Intrinsic Vowel Duration Research Articles

Developmental Aspects of Greek Vowel Reduction in Different Prosodic Positions

This study investigates the development of Greek vowel reduction across different prosodic positions (stressed, pre-stressed, post-stressed), examining normative data from 72 participants aged 3 years to adulthood and balanced for gender. Participants performed a delayed repetition task, producing real trisyllabic words with the vowels [i, ε, ɐ, o, u] examined in the second syllable. Measurements included relative vowel duration, normalized acoustic vowel space areas, and Euclidean distances of vowels from the centroid of the acoustic space. Our findings show that changes in speech motor control, system stiffness, and stress marking with age, along with children’s prosody sensitivity, contributed to several developmental milestones: the completion of the developmental trajectory of relative vowel duration and temporal vowel reduction at early adolescence; the attainment of adult-like spatial vowel characteristics and their reduction at preschool age; and the early acquisition of the prosodic strength of the stress conditions, leading to vowel reduction from the stressed to pre-stressed to post-stressed conditions. The correlation strength between temporal and spatial vowel reduction across ages revealed age-related differences in spatiotemporal speech organization, with significant gender-related differences observed only in vowel space areas, where females exhibited larger areas possibly related to sociophonetic factors. Intrinsic vowel duration appeared from age 3.

Effects of Word Stress on Vowel Duration and Vowel Quality in the Speech of Korean Learners of English

Unstressed English vowels are reduced in their durational and spectral aspects. Vowel reduction in relation to word stress in English has been one of the challenges faced by Korean learners of English in learning English vowel system. In this study, we investigated effects of word stress on the vowel duration and vowel quality. This study focused on two unstressed vowels (/ə/ and /ɪ/) and three stressed vowels (/ʌ/, /ɪ/, and /i/). Words with five target vowels in the first syllable of word were collected from sentences produced by two subject groups. Vowel durations and first and second formant values were calculated and analyzed for the effect of stress which interplayed with intrinsic vowel duration and vowel quality. Study results indicated that speech data of Korean learners of English had much less magnitude in vowel shortening and reduction of vowel quality in unstressed vowels than those of English speakers. In addition, the five target vowels tended to be grouped into two in vowel space for Korean learners of English. Pedagogical implications of this study are discussed to improve learning and teaching English vowel system for Korean learners of English.

Toward an individual-difference perspective on phonologization

Phonologization is often understood to be a process along the pathway of sound change where low-level physiological or perceptual variation that gives rise to sound patterns is explicitly encoded in the grammar. The nature of this transition and how it comes about remain largely unclear. The broad theoretical goal of this paper is to argue that phonologization should be defined at the level of the individual; it takes place whenever an individual acquires a so-called “phonetic precursor” as an intended, and controlled, pattern in the language, even if the pattern exhibits gradient properties. To illustrate this perspective, a case study on the nature of individual variation in vowel duration as a function of vowel height in Cantonese is presented, offering evidence that some Cantonese speakers have phonologized the height-dependent vowel duration effect and discussing the implications of this result for understanding intrinsic vowel duration as a phonetic precursor to sound change. The article closes with a discussion regarding the current proposal in relation to past models of phonologization and offers suggestions for future directions in phonologization research.

Vowel-Specific Intelligibility and Acoustic Patterns in Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis.

