Degree Of Coarticulation Research Articles

Impact of prominence type on the coarticulation of vowels following palatalized consonants

The quantitative impact of prominence (neutral vs emphatic stress) on the coarticulation of the Russian low [æ], mid [e] and high [i] front vowels is evaluated in CV sequences with palatalized consonants of various places of obstruction. The research is conditioned by the aims of speech synthesis and recognition of the Russian language, the current data in the field being insufficient. First order linear equations (locus equations) are used to evaluate the degree of CV coarticulation. The experiment is performed on CjVCjV nonsense words imbedded in the middle position of a carrier phrase «Vyros CVCV sjyljnym» («CjVCjV has grown up strong»). The first syllable of the target words was uttered both with neutral and emphatic stress. The Praat software was used to measure F2 formant values at vowel onsets and central parts. It was established that linear regression slopes are similar both in the Y-intercepts and slope coefficients for the palatalized consonants of various places of obstruction uttered with the same prominence. The degree of coarticulation was different depending upon the type of prominence (neutral or emphatic): the coefficients were lower in case of the emphatic stress compared to those of the neutral one. ANOVA analysis and Student’s t-test were performed to reveal the difference in F2 values of vowel onsets and middle parts as a function of the vowel openness and type of prominence. The results obtained were interpreted based on the degree of the openness of the vowels under study: an open vowel under emphatic stress tends to expand its vowel space by a backward displacement while close vowels tend to move forward in the mouth cavity when pronounced with emphatic stress.

An Airflow Analysis of Spanish and English Anticipatory Vowel Nasalization among Heritage Bilinguals

Gestural timing overlap between a vowel and subsequent nasal consonant results in the vowel being articulatorily nasalized. Research has shown that such degree of coarticulation varies cross-linguistically (e.g., English exhibits a greater gestural timing overlap than Spanish). This phenomenon has mainly been investigated in monolingual samples, and with only a small number of studies focusing on second and heritage language gestural timing patterns of nasality; the role of bilingualism in this respect is thus an open question, which is the focus of the current study. Sixteen second-generation US-born heritage bilinguals participated in this experiment. Their degree of bilingualism was assessed via the Bilingual Language Profile. They completed two separate read-aloud tasks: one in Spanish (heritage language) and one in English (second language). Simultaneous oral and nasal airflow were collected via pressure transducers from words that included phonetically oral and nasalized vowels. Results indicate that heritage bilinguals increment the degree of vocalic nasalization from Spanish to English. Nevertheless, their degree of bilingualism did not yield statistical significance in phonetic performance. The current study is the first one implementing aerodynamic methods with a heritage bilingual population and presents data for the possibility to possess two segment-to-segment timing strategies in heritage grammars.

What Do Differences between Alternating and Sequential Diadochokinetic Tasks Tell Us about the Development of Oromotor Skills? An Insight from Childhood to Adulthood.

Oral diadochokinetic (DDK) tasks are common research and clinical tools used to test oromotor skills across different age groups. They include alternating motion rate (AMR) and sequential motion rate (SMR) tasks. AMR tasks involve repeating a single syllable, whereas SMR tasks involve repeating varying syllables. DDK performance is mostly discussed regarding the increasing rates of AMR and SMR tasks from childhood to adulthood, although less attention is given to the performance differences between SMR and AMR tasks across age groups. Here, AMR and SMR syllabic rates were contrasted in three populations: 7-9-year-old children, 14-16-year-old adolescents and 20-30-year-old adults. The results revealed similar syllabic rates for the two DDK tasks in children, whereas adolescents and adults achieved faster SMR rates. Acoustic analyses showed similarities in prosodic features between AMR and SMR sequences and in anticipatory coarticulation in the SMR sequences in all age groups. However, a lower degree of coarticulation was observed in children relative to adults. Adolescents, on the contrary, showed an adult-like pattern. These findings suggest that SMR tasks may be more sensitive to age-related changes in oromotor skills than AMR tasks and that greater gestural overlap across varying syllables may be a factor in achieving higher rates in SMR tasks.

