An evaluation of several methods for computing lingual coarticulatory resistance using ultrasound.

The paper evaluates the efficiency of six computation methods in distinguishing lingual coarticulatory resistance among consonants and vowels using ultrasound data. This research goal is tested on a corpus of symmetrical vowel-consonant-vowel sequences composed of 10 consonants and five vowels produced by five Catalan speakers. Results show that, while the coarticulatory resistance hierarchies obtained by all methods conform largely to the predictions of the degree of articulatory constraint model of coarticulation, some (i.e., area of the articulatory zone, mean point-by-point coefficient of variation, and mean nearest neighbour distance) are somewhat more highly predictive than others (i.e., locus equation, mutual information, and highest point of the tongue dorsum). Methods differ mostly regarding the classification of consonants exhibiting intermediate degrees of coarticulatory resistance due to the way the methods have been designed. The implications of these findings for research on dialectal variation are discussed.

Lingual Articulation and Coarticulation for Catalan Consonants and Vowels: An Ultrasound Study.

BACKGROUND: The study investigates the tongue position and coarticulatory characteristics of a subset of Catalan consonants and vowels using ultrasound. METHOD: Ultrasound data were recorded and analyzed for the Catalan front lingual consonants /t, d, n, l, ɾ, s, r, ʎ, ɲ, ʃ/ and vowels /i, e, a, o, u/ in symmetrical VCV sequences produced by 5 adult Catalan speakers. RESULTS: Among other aspects, data show more tongue body fronting for palatal consonants and, among dentals and alveolars, for laminals than for apicals; the manner of articulation demands account for considerable tongue body retraction and predorsum lowering during the trill /r/ and for some tongue body retraction during /l/ next to front vowels. Vowel and consonant coarticulation occurs mostly in lingual regions which are not primarily involved in closure or constriction formation. Differences in the relative prominence of the anticipatory and carryover consonant-to-vowel effects in tongue body position were found to hold clearly for /r/ in all vowel contexts and for palatal consonants next to /a, o, u/. CONCLUSIONS: Place-dependent and manner-dependent articulatory characteristics for consonants and vowels account for the most relevant coarticulatory effects and may contribute to explain several sound change patterns.

The Effect of Contextual Consonants on Voiced Stop Lenition: Evidence from Catalan.

Abstract This study uses acoustic energy measures for /b, d, g/ after /f, s, ∫, l, r/ in Catalan in order to test whether postconsonantal voiced stop lenition is ruled by minimization of articulatory effort, acoustico-perceptual continuity of an ongoing prosodic constituent or some other principle of articulatory organization. Data for eight speakers reveal that lenition is more prone to operate on /g/ than on /b, d/, after a sonorant than after a fricative, and when the two cluster consonants are heterorganic than when they are (quasi)-homorganic. Moreover, a positive correlation was found to hold between the degrees of stop lenition and stop voicing. The /fC/ sequences had an exceptional behaviour since, in comparison to other consonants appearing in CI position, /f/ was at the same time less intense and triggered more stop-like realizations of /b, d, g/. These results indicate that, while regularly treated as a phonological process, postconsonantal voiced stop lenition in Catalan is subject to much contextual variability, and should be dealt with by a production-based model which takes into consideration several articulatory and aerodynamic factors such as constriction degree and intraoral pressure level for C1 and C2, as well as homorganicity degree between the two consecutive consonants.

The Effect of Stress and Speech Rate on Vowel Coarticulation in Catalan Vowel-Consonant-Vowel Sequences.

