Fricative Production Research Articles

Source characteristics of voiceless dorsal fricatives

Aerodynamic and acoustic data on voiceless dorsal fricatives [x/χ] in Arabic, Persian, and Spanish were recorded to measure the extent to which such productions involve trilling of the uvula, thus exhibiting a sound source which, contrary to assumptions for voiceless fricatives, is mixed rather than aperiodic. Oscillation in airflow indicative of uvular vibration was present more often than not in Arabic (63%) and Persian (75%), while Spanish dorsal fricatives were more commonly produced with unimodal flow indicative of an aperiodic source. When present, uvular vibration frequencies averaged 68 Hz in Arabic and 67 Hz in Persian. Rates of uvular vibration were highly variable, however, and ranged between 40 and 116 Hz, with oscillatory periods averaging 4-5 cycles in duration, with a range of 1-12. The effect of these source characteristics on dorsal fricative acoustics was to significantly skew the spectral shape parameters (M1-M4) commonly used to characterize properties of the anterior filter; however, spectral peak frequency was found to be stable to changes in source characteristics, suggesting the occurrence of trilled tokens is not due to velar-uvular allophony, but rather is more fundamental to dorsal fricative production.

A simplified vocal tract model explores the production of sibilant fricatives

New 3-D rectangular model proves effective in investigating vocal acoustics and production mechanisms.

Speech Adaptation to Kinematic Recording Sensors: Perceptual and Acoustic Findings.

This study used perceptual and acoustic measures to examine the time course of speech adaptation after the attachment of electromagnetic sensor coils to the tongue, lips, and jaw. Twenty native English speakers read aloud stimulus sentences before the attachment of the sensors, immediately after attachment, and again 5, 10, 15, and 20 min later. They read aloud continuously between recordings to encourage adaptation. Sentence recordings were perceptually evaluated by 20 native English listeners, who rated 150 stimuli (which included 31 samples that were repeated to assess rater reliability) using a visual analog scale with the end points labeled as "precise" and "imprecise." Acoustic analysis began by segmenting and measuring the duration of the fricatives /s/ and /ʃ/ as well as the whole sentence. The spectral center of gravity and spectral standard deviation of the 2 fricatives were measured using Praat. These phonetic targets were selected because the standard placement of sensor coils on the lingual surface was anticipated to interfere with normal fricative production, causing them to become distorted. Perceptual ratings revealed a decrease in speech precision after sensor attachment and evidence of adaptation over time; there was little perceptual change beyond the 10-min recording. The spectral center of gravity for /s/ decreased, and the spectral standard deviation for /ʃ/ increased after sensor attachment, but the acoustic measures showed no evidence of adaptation over time. The findings suggest that 10 min may be sufficient time to allow speakers to adapt before experimental data collection with Northern Digital Instruments Wave electromagnetic sensors.

Effects of Two Linguistically Proximal Varieties on the Spectral and Coarticulatory Properties of Fricatives: Evidence from Athenian Greek and Cypriot Greek.

Several studies have explored the acoustic structure of fricatives, yet there has been very little acoustic research on the effects of dialects on the production of fricatives. This article investigates the effects of two linguistically proximal Modern Greek dialects, Athenian Greek and Cypriot Greek on the temporal, spectral, and coarticulatory properties of fricatives and aims to determine the acoustic properties that convey information about these two dialects. Productions of voiced and voiceless labiodental, dental, alveolar, palatal, and velar fricatives were extracted from a speaking task from typically speaking female adult speakers (25 Cypriot Greek and 20 Athenian Greek speakers). Measures were made of spectral properties, using a spectral moments analysis. The formants of the following vowel were measured and second degree polynomials of the formant contours were calculated. The findings showed that Athenian Greek and Cypriot Greek fricatives differ in all spectral properties across all places of articulation. Also, the co-articulatory effects of fricatives on following vowel were different depending on the dialect. Duration, spectral moments, and the starting frequencies of F1, F2, F3, and F4 contributed the most to the classification of dialect. These findings provide a solid evidence base for the manifestation of dialectal information in the acoustic structure of fricatives.