Speakers coarticulate less in response to both real and imagined communicative challenges: An acoustic analysis of the LUCID corpus

Overlap of adjacent articulatory gestures leads to coarticulation. Understanding how hyperarticulated intelligibility-enhancing clear speech modifications affect coarticulation can inform theories of phonetic variation and speech intelligibility. However, prior research yielded mixed findings regarding the relationship between hyperarticulation and coarticulatory patterns. This study extends previous work by analyzing the degree of coarticulation across several different communicative conditions in the LUCID corpus (Baker & Hazan, 2010). Southern British English speakers completed an interactive spot-the-difference task with a partner with and without a communicative barrier (e.g., speech degraded by talker babble). They also read sentences without an interlocutor casually and clearly. Diphones in keywords produced in both tasks were analyzed using two whole-spectrum measures, with greater spectral distance and shorter coarticulatory overlap between the diphones indexing less coarticulation. Results revealed that speakers coarticulated less in response to both real (interactive task) and imaginary (sentence-reading) communicative challenges. Speakers furthermore varied the degree of coarticulatory resistance in different real communicative barriers. Diphones with greater consonant articulatory constraint were less sensitive to differences between the conditions, suggesting a limit to the hyperarticulation-induced phonetic variation. The findings agree with the models of targeted speaker adaptations assuming coarticulatory resistance in hyperarticulated clear speech (the H&H theory: Lindblom, 1990).

Analysis of Second and Third Formant Locus Pattern and C-V Coarticulation in EkeGusii

This study analyses locus equations and regression lines relating to second and third formants as a measure of co-articulatory influence of vowels following stop consonants in EkeGusii. Coarticulation can be represented statistically using a schematic representation of locus equations by tracking consonant-vowel (CV) transition as a useful tool in the discrimination of place of articulation. Acoustic data was collected using Praat version 6.0 from four males and four females, native speakers of EkeGusii. Locus equations for the eight speakers were derived from CV words with intervocalic voiceless bilabial /p/, voiceless alveolar /t/ and voiceless velar /k/ preceding vowel /i/, /a/ and /o/ contexts. Scatter plots of locus equation of F2 and F3 onsets-F2 and F3 midpoints revealed patterns for each of the three voiceless stops in EkeGusii. The strongest degree of coarticulation is reported for velars then bilabials and the least degree of coarticulation with alveolars.

Lithuanian and Latvian laterals: Comparison of acoustic properties

The aim of the paper is to examine how acoustic contrast manifests itself between /l/ and /ʎ/ in Latvian, as well as /l/ and /lʲ/ in Lithuanian. For the study, speech recordings of 6 adult informants (3 Lithuanian and 3 Latvian male speakers) have been analysed. Initial and final laterals in closed symmetric [l]V[l] sequences and intervocalic syllable-initial laterals in V[l]V sequences have been examined. During the analysis, the focus is placed mainly on locus equations, as well as changes in formant structure (especially F1 and F2) triggered by position and vocalic context. Acoustic data demonstrates differences in coarticulation effects between Latvian palatal /ʎ/ and Lithuanian palatalized /lʲ/. The formant structure of /ʎ/ and /lʲ/, unlike the corresponding non-palatal laterals, is more stable and less dependent on the quality of adjacent vowels. Vowel context affects the degree of palatalization, e. g. palatalized [lʲ] next to [ɪ], [iː] and [eː] is pronounced “softer” than next to [ɔ̟], [o̟ː], [ʊ̟], and [u̟ː]. Latvian /ʎ/ is characterized by a more stable vowel F2 locus, which indicates higher degree of coarticulatory resistance to vowel effects; the quality of /lʲ/, on the contrary, depends more on vowel context. The same is true (although to lesser degree) for the Lithuanian /l/. The assumption about the similarity of Latvian non-palatal /l/ and Lithuanian palatalized /lʲ/ is only partly supported by the recent data. In terms of the degree of coarticulation (indicated by slope values of locus equations), Latvian /l/ is closer to Lithuanian /lʲ/, while its formant structure, especially low F2, brings it closer to Lithuanian /l/.

Developmental Changes in Coarticulation Degree Relate to Differences in Articulatory Patterns: An Empirically Grounded Modeling Approach.

Coarticulatory effects in speech vary across development, but the sources of this variation remain unclear. This study investigated whether developmental differences in intrasyllabic coarticulation degree could be explained by differences in children's articulatory patterns compared to adults. To address this question, we first compared the tongue configurations of 3- to 7-year-old German children to those of adults. The observed developmental differences were then examined through simulations with Task Dynamics Application, a Task Dynamics simulation system, to establish which articulatory modifications could best reproduce the empirical results. To generate syllables simulating the lack of tongue gesture differentiation, we tested three simulation scenarios. We found that younger speakers use less differentiated articulatory patterns to achieve alveolar constrictions than adults. The simulations corresponding to undifferentiated control of tongue tip and tongue body resulted in (a) tongue shapes similar to those observed in natural speech and (b) higher degrees of intrasyllabic coarticulation in children when compared to adults. Results provide evidence that differences in articulatory patterns contribute to developmental differences in coarticulation degree. This study further shows that empirically informed modeling can advance our understanding of changes in coarticulatory patterns across age.