PURPOSE: The goal of this study was to ascertain the effect of changes in stress and speech rate on vowel coarticulation in vowel-consonant-vowel sequences. METHOD: Data on second formant coarticulatory effects as a function of changing /i/ versus /a/ were collected for five Catalan speakers' productions of vowel-consonant-vowel sequences with the fixed vowels /i/ and /a/ and consonants: the approximant /δ/, the alveolopalatal nasal /ɲ/, and /l/, which in the Catalan language differs in darkness degree according to speaker. RESULTS: In agreement with predictions formulated by the degree-of-articulation-constraint model of coarticulation, the size of the vowel coarticulatory effects was inversely related to the degree of articulatory constraint for the consonant, and the direction of those effects was mostly carryover or anticipatory in vowel-consonant-vowel sequences with highly constrained consonants (/ɲ/, dark /l/) and more variable whenever the intervocalic consonant was less constrained (/δ/, clear /l/). Stress and speech-rate variations had an effect on overall vowel duration, second formant frequency, and coarticulation size but not on the consonant-specific patterns of degree and direction of vowel coarticulation. CONCLUSION: These results indicate that prosodically induced coarticulatory changes conform to the basic principles of segmental coarticulatory organization.

Articulatory reduction and coarticulation in Catalan three-consonant sequences.

Electropalatographic and acoustic data on Catalan /Ck#C/ sequences where # is a word boundary and /k/ is preceded by /l, s, r/ and followed by /b, m, d, l, n, z, r, ʎ/ were collected in order to test the hypothesis that the velar stop is most prone to be reduced and deleted next to consonants involving high articulatory and aerodynamic demands. Analysis results reveal the absence of a velar stop closure in about half of the sequence tokens, mostly so when /k/ occurs after /s/ and before an oral stop presumably due to the high manner of articulation requirements involved. On the other hand, /Ck#C/ sequences where a /k/ closure period is available show a prominent realization of the velar stop mostly next to /s, z/. This scenario points to two different production mechanisms for three-consonant sequences with contextual obstruents: articulatory reduction and elision, and a slowing down and an increase in articulatory salience, of the velar stop. /Ck#C/ sequences lacking an acoustic closure for /k/ were found to show a residual velar stop articulation which was implemented through an increase in cluster duration and in dorsopalatal contact at the approximate /k/ location in comparison to identical /C#C/ sequences with no /k/.

Gradient phonetic implementation of regressive voicing assimilation in Catalan heterosyllabic two- and three-consonant clusters.

Electroglottographic data for word-final obstruents in C#C and CC#C sequences with a word-initial voiced consonant indicate that regressive voicing adaptation is a categorical and thus assimilatory process for most Catalan speakers. Word-final obstruents are planned as voiced since they exhibit full voicing or else an initial voicing period which is longer than the voicing lag associated with the vowel preceding the cluster. Segmental duration may also be used by speakers for realizing word-final obstruents as voiced in C#C but not in CC#C clusters. The phonetic implementation of voicing assimilation proceeds gradually: voicing for word-final obstruents differs considerably among speakers and is less for fricatives than for stops and whenever the word-initial consonant is an obstruent or an approximant than when it is a nasal, a lateral or an alveolar trill. The study also reveals that those C1 realizations which are less prone to acquire voicing show more token-totoken variability in voicing and segmental duration and therefore appear to be less tightly controlled by speakers. In conjunction with data from other studies, these Catalan data suggest that speakers and languages with prevoiced stops may differ with respect to the more or less gradient phonetic implementation of the regressive voicing assimilation process in heterosyllabic consonant clusters.

The coarticulation/invariance scale: mutual information as a measure of coarticulation resistance, motor synergy, and articulatory invariance.

Coarticulation and invariance are two topics at the center of theorizing about speech production and speech perception. In this paper, a quantitative scale is proposed that places coarticulation and invariance at the two ends of the scale. This scale is based on physical information flow in the articulatory signal, and uses Information Theory, especially the concept of mutual information, to quantify these central concepts of speech research. Mutual Information measures the amount of physical information shared across phonological units. In the proposed quantitative scale, coarticulation corresponds to greater and invariance to lesser information sharing. The measurement scale is tested by data from three languages: German, Catalan, and English. The relation between the proposed scale and several existing theories of coarticulation is discussed, and implications for existing theories of speech production and perception are presented.