Interdental Fricative Production in Dutch Heritage Language Speakers Living in Canada

This study investigates the production of / θ / and / ð / by three groups of English speakers in the community of Norwich, Ontario, Canada. English monolinguals, Heritage Dutch speakers, and late-learning Dutch L1 English speakers / θ / and / ð / production was measured in both naturalistic and reading tasks. Heritage Dutch speakers produce [θ] and [ð] at similar levels to Monolingual English speakers, the two groups use different allophone inventories especially in the initial position of / ð / and the medial-position of / θ /. This study suggests that despite having native English accents, Dutch Heritage speakers may manipulate the inherently variable English / θ / and / ð / production to communicate their Dutch cultural identity.

Alveolar and Postalveolar Voiceless Fricative and Affricate Productions of Spanish-English Bilingual Children With Cochlear Implants.

This study investigates the production of voiceless alveolar and postalveolar fricatives and affricates by bilingual and monolingual children with hearing loss who use cochlear implants (CIs) and their peers with normal hearing (NH). Fifty-four children participated in our study, including 12 Spanish-English bilingual CI users (M = 6;0 [years;months]), 12 monolingual English-speaking children with CIs (M = 6;1), 20 bilingual children with NH (M = 6;5), and 10 monolingual English-speaking children with NH (M = 5;10). Picture elicitation targeting /s/, /tʃ/, and /ʃ/ was administered. Repeated-measures analyses of variance comparing group means for frication duration, rise time, and centroid frequency were conducted for the effects of CI use and bilingualism. All groups distinguished the target sounds in the 3 acoustic parameters examined. Regarding frication duration and rise time, the Spanish productions of bilingual children with CIs differed from their bilingual peers with NH. English frication duration patterns for bilingual versus monolingual CI users also differed. Centroid frequency was a stronger place cue for children with NH than for children with CIs. Patterns of fricative and affricate production display effects of bilingualism and diminished signal, yielding unique patterns for bilingual and monolingual CI users.

Estimating Vocal Effort from the Aerodynamics of Labial Fricatives: A Feasibility Study

Vocal effort in loud voice is produced with increased subglottal pressure during vowels and increased supraglottal pressure during consonants. In the paper, our main objective is to check whether it was supported by a parallel increase in the airflow resistance of the laryngeal articulator and of the supralaryngeal articulator, here the lips. For this comparison, our choice fell on the fricative consonants, as their production allows perfectly synchronous air pressure and airflow measurements. Also, the calculation of the real instantaneous aerodynamic resistance is possible with fricatives-as it is with vowels-whereas it is not possible with plosives. The present feasibility study on a healthy subject is based on direct subglottal and intraoral pressures and airflow measured for /f/ or /v/ and from the contiguous vowel produced in VCVCV nonsense words at different levels of intensity. The results support that the airflow resistances at the lips and that at the larynx are quite parallel. The airflow resistance at the lips during labial fricative production could provide a good picture of the laryngeal resistance during the production of continuous speech. This suggests clinical applications using both noninvasive inferred measurements of subglottal pressure variation and direct noninferred airflow measurements from more natural speech production tasks.

Acoustic impact of the gradual glottal abduction degree on the production of fricatives: A numerical study.

The paper presents a numerical study about the acoustic impact of the gradual glottal opening on the production of fricatives. Sustained fricatives are simulated by using classic lumped circuit element methods to compute the propagation of the acoustic wave along the vocal tract. A recent glottis model is connected to the wave solver to simulate a partial abduction of the vocal folds during their self-oscillating cycles. Area functions of fricatives at the three places of articulation of French have been extracted from static MRI acquisitions. Simulations highlight the existence of three distinct regimes, named A, B, and C, depending on the degree of abduction of the glottis. They are characterized by the frication noise level: A exhibits a low frication noise level, B, which is a transitional unstable regime, is a mixed noise/voice signal, and C contains only frication noise. They have significant impacts on the first spectral moments. Simulations show that their boundaries depend on articulatory and glottal configurations. The transition regime B is shown to be unstable: it requires very specific configurations in comparison with other regimes, and acoustic features are very sensitive to small perturbations of the glottal configuration abduction in this regime.

Fricative Contrast and Coarticulation in Children With and Without Speech Sound Disorders.