Зависимость степени коартикуляции согласного и гласного от типа ударения

The paper evaluates the quantitative impact of prominence (neutral vs emphatic stress) in CV sequences. The study serves the practical needs of speech synthesis and recognition and attempts to fill an important gap as there is insufficient research in the field with regard to the Russian language. We used the locus equation method to assess the degree of CV coarticulation. The experiment was performed on CVCV nonsense words imbedded in the middle position of a carrier phrase. The first syllable of the target words was made prominent both with neutral and emphatic stress. The consonants and vowels were presented by the same consonant and vowel sounds. Russian voiced occlusive bilabial, forelingual and backlingual consonants [b], [d] and [ɡ] were combined with Russian non-palatal vowels [ɛ], [ɑ] and [u] occupying cardinal positions in the Fant triangle. Six male speakers were recorded in a sound attenuated studio using high-quality recording equipment. The total number of tokens N = 486. Praat software was used to measure formant frequencies by means of fast Fourier transformation and linear predictive coding. The experiment showed that linear regression slopes differed both in the Y-intercepts and slope coefficients for the vowels uttered with emphatic and neutral stress. We compared locus equation slopes for CV transitions of the consonants of similar place of obstruction combined with the vowels pronounced with neutral and emphatic stress, which revealed a quantitative difference in the degree of coarticulation of the bilabial and forelingual consonants both in the Y-intercept values and slope coefficients. In case of the backlingual consonant, locus equations differed only in the Y-intercept value, while the slope coefficients were practically the same. The results obtained were interpreted on the basis of existing experimental data for the Russian, English, and Arabic languages.

Phonetic detail encoding in explaining boundary-modulated coarticulation

This study examines the acoustic outputs in boundary coarticulation and attempts to explain the native and nonnative production differences in relation to speech planning. English consonant clusters across words produced by English (L1) and Mandarin (L2) speakers are analyzed. This study focuses on two segmental features (place of articulation and voicing) and computes three acoustic-based measurements (internal release, closure durations and closure shortening). The results find a lesser coarticulation degree in L2 production, and differing acoustic deviations varying with speakers’ proficiency level. The results also suggest that cross-word planning involving place of articulation is robust in both L1 and L2 production, while cross-word voicing encoding is not available in L2 speech. The asymmetry in L2 encoding is compatible with a competitive gestural selection analysis, and the implications of L1 production have been interpreted as in favor of a richer mental representation and finer-level execution than the syllable-sized programming. The preliminary results support the core assumption that L1 and L2 coarticulation differences arise from phonological and phonetic encoding. This study adds cross-linguistic output-based evidence on speech planning and encourages speech models to further specify the very late stage of phonetic encoding.

Coarticulatory Aspects of the Fluent Speech of French and Italian People Who Stutter Under Altered Auditory Feedback.

A number of studies have shown that phonetic peculiarities, especially at the coarticulation level, exist in the disfluent as well as in the perceptively fluent speech of people who stutter (PWS). However, results from fluent speech are very disparate and not easily interpretable. Are the coarticulatory features observed in fluent speech of PWS a manifestation of the disorder, or rather a compensation for the disorder itself? The purpose of the present study is to investigate the coarticulatory behavior in the fluent speech of PWS in the attempt to answer the question on its symptomatic or adaptive nature. In order to achieve this, we have studied the speech of 21 adult PWS (10 French and 11 Italian) compared to that of 20 fluent adults (10 French and 10 Italian). The participants had to repeat simple CV syllables in short carrier sentences, where C = /b, d, g/ and V = /a, i, u/. Crucially, this repetition task was performed in order to compare fluent speech coarticulation of PWS to that of PWNS, and to compare the coarticulation of PWS under a condition with normal auditory feedback (NAF) and under a fluency-enhancing condition due to an altered auditory feedback (AAF). This is the first study, to our knowledge, to investigate the coarticulation behavior under AAF. The degree of coarticulation was measured by means of the Locus Equations (LE). The coarticulation degree observed in fluent PWS speech is lower than that of the PWNS, and, more importantly, in AAF condition, PWS coarticulation appears even weaker than in the NAF condition. The results allow to interpret the lower degree of coarticulation found in fluent speech of PWS under NAF condition as a compensation for the disorder, based on the fact that PWS’s coarticulation is weakening in fluency-enhancing conditions, further away from the degree of coarticulation observed in PWNS. Since a lower degree of coarticulation is associated to a greater separation between the places of articulation of the consonant and the vowel, these results are compatible with the hypothesis that larger articulatory movements could be responsible for the stabilization of the PWS speech motor system, increasing the kinesthetic feedback from the effector system. This interpretation shares with a number of relatively recent proposal the idea that stuttering derives from an impaired feedforward (open-loop) control system, which makes PWS rely more heavily on a feedback-based (closed loop) motor control strategy.

