied in non-language-impaired epileptic patients and non-epileptic volunteers. First, depth AEPs recorded from the primary auditory cortex during pre-surgical exploration and scalp AEPs recordings using high resolution EEG (HR EEG-64 channels scalp EEG) were compared in the same patients. Both methods indicated that the processing of voiced and voiceless consonants was based on a temporal auditory coding. /Ba/ elicited a first complex (N1) at the onset of voicing and a second component [release component (RC)] time-locked to release. This processing took place specifically in the left primary auditory cortex. Source modeling of the RC showed that a left-greater-than-right amplitude of source probes (SP) both in epileptic patients with left-hemispheric language dominance [established by means of invasive tests (WADA test) and/or clinical data] and right-handed non-epileptic subjects. Our data suggest that the processing of VOT is related to hemispheric dominance for language and that scalp-recorded AEPs may represent an effective, non-invasive method to establish hemispheric dominance for language in clinical settings. This procedure could complement existing methods and could help to detect the dissociation between receptive and expressive language sometimes observed in patients with epilepsy.

A new method of extracting the filter characteristics of the nasal cavity using homorganic nasal-stop sequences

This study attempts to derive the filter characteristics of the nasal cavity of individual speakers. Since the only difference between a nasal and a homorganic voiced stop, such as [mb] and [nd], is whether the passage to the nasal cavity is open or not, the subtraction of the LPC spectrum of the voiced stop from that of the preceding nasal leads to the filter characteristics of the nasal cavity of an individual speaker regardless of place of articulation. The results showed that the spectral differences between samples of 20 ms taken from the steady states of the nasal and the following voiced stop were close to constant regardless of place of articulation, representing characteristic poles and zeroes, and that the spectral differences varied with speakers. This study is significant in that it provides a new method of extracting the filter characteristics of the nasal cavity, and that the spectral difference between a nasal and a homorganic voiced stop can be used as a parameter of the filter characteristics of the nasal cavity of individual speakers.

The emergence of mature gestural patterns in the production of voiceless and voiced word-final stops

The organization of gestures was examined in children's and adults' samples of consonant-vowel-stop words differing in stop voicing. Children (5 and 7 years old) and adults produced words from five voiceless/voiced pairs, five times each in isolation and in sentences. Acoustic measurements were made of vocalic duration, and of the first and second formants at syllable center and voicing offset. The predicted acoustic correlates of syllable-final voicing were observed across speakers: vocalic segments were shorter and first formants were higher in words with voiceless, rather than voiced, final stops. In addition, the second formant was found to differ depending on the voicing of the final stop for all speakers. It was concluded that by 5 years of age children produce words ending in stops with the same overall gestural organization as adults. However, some age-related differences were observed for jaw gestures, and variability for all measures was greater for children than for adults. These results suggest that children are still refining their organization of articulatory gestures past the age of 7 years. Finally, context effects (isolation or sentence) showed that the acoustic correlates of syllable-final voicing are attenuated when words are produced in sentences, rather than in isolation.

Underlying Voicing in Majorcan Catalan Word-Final Stop-Liquid Clusters

This study investigates the extent to which phonetic voicing is maintained inword-final clusters composed of an underlying voiced stop followed by nonsyllabic/l/ or /r/ in Majorcan Catalan. Electropalatographic and acoustic data forfive speakers of this Catalan dialect reveal that, in agreement with the non-syllabicstatus of the liquid, voicing for /l/ is only available if occurring during the precedingstop. The rhotic is always phonetically voiceless. Speakers differ regarding theextent to which they keep the underlying stop voicing distinction and the productionstrategies they use for that purpose. This distinction is highly robust and distributedover the entire syllable in nasal-stop-/l/ clusters for some speakers, butmuch less clear or absent for those speakers who devoice /l/ as a general rule.Underlying stop voicing is cued primarily by stop closure duration and vocal foldvibration, or else by closure duration rather than by voicing. It may be concludedthat the word-final devoicing process operating in Catalan does not apply toMajorcan Catalan tautosyllabic stop clusters with a liquid, and that phonetic voicingmay affect just the stop or both the stop and the liquid. The implications ofthese findings for sound change are discussed.

