Effects Of Consonantal Context Research Articles

Perceptuomotor compatibility effects in vowels: Effects of consonantal context and acoustic proximity of response and distractor.

In a cue-distractor task, speakers' response times (RTs) were found to speed up when they perceived a distractor syllable whose vowel was identical to the vowel in the syllable they were preparing to utter. At a more fine-grained level, subphonemic congruency between response and distractor-defined by higher number of shared phonological features or higher acoustic proximity-was also found to be predictive of RT modulations. Furthermore, the findings indicate that perception of vowel stimuli embedded in syllables gives rise to robust and more consistent perceptuomotor compatibility effects (compared to isolated vowels) across different response-distractor vowel pairs.

Effects of consonantal context on the learnability of vowel categories from infant-directed speech.

Recent studies have shown that vowels in infant-directed speech (IDS) are characterized by highly variable formant distributions. The current study investigates whether vowel variability is partially due to consonantal context, and explores whether consonantal context could support the learning of vowel categories from IDS. A computational model is presented which selects contexts based on frequency in the input and generalizes across contextual categories. Improved categorization performance was found on a vowel contrast in American-English IDS. The findings support a view in which the infant's learning mechanism is anchored in context, in order to cope with acoustic variability in the input.

Intelligibility of Sung Vowels: The Effect of Consonantal Context and the Onset of Voicing

Studies addressing the identification of sung vowels concern mainly the effect of the fundamental frequency (f0) and conclude that correct vowel identification decreases with increasing pitch. In one experiment, the impact of consonantal environment on the intelligibility of the vowels in high-pitched singing was also studied. The results of that experiment showed positive effect of the consonantal environment. This finding is in line with results that had been reported for speech in an earlier study. However, the data on singing are not as transparent as the authors suggest, and there are some conditions in the experiment that could also be controlled for more strictly. Therefore, the effect of the dynamic acoustic information encoded in the formant transitions at high fundamental frequencies is still an open question. The aim of the present study was to redesign and extend the above-mentioned experiment to test whether the phonetic context and the onset of the vowel uttered in isolation (namely the onset of voicing) have a positive effect on vowel identification. For this purpose, a vowel identification test was carried out. The stimuli included three Hungarian vowels /aː iː uː/ in three conditions (in /bVb/ context, in isolation and with eliminated onset) at seven different fundamental frequencies from 175 to 988 Hz (F3, B3, F4, B4, F5, B5, and speech). The stimuli were produced by one professional soprano singer. The results show that consonantal context does not specify vowel identity in singing as clearly as it has been demonstrated for spoken utterances. In addition, no effect of vowel onset (ie, the onset of voicing) was found. Recognition percentages seemed only to be dependent on f0 and vowel quality. The unexpected results lend themselves to two possible explanations: the reduction of the consonants and the undersampling of the formant transitions.

Temporal and spectral variability of vowels within and across languages with small vowel inventories: Russian, Japanese, and Spanish

Variability of vowels in three languages with small vowel inventories (Russian, Japanese, and Spanish) was explored. Three male speakers of each language produced vowels in two-syllable nonsense words (VCa) in isolation and three-syllable nonsense words (gaC1VC2a) embedded within carrier sentences in three contexts: bilabial stops in normal rate sentences and alveolar stops in both normal and rapid rate sentences. Dependent variables were syllable duration and formant frequency at syllable midpoint. Results showed very little variation across consonant and rate conditions in formants for /i/ in Russian and Japanese. Japanese short /u, o, a/ showed fronting (F2 increases) in alveolar context, which was more pronounced in rapid sentences. Fronting of Japanese long vowels was less pronounced. Japanese long/short vowel ratios varied with speaking style (isolation versus sentences) and speaking rate. All Russian vowels except /i/ were fronted in alveolar context, but showed little change in either spectrum or duration with speaking rate. Spanish showed a strong effect of consonantal context: front vowels were backed in bilabial context and back vowels were fronted in alveolar context, also more pronounced in rapid sentences. Results will be compared to female productions of the same languages, as well as American English production patterns.