Degree of Articulatory Dispersion: An Introduction to a Model of Coarticulation

The purpose of the study is to introduce a new Model of Coarticulation, namely, Degree of Articulatory Dispersion. This paper reviews the Models of Coarticulation, and then the validity of the Degree of Articulatory Dispersion is proved by finding the correlation between the dispersion of DAD and the slope of LEM in the four groups of Monguor consonants classified by the manner of articulation. The finding shows that there is a significant negative correlation between the dispersion of DAD and the slope of LEM. Therefore, Degree of Articulatory Dispersion can be a valid Model of Coarticulation to measure the degree of coarticulation.

Spoken Language Development and the Challenge of Skill Integration.

The development of phonological awareness, the knowledge of the structural combinatoriality of a language, has been widely investigated in relation to reading (dis)ability across languages. However, the extent to which knowledge of phonemic units may interact with spoken language organization in (transparent) alphabetical languages has hardly been investigated. The present study examined whether phonemic awareness correlates with coarticulation degree, commonly used as a metric for estimating the size of children’s production units. A speech production task was designed to test for developmental differences in intra-syllabic coarticulation degree in 41 German children from 4 to 7 years of age. The technique of ultrasound imaging allowed for comparing the articulatory foundations of children’s coarticulatory patterns. Four behavioral tasks assessing various levels of phonological awareness from large to small units and expressive vocabulary were also administered. Generalized additive modeling revealed strong interactions between children’s vocabulary and phonological awareness with coarticulatory patterns. Greater knowledge of sub-lexical units was associated with lower intra-syllabic coarticulation degree and greater differentiation of articulatory gestures for individual segments. This interaction was mostly nonlinear: an increase in children’s phonological proficiency was not systematically associated with an equivalent change in coarticulation degree. Similar findings were drawn between vocabulary and coarticulatory patterns. Overall, results suggest that the process of developing spoken language fluency involves dynamical interactions between cognitive and speech motor domains. Arguments for an integrated-interactive approach to skill development are discussed.

Effects of prosody on acquisition of anticipatory coarticulation by Italian-speaking children

This study investigates patterns of acquisition of anticipatory lingual coarticulation by children in Typical Development (TD) and with Speech Sound Disorders (SSD): contradictory data have detected different degrees of coarticulation in children versus adults. This research brings evidence from Italian-speaking children, and analyzes also effects of prosody on development of coarticulation. 2 Italian-speaking SSD and 2 TD, 6-8 years, pronounced disyllabic non-words of different stress structure ([pV’tV] and [pVtV’]), upon elicitation by 2 adults. Both CV and V-V anticipatory coarticulation were measured, by (1) locus equations on CV sequences, indicative of regular patterns of stop-consonant interaction with different vowels; (2) trajectories (extent and duration) and slope index (extent/duration) of V-V F2 transitions. Preliminary results based on locus equations scatterplot and regression lines slope coefficients, show similar degree of coarticulation in TD and SSD versus adults in unstressed CV condition, but higher slope values (greater anticipatory coarticulation) in SSD, in stressed CV position. These findings suggest that (a) similar patterns of emergence of anticipatory coarticulation appear in TD versus SSD versus adults, in unstressed condition, with a slightly greater degree of coarticulation in SSD versus TD (b) prosodic factors seem to affect acquisition of coarticulation in SSD.

On the development of gestural organization: A cross-sectional study of vowel-to-vowel anticipatory coarticulation.