Purpose The purpose of the study was to investigate vowel-specific intelligibility and acoustic patterns of individuals with different severities of dysarthria secondary to amyotrophic lateral sclerosis (ALS). Method Twenty-three individuals with dysarthria secondary to ALS and 22 typically aging individuals participated as speakers. Participants with ALS were divided into 2 severity groups (severe, mild). For vowel-specific intelligibility data, 135 listeners participated in the study. Vowel-specific intelligibility, intrinsic vowel duration, 1st and 2nd formants (F1 and F2), vowel inherent spectral change (VISC), and absolute VISC were examined. Results A significant interaction between severity group and the vowel-specific intelligibility pattern as well as F1, F2 VISC, and absolute F2 VISC was observed. Specifically, individuals with severe dysarthria showed a significantly less intelligible /ɪ/ than /ɛ/, unlike individuals with mild dysarthria and typically aging individuals. In addition, vowel intelligibility of /ɪ/ showed the strongest association to the severity measures in individuals with ALS. A number of vowel-specific findings are reported in the acoustic variables. Acoustic correlates of vowel-specific intelligibility were identified. Conclusion Vowel-specific intelligibility patterns are different across severity groups; particularly, low intelligibility of /ɪ/ was noted in individuals with severe dysarthria. Individuals with dysarthria maintained the acoustic contrast in duration and F1 VISC among vowels but did not maintain the other spectral contrasts. Reduction of acoustic vowel space was observed primarily due to high F1 in high vowels in individuals with severe dysarthria. Regression findings suggest that the high F1 values of high and mid vowels and F2 reduction of high- and mid-front vowels decreased vowel-specific intelligibility. In addition, vowel duration influenced the vowel intelligibility of vowels that required short intrinsic vowel duration. Lastly, F2 VISC influenced the vowel intelligibility of /ɪ/. Overall, the vowel-specific intelligibility pattern is related to both vowel-specific characteristics and group-specific articulatory control dysfunction.

Word-level prosodic measures and the differential diagnosis of apraxia of speech

ABSTRACTImpaired production of prosody is considered a primary diagnostic criterion for apraxia of speech. In this study, we examined diagnostic relevance for five word-level prosody measures. Seven speakers with AOS, nine with aphasia and no AOS, and 19 age-matched neurotypical controls produced nine words consisting of three or four syllables. Lexical stress indices were computed based on relative values for duration, fundamental frequency, and intensity across pairs of unstressed-stressed syllables with varying intrinsic vowel duration contrast patterns. A simple average syllable duration measure was also obtained. AOS speakers differed from the other two groups on three metrics that were solely or primarily derived from duration measures. The degree of diagnostic overlap was smallest for the syllable duration metric, which also showed the strongest inter-observer reliability and most complete overlap between neurotypical speakers and speakers with aphasia and no AOS. Vowel intrinsic durational properties affected lexical stress metrics significantly, indicating a need to select word targets purposefully. Based on these results, it appears that the average syllable duration metric is a more stable and informative alternative for differential diagnostic purposes. The results will, however, need to be replicated in a larger sample.

Durational Interaction of Stops and Vowels in English and Korean Child-Directed Speech

The current study observes the durational interaction of tautosyllabic consonants and vowels in the word-initial position of English and Korean child-directed speech (CDS). The effect of phonological laryngeal contrasts in stops on the following vowel duration, and the effect of the intrinsic vowel duration on the release duration of preceding stops in addition to the acoustic realization of the contrastive segments are explored in different prosodic contexts - phrase-initial/medial, focal accented/non-focused - in a marked speech style of CDS. A trade-off relationship between Voice Onset Time (VOT), as consonant release duration, and voicing phonation time, as vowel duration, reported from adult-to-adult speech, and patterns of durational variability are investigated in CDS of two languages with different linguistic rhythms, under systematically controlled prosodic contexts. Speech data were collected from four native English mothers and four native Korean mothers who were talking to their one-word staged infants. In addition to the acoustic measurements, the transformed delta measure is employed as a variability index of individual tokens. Results confirm the durational correlation between prevocalic consonants and following vowels. The interaction is revealed in a compensatory pattern such as longer VOTs followed by shorter vowel durations in both languages. An asymmetry is found in CV interaction in that the effect of consonant on vowel duration is greater than the VOT differences induced by the vowel. Prosodic effects are found such that the acoustic difference is enhanced between the contrastive segments under focal accent, supporting the paradigmatic strengthening effect. Positional variation, however, does not show any systematic effects on the variations of the measured acoustic quantities. Overall vowel duration and syllable duration are longer in English tokens but involve less variability across the prosodic variations. The constancy of syllable duration, therefore, is not found to be more strongly sustained in Korean CDS. The stylistic variation is discussed in relation to the listener under linguistic development in CDS.

Temporal structure in the speech of persons with dementia: A preliminary study.