The purpose of this study was, first, to expand our understanding of typical speech development regarding segmental contrast and anticipatory coarticulation, and second, to explore the potential diagnostic utility of acoustic measures of fricative contrast and anticipatory coarticulation in children with speech sound disorders (SSD). In a cross-sectional design, 10 adults, 17 typically developing children, and 11 children with SSD repeated carrier phrases with novel words with fricatives (/s/, /ʃ/). Dependent measures were 2 ratios derived from spectral mean, obtained from perceptually accurate tokens. Group analyses compared adults and typically developing children; individual children with SSD were compared to their respective typically developing peers. Typically developing children demonstrated smaller fricative acoustic contrast than adults but similar coarticulatory patterns. Three children with SSD showed smaller fricative acoustic contrast than their typically developing peers, and 2 children showed abnormal coarticulation. The 2 children with abnormal coarticulation both had a clinical diagnosis of childhood apraxia of speech; no clear pattern was evident regarding SSD subtype for smaller fricative contrast. Children have not reached adult-like speech motor control for fricative production by age 10 even when fricatives are perceptually accurate. Present findings also suggest that abnormal coarticulation but not reduced fricative contrast is SSD-subtype-specific. S1: https://doi.org/10.23641/asha.5103070. S2 and S3: https://doi.org/10.23641/asha.5106508.

Realisation of voicing by French-speaking CI children after long-term implant use: An acoustic study

ABSTRACTStudies of speech production in French-speaking cochlear-implanted (CI) children are very scarce. Yet, difficulties in speech production have been shown to impact the intelligibility of these children. The goal of this study is to understand the effect of long-term use of cochlear implant on speech production, and more precisely on the coordination of laryngeal-oral gestures in stop production. The participants were all monolingual French children: 13 6;6- to 10;7-year-old CI children and 20 age-matched normally hearing (NH) children. We compared /p/, /t/, /k/, /b/, /d/ and /g/ in word-initial consonant-vowel sequences, produced in isolation in two different tasks, and we studied the effects of CI use, vowel context, task and age factors (i.e. chronological age, age at implantation and duration of implant use). Statistical analyses show a difference in voicing production between groups for voiceless consonants (shorter Voice Onset Times for CI children), with significance reached only for /k/, but no difference for voiced consonants. Our study indicates that in the long run, use of CI seems to have limited effects on the acquisition of oro-laryngeal coordination needed to produce voicing, except for specific difficulties located on velars. In a follow-up study, further acoustic analyses on vowel and fricative production by the same children reveal more difficulties, which suggest that cochlear implantation impacts frequency-based features (second formant of vowels and spectral moments of fricatives) more than durational cues (voicing).

The development of gender-specific patterns in the production of voiceless sibilant fricatives in Mandarin Chinese

AbstractThis article reports on the development of gender-specific speech patterns in Mandarin children’s production of voiceless sibilant fricatives. Ninety-four children aged from 2 to 5 (gender-balanced) participated in a word repetition task, producing a series of words beginning with fricatives. Their speech was digitally recorded and acoustically analyzed. The results indicate that gender-related differentiation in /s/ and /ɕ/ occurs around age 4 and becomes more robust at age 5. The differentiation occurs due to the more anterior articulation location that girls employ in their speech in comparison with boys. In addition, 10 adults (gender-balanced) were recorded to probe the origin of this gendered speech phenomenon. Unlike children, adults only show robust gender-related differences in /ɕ/. Results comparing the speech of adults and children suggest that gendered variation in /s/ is potentially the result of a chain shift initiated by gender-linked variation of /ɕ/. These results are discussed with respect to their ramifications for our understanding of the organization and acquisition of multiple components of children’s phonological capacity.

Effects of cosmetic tongue bifurcation on English fricative production

ABSTRACTTongue bifurcation (also called ‘splitting’ or ‘forking’) is an increasingly popular cosmetic procedure in the body modification community that involves splitting the anterior tongue down the centre line. The implications of this procedure for speech have not been systematically studied; a few case studies have been published and suggest that there may be effects, primarily on fricatives. This article presents the first attempt to examine the acoustic implications of tongue bifurcation on speech production using a larger population sample. It compares the speech of 12 individuals with bifurcated tongues with a normative control group of equal size. Both qualitative assessment and quantitative assessment are carried out looking specifically at fricative production and perception. The speech of subjects with bifurcated tongues, while intelligible, shows a higher proportion of perceptibly atypical fricatives and significantly greater variance than seen in the control group.