The effect of consonantal context on intensity distribution in vowels

Overall vowel intensity varies intrinsically with vowel quality and in terms of immediate consonantal context. These variations affect the levels of formants F1–F4 and F0, which change in consonantal contexts according to a vowel−specific pattern [Jacewicz, J. Acoust. Soc. Am. 114, 2395 (2003)]. The current study further examines the differential distribution of acoustic energy across and within continuous frequency bands in the vowel as a function of vowel quality and consonantal context. The analysis technique used here was adopted from Sluijter and Van Heuven [J. Acoust. Soc. Am. 100, 2471−2485 (1996)], who measured differences in spectral intensity distribution across frequency bands as a function of stress. The intensity distribution of the vowels /i, i, ε, æ, u, u/ in American English were measured across eight frequency bands in a stressed [C1VC2] context (where C1=C2). Contexts were chosen which have the greatest (e.g., voiceless fricatives) and the smallest (e.g., voiced stops) effect on changes in relative amplitude of formant frequencies and F0 for each particular vowel. Preliminary results indicate that intensity variations across frequency bands as a function of consonantal context have a potential to change the overall spectral balance. [Work supported by NIDCD R03 DC005560−01.]

Discriminability and identification of English vowels by native Japanese speakers in different consonantal contexts

The purpose of the present experiment was to examine the effects of consonantal context on discrimination and identification of English vowels by native Japanese speakers learning English in Japan. A number of studies have assessed the effects of consonantal contexts on the perception of nonnative vowels. For instance, Strange et al. (1996, 2001) found that perceptual assimilation of nonnative vowels is affected by consonantal contexts, and Morrison (2002) has shown that Japanese speakers use durational cues to perceive English /i/–/I/. The present study revealed that consonantal context affects discriminability and identification of each English vowel differently. Of all the six vowel contrasts tested, /i/–/I/ was the most likely to be affected by voicing status of the surrounding consonants with it being easier to discriminate in voiceless consonantal contexts. Moreover, /I/ is more likely to be equated with the Japanese short vowel /i/ in a voiceless consonantal context which is in keeping with Morrison (2002). /æ/–/ɑ/, on the other hand, is the most strongly affected by the place of articulation of the preceding consonants. [Work supported by Grant-in-Aid for Scientific Research (C)(1)(1410635).]

Effects of consonantal context on perception of French rounded vowels by American English adults with and without French language experience

This study extended Gottfried’s [J. Phonetics 12, 91–114 (1984)] investigation of the effects of learning French on AE listeners categorial discrimination of the contrasts involving Parisian French vowels /y/, /o//, /u/, and /i/. Vowels were presented in /rabVp/ and /radVt/ bisyllables embedded in carrier phrases by three different speakers in an AXB discrimination task. Two groups were tested: proficient L2-French-speaking AE listeners (Exp) and non-French-speaking AE listeners (Inexp). Overall, the Exp group performed better than the Inexp group on /u-o//, /y-i/, and /y-o// distinctions (mean errors: Exp=5%, Inexp=24%). However, for /u-y/, the groups did not differ (Exp=30% vs Inexp=24% errors). The findings may be explained by perceptual assimilation patterns, which are determined, in part, by consonantal context. The Inexp group confused /y/ with /i/ in bilabial context, but /y/ with /u/ in alveolar context, whereas the Exp group confused /y/ with /u/, in both contexts. For all contrasts, the Inexp group performed better in bilabial than in alveolar context (16% vs 32% errors), whereas no context effect was revealed for the Exp group. The results suggest that learning a foreign language includes learning its coarticulatory rules.

Effects of consonantal context on perceptual assimilation of American English vowels by Japanese listeners.