Although cognitive and language processes in dementia have been studied extensively, the question of motor speech degeneration in the course of dementing illness is a relatively unexplored area. The potential for early dissociation of motor functions of language at the level of speech production has not been explored; an interaction between motor speech and language production and perception changes should inform our understanding of the deterioration in dementia. If early motor declines are found, they may provide an additional early marker and contribute to early detection, giving further insight to the character of neurological deterioration in this disease. This study explores the temporal structure of speech in individuals in the mild-to-moderate stages of the disease. In this preliminary study, participants were asked to produce a series of four-word phrases containing target word in phrase-medial or phrase final position. The target words contained the vowel in “heed,” “head,” or “had,” and began with a fricative or voiced or voiceless stop consonant and ended with either /t/ or /d/. Thus, we are able to examine four aspects of the temporal patterns of speech in these persons: intrinsic vowel duration, VOT, phrase-final lengthening, and the effect of final consonant voicing on vowel duration.

Stress and tone in East Slavic dialects

The East Slavic languages have distinctive stress and no contrastive vowel length; the phonetic correlates of word stress are increased vowel duration, intensity and changes in vowel quality. But there are East Slavic dialects with an unusual type of word prosody: word stress is distinctive, yet the immediately pretonic vowel is as long as or longer than the vowel under stress, and there is a fixed tonal contour over the two syllables. I argue that the additional duration in the pretonic syllable is due to a type of stress-to-tone mapping in which a lexical high tone is assigned to the pretonic syllable. Variation across these and other closely related dialects reveals a typology of stress and tone mapping with increasing dependence on intrinsic vowel duration and sonority. The additional vowel length on neutralised/reduced vowels in the immediately pretonic position in some dialects raises questions about the relationship of vowel duration and vowel reduction in East Slavic. The prosody of these East Slavic dialects appears to be typologically unusual in having both lexical stress and non-contrastive tone, and in specifically not aligning high tone with stress.

Formant movement and duration cues in the identification of vowels

Traditionally, target values of F1 and F2 are viewed as primary determinants of vowel identity. Several recent studies, however, have demonstrated the importance of dynamic formant information to vowel identification. The present study examines the contribution of both dynamic and durational information to vowel identification using sine-wave vowel analogs. Sine-wave stimuli consisting of two tones representing F1 and F2 were constructed using careful LPC measurements of ten vowels produced in /dVd/ context by male and female speakers. Four types of stimuli were constructed by varying two factors: (1) appropriate versus fixed vowel duration and (2) variation in tones representing formant movement throughout the token versus static target formant values. Listeners identified the sine-wave vowel analogs using a key-word response form. Results demonstrated that stimuli with appropriate vowel duration were identified with significantly greater accuracy than those with fixed length. For appropriate duration stimuli, there was no significant difference for dynamic versus static tokens. However, for fixed length stimuli listeners identified dynamic tokens with significantly greater accuracy than static stimuli. This suggests that intrinsic vowel duration, as expected, is an important cue to vowel identity and that dynamic formant information is used more by listeners when duration cues are unavailable.

On explaining intrinsic vowel duration differences: An electromagnetic midsagittal articulometer (EMMA) study

The purpose of this study is to determine whether intrinsic vowel duration differences arise from an explicit timing control strategy or solely from the distance an articulator travels. Presumably, a difference in control strategy would be reflected in a change in the relation of peak velocity to distance traveled, or in the amount of time position is maintained. An EMMA system was used to track movements of points on the tongue and jaw during the production of /dVs/ (V=/e, E, æ, a, inverted vee/) tokens in a constant frame at two different speaking rates. Measurements were made of target position, distance traveled, and peak velocity for each gesture toward and away from the vowel target. Preliminary results from one speaker suggest that the duration of articulatory movement can be well predicted by articulatory distance and peak velocity alone. Furthermore, all of the unreduced vowels measured in the study showed a similar relationship between peak velocity and displacement, suggesting that the same control strategy was used for all of them. [Work supported by NIH.]

Effects of rate and bite-block manipulations on relationships between duration and variability in children’s and adults’ speech.