In the first years of life, children differ greatly from adults in the temporal organization of their speech gestures in fluent language production. However, dissent remains as to the maturational direction of such organization. The present study sheds new light on this process by tracking the development of anticipatory vowel-to-vowel coarticulation in a cross-sectional investigation of 62 German children (from 3.5 to 7 years of age) and 13 adults. It focuses on gestures of the tongue, a complex organ whose spatiotemporal control is indispensable for speech production. The goal of the study was threefold: 1) investigate whether children as well as adults initiate the articulation for a target vowel in advance of its acoustic onset, 2) test if the identity of the intervocalic consonant matters and finally, 3) describe age-related developments of these lingual coarticulatory patterns. To achieve this goal, ultrasound tongue imaging was used to record lingual movements and quantify changes in coarticulation degree as a function of consonantal context and age. Results from linear mixed effects models indicate that like adults, children initiate vowels’ lingual gestures well ahead of their acoustic onset. Second, while the identity of the intervocalic consonant affects the degree of vocalic anticipation in adults, it does not in children at any age. Finally, the degree of vowel-to-vowel coarticulation is significantly higher in all cohorts of children than in adults. However, among children, a developmental decrease of vocalic coarticulation is only found for sequences including the alveolar stop /d/ which requires finer spatiotemporal coordination of the tongue’s subparts compared to labial and velar stops. Altogether, results suggest greater gestural overlap in child than in adult speech and support the view of a non-uniform and protracted maturation of lingual coarticulation calling for thorough considerations of the articulatory intricacies from which subtle developmental differences may originate.

How Do Children Organize Their Speech in the First Years of Life? Insight From Ultrasound Imaging.

This study reports on a cross-sectional investigation of lingual coarticulation in 57 typically developing German children (4 cohorts from 3.5 to 7 years of age) as compared with 12 adults. It examines whether the organization of lingual gestures for intrasyllabic coarticulation differs as a function of age and consonantal context. Using the technique of ultrasound imaging, we recorded movement of the tongue articulator during the production of pseudowords, including various vocalic and consonantal contexts. Results from linear mixed-effects models show greater lingual coarticulation in all groups of children as compared with adults with a significant decrease from the kindergarten years (at ages 3, 4, and 5 years) to the end of the 1st year into primary school (at age 7 years). Additional differences in coarticulation degree were found across and within age groups as a function of the onset consonant identity (/b/, /d/, and /g/). Results support the view that, although coarticulation degree decreases with age, children do not organize consecutive articulatory gestures with a uniform organizational scheme (e.g., segmental or syllabic). Instead, results suggest that coarticulatory organization is sensitive to the underlying articulatory properties of the segments combined.

Spectral Coefficient Analyses of Word-Initial Stop Consonant Productions Suggest Similar Anticipatory Coarticulation for Stuttering and Nonstuttering Adults.

A longstanding hypothesis about the sensorimotor mechanisms underlying stuttering suggests that stuttered speech dysfluencies result from a lack of coarticulation. Formant-based measures of either the stuttered or fluent speech of children and adults who stutter have generally failed to obtain compelling evidence in support of the hypothesis that these individuals differ in the timing or degree of coarticulation. Here, we used a sensitive acoustic technique-spectral coefficient analyses-that allowed us to compare stuttering and nonstuttering speakers with regard to vowel-dependent anticipatory influences as early as the onset burst of a preceding voiceless stop consonant. Eight adults who stutter and eight matched adults who do not stutter produced C1VC2 words, and the first four spectral coefficients were calculated for one analysis window centered on the burst of C1 and two subsequent windows covering the beginning of the aspiration phase. Findings confirmed that the combined use of four spectral coefficients is an effective method for detecting the anticipatory influence of a vowel on the initial burst of a preceding voiceless stop consonant. However, the observed patterns of anticipatory coarticulation showed no statistically significant differences, or trends toward such differences, between the stuttering and nonstuttering groups. Combining the present results for fluent speech in one given phonetic context with prior findings from both stuttered and fluent speech in a variety of other contexts, we conclude that there is currently no support for the hypothesis that the fluent speech of individuals who stutter is characterized by limited coarticulation.

The acoustic counterpart to articulatory resistance and aggressiveness in locus equation metrics and vowel dispersion

Research on locus equation metrics (LEs) tend to take it for granted that vowel space is invariable across consonantal contexts. However, articulation-based studies report a mutual influence between neighboring segments such that segments with greater constraints in dorsal articulation are more resistant to and concurrently more aggressive in coarticulation than those with less constraints (Farnetani, 1990). We examine (1) whether articulatory resistance and aggressiveness can be acoustically captured through LEs and vowel dispersion and (2) how the relationship between LEs and the degree of coarticulation is mediated by vowel dispersion and delay in voicing. These questions are investigated in CV sequences in English –where C is one of /p t s ʃ/ that varies in the articulatory constraints imposed on the tongue dorsum. We manipulated the magnitude of coarticulation and voicing lag by contrastively stressing the target consonants. Our results show that there is a tight relationship between LE slopes and vowel dispersion where articulatory resistance and aggressiveness appear as the mirror image of each other in the acoustic signal. However, effects of hyperspeech simultaneously affect vowel dispersion, voicing delay, and LEs creating confounds. This calls for caution in the use of LE metrics as a measure of coarticulation.