Vowel duration as a cue to postvocalic stop voicing in aphasia and apraxia of speech

Background: In American English, vowel duration is, on average, longer preceding postvocalic voiced stops than preceding postvocalic voiceless stops. Preliminary investigations have reported a preservation of this acoustic contrast for speakers with aphasia and apraxia of speech (AOS) on the basis of mean data. However, clinical interpretation of the available research is difficult due to lack of attention to the range of performance among and within speakers from both normal and disordered populations. Concurrent perceptual analysis is warranted to evaluate functional implications of acoustic variations, but standard approaches using a single listener and presentation may not be sufficiently sensitive to reveal subtle variations.Aims: (1) To determine whether aphasic and apraxic speakers produce a normal vowel duration differentiation between voiced and voiceless postvocalic stops. (2) To explore whether the produced vowel duration variations are associated with predicted perceptual effects.Methods & Procedures: Eight speakers with coexisting aphasia and AOS, eight with aphasia and no AOS, and eight normal control speakers produced 24 repetitions of the words “had” and “hat” in a short carrier phrase. For each utterance, the duration of the vowel was measured. Perceptual testing was conducted using three normal listeners and a forced‐choice perceptual identification paradigm.Outcomes & Results: As expected, all normal speakers, and most aphasic and apraxic speakers, displayed a mean vowel duration distinction between the voicing cognates. The magnitude of the distinction did not differ across groups. Instead, there was substantial inter‐speaker variability in the magnitude of duration contrast in all three groups. Some aphasic speakers with and without AOS did not distinguish in vowel duration between voicing cognates, and others displayed bimodal, but overlapping, distributions for /d/ and /t/. Results of the perceptual identification experiment indicated that there was good, but not perfect, agreement between variations in vowel duration and voicing perception and that several utterances produced by aphasic and apraxic speakers were perceptually ambiguous.Conclusions: (1) Although the mean duration for vowels preceding voiced and voiceless stops may be indistinguishable from normal, several abnormal acoustic patterns are found among individual aphasic speakers both with and without AOS. (2) The magnitude of acoustic distinction can vary considerably across normal speakers and this variation must be considered when evaluating disordered speech. (3) Perceptual identification testing facilitates the interpretation of acoustic data, particularly when the two levels of analysis are matched on an utterance‐by‐utterance basis. (4) Perceptual ambiguity can be demonstrated in disordered speech through perceptual identification testing.

Developmental changes in the perception of syllable-final stop voicing are not explained by age-related differences in auditory sensitivity

Two cues to voicing decisions for syllable-final stops are vocalic duration and formant transitions, especially F1, at syllable offset. Developmental studies show that children weight vocalic duration less and formant transitions more than adults. This study tested the hypothesis that age-related differences in auditory sensitivity can explain these developmental changes by measuring adults’ and children’s sensitivities to changes in the duration of nonspeech, complex tones and analogous speech stimuli. The durations of three-tone sinusoidal stimuli and natural cob and cop were varied. Duration difference limens (DLs) were similar for listeners across ages, and similar for nonspeech and speech. Also, the extent of frequency fall was varied in three-tone sinusoidal stimuli for the first tone (T1) only or for all three tones, as well as for F1 only in synthetic buck/bug. DLs for frequency extent were similar for listeners across ages for nonspeech stimuli when all three tones fell, but children had larger DLs than adults when only T1 or F1 fell, a finding contrary to labeling results showing that children weight this very property more than adults. Overall the evidence contradicted the hypothesis that age-related differences in auditory sensitivity can explain developmental changes in the perception of syllable-final stop voicing.

The role of temporal and dynamic signal components in the perception of syllable-final stop voicing by children and adults

Adults whose native languages permit syllable-final obstruents, and show a vocalic length distinction based on the voicing of those obstruents, consistently weight vocalic duration strongly in their perceptual decisions about the voicing of final stops, at least in laboratory studies using synthetic speech. Children, on the other hand, generally disregard such signal properties in their speech perception, favoring formant transitions instead. These age-related differences led to the prediction that children learning English as a native language would weight vocalic duration less than adults, but weight syllable-final transitions more in decisions of final-consonant voicing. This study tested that prediction. In the first experiment, adults and children (eight and six years olds) labeled synthetic and natural CVC words with voiced or voiceless stops in final C position. Predictions were strictly supported for synthetic stimuli only. With natural stimuli it appeared that adults and children alike weighted syllable-offset transitions strongly in their voicing decisions. The predicted age-related difference in the weighting of vocalic duration was seen for these natural stimuli almost exclusively when syllable-final transitions signaled a voiced final stop. A second experiment with adults and children (seven and five years old) replicated these results for natural stimuli with four new sets of natural stimuli. It was concluded that acoustic properties other than vocalic duration might play more important roles in voicing decisions for final stops than commonly asserted, sometimes even taking precedence over vocalic duration.