Fricatives in conversational vs. read speech in mid-Western American English

The present study examines the acoustic characteristics of fricatives across two corpora from mid-Western American English. Our goal is to determine (i) the range of acoustic variation in the production of fricatives in conversational vs. read speech, and (ii) the type and extent of individual variation schemes demonstrated by the speakers. The study surveys over 100,000 fricative tokens from the conversational Buckeye Corpus (Pitt et al. 2005) and the read speech TIMIT Corpus (Zue and Seneff 1988). We test an extensive list of acoustic measures compiled on the basis of prior work with laboratory data (incl. duration, center of gravity, skew, kurtosis, peak power, etc.) and explore the implications of the findings for our understanding of the group and individual patterning of speech production processes across the two different speech styles.

Relationship between auditory degradation and fricatives/affricates production and perception in elderly listeners

Elderly people often complain that they struggle with consonant identification when listening to spoken language. In previous studies, we conducted several experiments, including identification tests for young and elderly listeners using /shi/-/chi/ (CV) and /ishi/-/ichi/ (VCV) continua. We also recorded production of such CV and VCV syllables. For the CV stimuli, confusion of /shi/ as /chi/ increased when the frication had a long rise time. The degree of confusion increased when auditory property degradation was observed such as threshold elevation in high frequency. In the VCV stimuli, confusion of /ichi/ as /ishi/ occurred for a long silent interval between the first V and C with auditory property degradation. In the present study, we analyzed the utterances of those CV and VCV syllables and measured the duration of frication and silent interval. The direction of the boundary shift in the perception of fricatives and affricates by auditory degradation was consistent with that of production. We found that degradation of auditory properties affects both perception and production of fricatives and affricates in elderly people.

Tongue root positioning in English voiced obstruents: Effects of manner and vowel context

Previous research on utterance-initial voiced stops in American English (AE) has shown that speakers enlarge the vocal cavity via tongue root advancement whether or not the stop is phonated when compared to voiceless stops (Ahn 2015). The current ultrasound study expands this line of research to examine two further variables: (a) utterance-initial fricatives/affricates and (b) effect of frontness of the following vowel. Participants included both monolingual (n = 4) and simultaneous bilingual (n = 7) AE speakers. Phrase-initial stops (/p,b,t,d,k,g/), fricatives (/f,v,s,z/), and affricates (/tʃ,ʤ/) were followed by /e/ or /u/. Most productions confirmed that both phonated and unphonated voiced stops/affricates had more tongue root advancement than voiceless ones, but a small proportion showed no difference between phonated, unphonated, and voiceless stops/affricates. Fricative productions were divided between no tongue root difference due to either voicing or phonation, and greater advancement for voiced fricatives regardless of phonation. Tongue root advancement may be less prevalent for fricatives because weakening of the frication can also facilitate the conditions for phonation. A prediction that tongue root advancement for voicing before /e/ might be limited by the positioning requirements of the front vowel was weakly supported, especially for fricatives. The potential effects of bilingual speakers are also addressed.

Spectral dynamics of sibilant fricatives are contrastive and language specific.

Previous research has extensively investigated the spectral properties of sibilant fricatives with little consideration to how these properties vary over time. To investigate such spectro-temporal variation, productions of English /s/ and /ʃ/ and of Japanese /s/ and /ɕ/ in word-initial, prevocalic position were elicited from adult native speakers. The spectral dynamics of these productions were analyzed in terms of a psychoacoustic measure of peak frequency: "peak ERBN number." Peak ERBN number was computed at 17 evenly spaced points across each fricative production. The resulting peak ERBN number trajectories were analyzed with orthogonal polynomial growth-curve models, to determine how peak frequency varied temporally within each fricative. Three analyses compared (1) the English sibilants to each other, (2) the Japanese sibilants to each other, and (3) English /s/ to Japanese /s/. The results indicated that, in both English and Japanese, the sibilant fricatives differ acoustically in terms of both static (i.e., overall level) and dynamic (i.e., shape) aspects of the peak ERBN number trajectories. Furthermore, English /s/ and Japanese /s/ exhibited language-specific differences in the shape, but not overall level, of peak ERBN number trajectories.