Coarticulation in Catalan dark [l] and the alveolar trill: general implications for sound change.

Coarticulation data for Catalan reveal that, while being less sensitive to vowel effects at the consonant period, the alveolar trill [r] exerts more prominent effects than [l] on both adjacent [a] and [i]. This coarticulatory pattern may be related to strict manner demands on the production of the trill. Both consonants also differ regarding the relative prominence of the consonant-to-vowel anticipatory and carryover effects in VCV sequences: while [r] and [l] exert much anticipatory coarticulation on the preceding vowel, carryover effects on the following vowel turn out to be more salient for [r] than for [l]. These consonant-dependent differences in coarticulatory direction parallel the directionality patterns observed in related vowel assimilatory and glide insertion processes occurring in the Romance languages, in Early Germanic, in Old, Middle and Modern English, and in Arabic when the target consonant is not [l] or [r] but a pharyngealized dentoalveolar.

An articulatory and acoustic study of the fricative clusters /sʃ/ and /ʃs/ in Catalan.

Elect ropalatographic and acoustic data for the fricative clusters /sʃ/ and /ʃs/ and the single fricatives /s/ and /ʃ/ in Eastern Catalan reveal that, while /sʃ/ undergoes regressive assimilation, /ʃs/ blends into an intermediate fricative or exhibits a twotarget realization. On the other hand, acoustic data for /ʃs/ in Western Catalan show that /s/ may assimilate to preceding /ʃ/ or undergo blending or a two-target realization depending on speaker and prosodic condition (no data are available for /sʃ/ in this dialect). Duration values for the two fricative clusters suggest that the assimilated outcome of /sʃ/ shortens down to the length of /ʃ/. A production-based account of the two sequences /sʃ/ and /ʃs/ in Catalan and other languages is proposed.

A study of jaw coarticulatory resistance and aggressiveness for Catalan consonants and vowels.

The goal of this study is to investigate coarticulatory resistance and aggressiveness for the jaw in Catalan consonants and vowels and, more specifically, for the alveolopalatal nasal //[symbol see text]/ and for dark /l/ for which there is little or no data on jaw position and coarticulation. Jaw movement data for symmetrical vowel-consonant-vowel sequences with the consonants /p, n, l, s, ∫, [ symbol see text], k/ and the vowels /i, a, u/ were recorded by three Catalan speakers with a midsagittal magnetometer. Data reveal that jaw height is greater for /s, ∫/ than for /p, [see text]/, which is greater than for /n, l, k/ during the consonant, and for /i, u/ than for /a/ during the vowel. Differences in coarticulatory variability among consonants and vowels are inversely related to differences in jaw height, i.e., fricatives and high vowels are most resistant, and /n, l, k/ and the low vowel are least resistant. Moreover, coarticulation resistant phonetic segments exert more prominent effects and, thus, are more aggressive than segments specified for a lower degree of coarticulatory resistance. Data are discussed in the light of the degree of articulatory constraint model of coarticulation.

Lingual kinematics and coarticulation for alveolopalatal and velar consonants in Catalan.

Vertical lingual movement data for the alveolopalatal consonants /ʃ/ and /ɲ/ and for the dorsovelar consonant /k/ in Catalan /aCa/ sequences produced by three speakers reveal that the tongue body travels a smaller distance at a slower speed and in a longer time during the lowering period extending from the consonant into the following vowel (CV) than during the rising period extending from the preceding vowel into the consonant (VC). For two speakers, two-phase trajectories characterized by two successive velocity peaks occur more frequently during the former period than during the latter, whether associated with tongue blade and dorsum (for alveolopalatals) or with the tongue dorsum articulator alone (for velars). Greater tongue dorsum involvement for /ɲ/ and /k/ than for /ʃ/ accounts for a different kinematic relationship between the four articulatory phases. The lingual gesture for alveolopalatals and, less so, that for velars may exert more prominent spatial and temporal effects on V2 than on V1 which is in agreement with the salience of the C-to-V carryover component associated with these consonants according to previous coarticulation studies. These kinematic and coarticulation data may be attributed to tongue dorsum biomechanics to a large extent.