This study investigated the extent to which adult Japanese listeners' perceived phonetic similarity of American English (AE) and Japanese (J) vowels varied with consonantal context. Four AE speakers produced multiple instances of the 11 AE vowels in six syllabic contexts /b-b, b-p, d-d, d-t, g-g, g-k/ embedded in a short carrier sentence. Twenty-four native speakers of Japanese were asked to categorize each vowel utterance as most similar to one of 18 Japanese categories [five one-mora vowels, five two-mora vowels, plus/ei, ou/ and one-mora and two-mora vowels in palatalized consonant CV syllables, C(j)a(a), C(j)u(u), C(j)o(o)]. They then rated the "category goodness" of the AE vowel to the selected Japanese category on a seven-point scale. None of the 11 AE vowels was assimilated unanimously to a single J response category in all context/speaker conditions; consistency in selecting a single response category ranged from 77% for /eI/ to only 32% for /ae/. Median ratings of category goodness for modal response categories were somewhat restricted overall, ranging from 5 to 3. Results indicated that temporal assimilation patterns (judged similarity to one-mora versus two-mora Japanese categories) differed as a function of the voicing of the final consonant, especially for the AE vowels, /see text/. Patterns of spectral assimilation (judged similarity to the five J vowel qualities) of /see text/ also varied systematically with consonantal context and speakers. On the basis of these results, it was predicted that relative difficulty in the identification and discrimination of AE vowels by Japanese speakers would vary significantly as a function of the contexts in which they were produced and presented.

Acoustic studies comparing Danish vowels, British English vowels, and Danish-accented British English vowels

Few studies have examined the production of English vowels by native speakers of languages with vowel inventories as large as, or larger than, English. Danish is such a language, whose vowels are unevenly distributed in the vowel space, with a densely populated upper portion and a sparsely populated lower portion of the vowel space. This paper reports on acoustic comparisons of British English vowels as produced by ten native speakers of British English and of Danish, and of Danish vowels as produced by ten native speakers of Danish. Danish and English vowels were produced in CVC syllables in a variety of consonantal contexts. Acoustic analyses revealed temporal, spectral, and dynamic differences between the vowels produced by the speaker groups. The results of this study suggest that comparisons of vowels across languages, as well as analyses of the productions of non-native speakers, are incomplete and may even be misleading unless the effects of consonantal context are taken into account. The results of this study also provide an interesting test case for Flege’s speech learning model, which makes predictions concerning the learnability of foreign language vowels based on their degree of difference from native language categories.

Aerodynamics of phonation: Effect of consonantal context on vowels.

Recordings of oral airflow have been made of four subjects producing VCV sequences with different middle consonants and an open vowel. The flow signals at vowel offset and onset have been inverse filtered using a software inverse filter and characterized as a function of time using measures of maximum flow, minimum flow, open quotient, and area of the glottal pulse. Results suggest that the aerodynamic properties of the source differ considerably among vowels following different consonants. For example, at the onset of a vowel following a voiceless stop or fricative, the source typically shows a breathy pattern of vibration, as evidenced by high values of peak flow and an open quotient close to 1; the source then changes gradually into a modal type of phonation. These variations can be explained by different observed patterns of coordination between the larynx and the oral articulators. The present study reports experimental data and simulations of such dynamic patterns of source variations using a two-mass model of the vocal folds incorporated into a low-frequency model of the vocal tract’s aerodynamics. [Work supported by NIH.]

Effect of levels of stimulus uncertainty and consonantal context on formant frequency discrimination.

Discrimination thresholds for the second formant of vowels in consonantal context were significantly larger than for vowels in isolation in a report by Mermelstein [J. Acoust. Soc. Am. 63, 572 (1978)]. These results were not upheld in a recent report to this society [Kewley-Port and Watson, J. Acoust. Soc. Am. 89, 1996 (A) (1991)] for testing under minimal stimulus uncertainty procedures. Moreover, Mermelstein’s thresholds were a factor of 5 larger than those reported by Kewley-Port and Watson. The present experiment examines the effects of testing under higher levels of stimulus uncertainty in conditions more similar to those of Mermelstein. For well-trained subjects, most thresholds for the eight CVC stimuli tested did not change when levels changed from minimal to medium uncertainty. Further studies, using testing conditions similar to those of Mermelstein, employed untrained subjects. Results indicated that some subjects rapidly improved their ability to discriminate changes in formant frequency during just 1 h of testing. The differential effects of consonantal context, training, and levels of stimulus uncertainty will be discussed. [Research supported by NIH and AFOSR.]