Modeling the gradient evolution and decay of harmony systems

The diachronic trajectories of vowel harmony systems have been understudied but offer significant insight into both the possible domains of vowel harmony as well as the interaction between phonetic coarticulation and phonological harmony. This paper proposes a novel analysis of decaying labial harmony in Kazakh, unifying phonetics and phonology in one formalism (Flemming 2001) that incorporates both abstract morpho-phonological and temporal phonetic factors to drive the gradient harmony pattern in contemporary Kazakh. These factors are defined and implemented in a regression-like model that accurately predicts the degree of coarticulation on non-initial vowels. The structure of the model is then discussed in diachronic terms, outlining the development and decline of harmony, as predicted by the model. Significantly, these predictions are supported by typologically attested domains of harmony among the world’s languages. The model developed herein is thus able to accurately predict the fine-grained degree of coarticulation in Kazakh, as well as suggest a plausible pathway for the evolution and decay of harmony patterns more broadly.The diachronic trajectories of vowel harmony systems have been understudied, but offer significant insight into both the possible domains of vowel harmony as well as the interaction between phonetic coarticulation and phonological harmony. This paper proposes a novel analysis of decaying labial harmony in Kazakh, unifying phonetics and phonology in one formalism (Flemming 2001) that incorporates both abstract morpho-phonological and temporal phonetic factors to drive the gradient harmony pattern in contemporary Kazakh. These factors are defined and implemented in a regression-like model that accurately predicts the degree of coarticulation on non-initial vowels. The structure of the model is then discussed in diachronic terms, outlining the development and decline of harmony, as predicted by the model. Significantly, these predictions are supported by typologically attested domains of harmony among the world’s languages. The model developed herein is thus able to accurately predict the fine-grained degree of coarticulation in Kazakh, as well as suggest a plausible pathway for the evolution and decay of harmony patterns more broadly.

The Korean Prevocalic Palatal Glide: A Comparison with the Russian Glide and Palatalization

Phonetic studies of the Korean prevocalic glides have often suggested that they are shorter in duration than those of languages like English, and lack a prolonged steady state. In addition, the formant frequencies of the Korean labiovelar glide are reported to be greatly influenced by the following vowel. In this study the Korean prevocalic palatal glide is investigated vis-à-vis the two phonologically similar configurations of another language - the glide /j/ and the secondary palatalization of Russian, with regard to the inherent duration of the glide component, F2 trajectory, vowel-to-glide coarticulation and glide-to-vowel coarticulation. It is revealed that the Korean palatal glide is closer to the Russian palatalization in duration and F2 trajectory, indicating a lack of steady state, and to the Russian segmental glide in the vowel-to-glide coarticulation degree. When the glide-to-vowel coarticulation is considered, the Korean palatal glide is distinguished from both Russian categories. The results suggest that both the Korean palatal glide and the Russian palatalization involve significant articulatory overlap, the former with the vowel and the latter with the consonant. Phonological implications of such a difference in coarticulation pattern are discussed, as well as the comparison between the Korean labiovelar and palatal glides.

CV coarticulation, locus and locus equation perspective on the invariance issue involving Algerian Arabic consonants

The aim of the present investigation is to strengthen the link between coarticulation and locus theory of speech perception through the analysis and discrimination of six Algerian Arabic consonants [b], [d], [ɡ], [q], [ʕ], [h] representing respectively six places of articulation: labial, alveolar, velar, uvular, pharyngeal, laryngeal. When plotting the error area of the categories formed by (F2onset, F3onset) samples within a CV syllable across all speakers against the F2 transition extent mean(abs(F2onset–F2vowel)), a linear correlation is observed. Then a formula for the degree of coarticulation is derived from this straight line and it is shown that it is more reliable than the slope of the locus line. When combined with the locus equation's linearity, another equation is obtained and appears to be well fitted with locus theory. Another observation in our data concerns the deviation of syllables with respect to the locus line, as in the previously noted case of [ɡ] with back vowels. Moreover, it is shown that these shifts are speaker dependent and a consequence of interactions between the categories cited above. Finally, it is shown how better place separation is obtained when these categories are mapped in the auditor's perception space using the modified locus equation.