Source properties of dorsal fricatives

Present models of voiceless fricative acoustics assume excitation of the vocal cavity anterior to a narrow constriction by an aperiodic source generated from turbulence within that constriction (or in the case of dipole sources from interaction of the jet with an obstacle downstream). This model has been applied successfully to anterior places of articulation (labial to palatal) but for dorsal fricatives, i.e., velar /x/ and uvular /χ/, there is evidence to suggest the assumption of a line source may not hold. Rather, preliminary data from our lab and from studies such as Zeroual (ICPhS, 2003) and Shosted & Chikovani (JIPA, 2006) indicates intermittent presence of a mixed source due to passive vibration of the uvula, yet no study to date has directly addressed this element of the sound source in dorsal fricative production. Acoustic and aerodynamic data on dorsal fricatives produced by four speakers each of Arabic, Persian, and Spanish are presented to validate the nature of the dorsal fricative source component and the degree of cross-linguistic variation in production of these sounds. Measures of periodicity duration and cycle amplitude/shape are employed to estimate the oscillatory pattern of the uvula and model its contribution to the radiated acoustic signal.

Word initial fricative production in children with cochlear implants and their normally hearing peers matched on lexicon size

ABSTRACTFricative production is affected in children with cochlear implants (CI) as compared to age-matched normally hearing (NH) children. However, the phonological development of children with CI is rarely compared to that of NH peers matched on lexicon size. We compare the early word initial fricative development of 10 children with CI and 30 NH children matched on lexicon size and on chronological age. Children with CI are expected to differ from their NH peers when they are matched on chronological age. But, are lexical development and phonological development commensurate in children with CI as they have been shown to be in NH children? Results show that fricative production in children with CI deviates from that of age-matched NH peers. The differences between both groups disappear when they were matched on lexicon size. Thus, phonological development in children with CI is similar to that of their NH peers with comparable lexicon sizes.

Ultrasound and acoustic analysis of sibilant fricatives in preadolescents and adults.

This study describes the production of sibilant fricatives /s/ and /∫/, comparing Scottish English speaking preadolescent children with adults. The materials were the sequences /əCa/ and /əCi/ produced by 15 adults and 15 children aged between 10 and 12 years old. Quantitative analyses were carried out on both spectral information and on ultrasound imaging data on tongue shape, taken from nine successive time points during the fricative. The two groups of speakers were very similar to each other in the articulatory and acoustic characteristics distinguishing the two fricatives. Age-related differences in the fricative centroid measure occurred at consonant-vowel boundaries, with lower values in the preadolescents. Within-speaker variability was mostly similar across age groups, with the exception of the fricative centroid for /∫/, which was significantly more variable in preadolescents than in adults. Throughout the consonant duration, both groups consistently differentiated between the two consonants in both the fricative centroid and in one measure of tongue shape.

Production of word-initial fricatives of Mandarin Chinese in prelingually deafened children with cochlear implants

Purpose: This study examined the production of fricatives by prelingually deafened Mandarin-speaking children with cochlear implants (CIs).Method: Fourteen cochlear implant (CI) children (2.9–8.3 years old) and 60 age-matched normal-hearing (NH) children were recorded producing a list of 13 Mandarin words with four fricatives, /f, s, ɕ, ʂ/, occurring at the syllable-initial position evoked with a picture-naming task. Two phonetically-trained native Mandarin speakers transcribed the fricative productions. Acoustic analysis was conducted to examine acoustic measures including duration, normalised amplitude, spectral peak location and four spectral moments.Result: The CI children showed much lower accuracy rates and more diverse error patterns on all four fricatives than their NH peers. Among these four fricatives, both CI and NH children showed the highest rate of mispronunciation of /s/. The acoustic results showed that the speech of the CI children differed from the NH children in spectral peak location, normalised amplitude, spectral mean and spectral skewness. In addition, the fricatives produced by the CI children showed less distinctive patterns of acoustic measures relative to the NH children.Conclusion: In general, these results indicate that the CI children have not established distinct categories for the Mandarin fricatives in terms of the place of articulation.