Static, dynamic, and relational properties in vowel perception

The present work reviews theories and empirical findings, including results from two new experiments, that bear on the perception of English vowels, with an emphasis on the comparison of data analytic "machine recognition" approaches with results from speech perception experiments. Two major sources of variability (viz., speaker differences and consonantal context effects) are addressed from the classical perspective of overlap between vowel categories in F1 x F2 space. Various approaches to the reduction of this overlap are evaluated. Two types of speaker normalization are considered. "Intrinsic" methods based on relationships among the steady-state properties (F0, F1, F2, and F3) within individual vowel tokens are contrasted with "extrinsic" methods, involving the relationships among the formant frequencies of the entire vowel system of a single speaker. Evidence from a new experiment supports Ainsworth's (1975) conclusion [W. Ainsworth, Auditory Analysis and Perception of Speech (Academic, London, 1975)] that both types of information have a role to play in perception. The effects of consonantal context on formant overlap are also considered. A new experiment is presented that extends Lindblom and Studdert-Kennedy's finding [B. Lindblom and M. Studdert-Kennedy, J. Acoust. Soc. Am. 43, 840-843 (1967)] of perceptual effects of consonantal context on vowel perception to /dVd/ and /bVb/ contexts. Finally, the role of vowel-inherent dynamic properties, including duration and diphthongization, is briefly reviewed. All of the above factors are shown to have reliable influences on vowel perception, although the relative weight of such effects and the circumstances that alter these weights remain far from clear. It is suggested that the design of more complex perceptual experiments, together with the development of quantitative pattern recognition models of human vowel perception, will be necessary to resolve these issues.

Effects of consonantal context on vowel lipreading.

The effects of consonantal context on vowel lipreading were assessed for 30 adults with mild-to-moderate sensorineural hearing loss who lipread videotape recordings of two female talkers. The stimuli were the vowels /i,I,alpha,U,u/ in symmetric CVC form with the consonants /p,b,f,v,t,d,f,g/ and in the asymmetric consonantal contexts /h/-V-/g/, /w/-V-/g/, /r/-V-/g/. Analyses of the confusion matrices from each talker indicated that vowel intelligibility was significantly poorer in most contexts involving highly visible consonants, although the utterances of one talker were highly intelligible in the bilabial context. Among the visible contexts, the fricative and labiodental contexts in particular produced the lowest vowel intelligibility regardless of talker. Lax vowels were consistently more difficult to perceive than tense vowels. Implications for talker selection and refinement of the concept of viseme were drawn.

Identification of French vowels

Studies of the identification of American English vowels have found that vowels are better identified in consonantal context than in isolation [W. Strange, R. R. Verbrugge, D. P. Shankweiler, and T. R. Edman, J. Acoust. Soc. Am. 60, 213–24 (1976)]. This effect of consonantal context has been attributed to dynamic acoustic information in formant transitions. It has also been hypothesized that phonological factors allow syllable-medial vowels to be better identified. In particular, lax vowels are linguistically inappropriate in isolation, therefore identification of them should be poorer in that context. Since phonological factors are language-specific, one might approach the problem by looking at a language whose phonological system is different from English. French is a language where one vowel/e/that is appropriate in syllable-final position is not appropriate medially. This is a phonological constraint that is the converse of English. Four native speakers of French produced the 11 stressed, oral vowels of French. Comparision was made of the identification of the vowels by native French and American subjects. Influences of phonological and acoustic factors are discussed. [Supported by NIMH, NICHD.]

Consonantal Context and Vowel Perception in Normal and Clipped Speech

An experiment was done to study the effect of consonantal context on vowel perception in normal and infinitely clipped speech. In this experiment, 10 Hindi vowels | i, e, ∈, a, Λ, ɔ, o, U, u | were placed in | hΛj—J | and |hΛw—w| contexts, and recorded by two male speakers on a tape. The recordings were presented to six well-trained listeners with or without infinite peak clipping. Listeners' responses were summarized in a confusion matrix for each context and for each condition of testing. Thus, four confusion matrices were formed. Study of the confusion matrices reveals that the consonantal context does affect the perception of vowels in some of its aspects. Vowel intelligibility was found to be very different between the two contexts, while the relative intelligibility of vowels and specific confusions among vowels were not found to be significantly different.