The role of the spectral and temporal cues in consonantal vocalization and glide insertion.

This study investigates the perceptual role of several acoustic characteristics to glide generation processes affecting the consonants [t], [beta] and [eta], i.e., the vocalization of syllable-final [t] and syllable-initial [beta] into [w], and the insertion of [j] before syllable-final [eta]. Results from identification tests with synthetic speech stimuli performed on Catalan-speaking informants reveal that both the formant frequency characteristics (at the consonant steady-state period for [t] and [beta], and at the endpoint of the vowel transitions for [eta]), and the onset or onset/offset time of the vowel transitions may play an active role in vocalization and glide insertion. Mostly for the changes [t] > [w] and [eta]> [jeta], glide identification was triggered by formant frequency variations rather than by variations in the temporal implementation of the vowel transitions. The implications of the perception results for the interpretation of the sound changes of interest are evaluated.

Differences in base of articulation for consonants among Catalan dialects.

Electropalatographic data for several front lingual consonants, i.e., the dental /t/, the alveolars /n, l, s, r/ and the alveolopalatals /t∫, ∫, ʎ, ɲ/, show differences in constriction anteriority among Catalan dialects varying in the progression Valencian > Eastern, with the Majorcan dialect occupying an intermediate position. These differences do not conform to speaker- dependent differences in palate morphology and, to the extent that they operate on a varied range of consonants, may be attributed to base of articulation. Deviations from this pattern are associated with manner of articulation and symmetry demands. A specific dialect- dependent relationship between tongue dorsum contact and constriction fronting is interpreted assuming the existence of less laminal, more apical dental and alveolar stops, and less dorsal, more laminal alveolopalatals, in Valencian than in the other two dialects. These data are interpreted in terms of the articulatory characteristics for different tongue front settings which have been proposed in the literature.

An articulatory investigation of lingual coarticulatory resistance and aggressiveness for consonants and vowels in Catalan.

Lingual movement data for Catalan vowel-consonant-vowel sequences reveal differences in contextual coarticulatory variability in tongue position at the middle of the consonant for p>/n/>dark/l/>/s/>> and at vowel midpoint for /u/>/a/>/i/. The velar stop /k/ exhibits a high degree of contextual variability in the horizontal dimension but not in the vertical dimension. These differences in coarticulatory sensitivity are attributed to differences in articulatory constraint, e.g., palatality and frication cause a higher degree of resistance in the consonant than laterality. A higher degree of contextual variability for dark /l/ than expected appears to be associated with speaker-dependent differences in darkness degree. Contextual variability is greater at regions not involved in closure or constriction formation, e.g., at the tongue dorsum than at the tongue front for alveolars. Coarticulatory resistance and coarticulatory aggressiveness are positively correlated: Phonetic segments, which are especially resistant to coarticulatory effects from the adjacent segments, exert maximal coarticulation on them. Consequently, highly constrained segments such as alveolopalatal consonants turn out to affect tongue position for less constrained segments such as back vowels rather than vice versa.

Phonetic typology and positional allophones for alveolar rhotics in Catalan.

The present study reports electropalatographic and acoustic data on the positional and contextual characteristics of alveolar taps and trills in Majorcan, Valencian and Eastern Catalan. The two consonant classes are invariably opposed by degree of tongue dorsum contact and F2, but only differentiated by place of articulation when constriction location for the trill is sufficiently retracted. Trills are produced with less than three contacts and may exhibit a single contact in utterance-initial position and, less often, in /Cr, VrV/ sequences. Word-final and, to a lesser extent, preconsonantal rhotics are implemented as taps in Majorcan and Valencian, and strengthened into trills in Eastern Catalan. Moreover, there appears to be an inverse relationship between initial strengthening, and intervocalic weakening and the absence of syllable-final strengthening, for Valencian rhotics, which could be indicative of a pattern of intersegmental organization. Shortening and articulatory reduction turned out not to be necessarily related for extremely short Valencian taps, which undergo much undershoot intervocalically but are highly constricted in /C , rC/ sequences. Other research aspects such as devoicing and intergestural timing for Catalan alveolar rhotics are also investigated.

Darkness in [l] as a scalar phonetic property: implications for phonology and articulatory control.

Dorsopalatal contact and F2 data for speakers of dialectal groups with dark [1] (Majorcan Catalan, Eastern Catalan) and clear [l] (German, Catalan from the València region) provide some support for the hypothesis that degree of velarization or pharyngealization in the alveolar lateral consonant does not proceed categorically but gradually across dialects. Indeed, F2 frequency data for [l] in the context of [i] reveal that darkness does not distinguish the two dialectal groups but varies gradually from dialects with a very dark realization of [l] (Mallorqui) to those with a very clear realization (Valencià) through dialects exhibiting intermediate degrees of darkness (Eastern Catalan, German). A similar scenario applies to the [a] context. This finding questions the complex, two-gestural status of dark [l] and the notion that dark [l] should always be more coarticulation resistant than clear [l].

Underlying voicing in Majorcan Catalan word-final stop-liquid clusters.

This study investigates the extent to which phonetic voicing is maintained in word-final clusters composed of an underlying voiced stop followed by nonsyllabic /l/ or /r/ in Majorcan Catalan. Electropalatographic and acoustic data for five speakers of this Catalan dialect reveal that, in agreement with the non-syllabic status of the liquid, voicing for /l/ is only available if occurring during the preceding stop. The rhotic is always phonetically voiceless. Speakers differ regarding the extent to which they keep the underlying stop voicing distinction and the production strategies they use for that purpose. This distinction is highly robust and distributed over the entire syllable in nasal-stop-/l/ clusters for some speakers, but much 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 fold vibration, or else by closure duration rather than by voicing. It may be concluded that the word-final devoicing process operating in Catalan does not apply to Majorcan Catalan tautosyllabic stop clusters with a liquid, and that phonetic voicing may affect just the stop or both the stop and the liquid. The implications of these findings for sound change are discussed.

An EMA study of VCV coarticulatory direction.

This study addresses three issues that are relevant to coarticulation theory in speech production: whether the degree of articulatory constraint model (DAC model) accounts for patterns of the directionality of tongue dorsum coarticulatory influences; the extent to which those patterns in tongue dorsum coarticulatory direction are similar to those for the tongue tip; and whether speech motor control and phonemic planning use a fixed or a context-dependent temporal window. Tongue dorsum and tongue tip movement data on vowel-to-vowel coarticulation are reported for Catalan VCV sequences with vowels /i/, /a/, and /u/, and consonants /p/, /n/, dark /l/, /s/, /S/, alveolopalatal /n/ and /k/. Electromidsagittal articulometry recordings were carried out for three speakers using the Carstens articulograph. Trajectory data are presented for the vertical dimension for the tongue dorsum, and for the horizontal dimension for tongue dorsum and tip. In agreement with predictions of the DAC model, results show that directionality patterns of tongue dorsum coarticulation can be accounted for to a large extent based on the articulatory requirements on consonantal production. While dorsals exhibit analogous trends in coarticulatory direction for all articulators and articulatory dimensions, this is mostly so for the tongue dorsum and tip along the horizontal dimension in the case of lingual fricatives and apicolaminal consonants. This finding results from different articulatory strategies: while dorsal consonants are implemented through homogeneous tongue body activation, the tongue tip and tongue dorsum act more independently for more anterior consonantal productions. Discontinuous coarticulatory effects reported in the present investigation suggest that phonemic planning is adaptative rather than context independent.