Based on the assumption that speakers are less skilled at talking under atypical conditions, segment duration and variability were studied in 5 and 11 yr olds and a group of adults as they produced short phrases in normal, fast-rate, and bite-block conditions. Preliminary analyses indicate that for all three groups, the bite-block task generally did not cause much difference in duration or variability from the normal condition. Although duration and variability both decreased in the fast-rate condition for all groups, relative changes in variability were typically less than those for duration. Several other comparisons of duration and variability also did not show very strong relationships between these two measures. For instance, variability was also evaluated as a function of intrinsic vowel duration. Although high vowels were approximately 30% shorter than low vowels for the three groups, variability was only about 15% less for high than for low vowels. For individual subjects, correlations between duration and variability were also generally rather low. Implications for speech production development will be discussed.

Context‐independent dynamic information for vowel identification

Previous studies have demonstrated that listeners can identify vowels spoken rapidly in stop consonant‐vowel‐stop consonant syllables even when vocalic nuclei of the acoustic signals are attenuated to silence, leaving only initial and final transitions. In this study, mixed consonant “silent‐center” (MC) conditions were generated in which the initial and final transitions of syllables containing the same vowel but different stop consonants were interchanged, thus altering context‐dependent formant trajectories. In one condition, silent intervals were appropriate for the original vowel and the final consonant; in a neutral duration MC condition, silent intervals were adjusted so that intrinsic vowel duration cues were eliminated. Identification errors in the MC condition (8%) were not significantly higher than for original silent‐center syllables; the neutral duration MC condition produced somewhat more errors (15%), but identification was more accurate than for initial transitions (35% errors) or final transitions (52% errors) presented alone. These results suggest that some perceptually relevant aspects of dynamic information are context independent. Representations of formant trajectories presented in F1‐F0/F3‐F2 “space” demonstrate context‐dependent and ‐independent aspects of dynamic information. [Work supported by NINCDS.]

Effects of bite block speech on intrinsic segment duration.

The fact that low vowels tend to have longer intrinsic duration than high vowels is sometimes attributed to mechanical characteristics associated with the greater distance the jaw travels in producing low vowels. To investigate this tendency, 6 adult speakers of English each produced 72 [h]-vowel-consonant stimuli containing high and low vowels under 'normal' conditions and with their jaw fixed. If duration differences commonly observed between high and low vowels are a result of only mechanical effects of mandibular movement, it was hypothesized that stabilizing the jaw would eliminate these intrinsic vowel duration differences. Based on acoustic measurements that were made, it was found that the fixed-jaw conditions affected the intrinsic durational differences between high and low vowels to some extent, but the contrast was not entirely removed. In addition to the vowel duration changes, a number of systematic effects upon consonant closure duration were also observed as a result of the normal versus fixed-jaw conditions.

Acoustic and articulatory evidence for consonant-vowel interactions

Previous acoustical research [e.g., C. Fowler, Phonetica 38, 35–50 (1981)] has suggested that consonants and vowels are not produced strictly sequentially but rather overlap in time. By this account, the degree of co-production of underlying segments affects the pattern of the resulting acoustical durations. In the present experiment, two subjects produced utterances of the form CVC(C), where the vowels were either /ε/ or /æ/ and the following consonants were /p/, /k/, /s/, /ps/, /ks/, /sp/, or /sk/, Movements of the lips and jaw were monitored with a Selspot system. Laryngeal movements were measured by means of transillumination, and the accompanying acoustic signal was recorded. Analysis of the acoustic durations revealed that vowel duration was shorter when followed by a cluster than by a singleton in both vowel contexts. However, the following consonant durations were longer for the vowel /ε/ than for /æ/. Analyses of the lip and jaw kinematics suggested that the vowel shortening in the cluster contexts was produced in part by greater temporal overlap of the underlying segments. The influence of the intrinsic vowel duration on the following consonants may reflect a syllabic constraint on articulatory timing. The results will be discussed in terms of the articulatory structure of phonetic segments and the sequential coordination of consonant and vowel gestures. [Work supported by NINCDS.]

Prediction of phoneme duration by a distinctive feature matrix

For the analysis and synthesis of intonation, we tried to find a simple method of estimating intrinsic segmental duration. Multiple linear regression analysis was carried out using phoneme durations as the dependent variable with several types of independent variables: formants, a numerically coded vowel chart, and a binary coded distinctive feature matrix. We found that the distinctive feature matrix was suitable not only to estimate intrinsic vowel duration, but also intrinsic consonant duration. Our demonstration is restricted to English in this article.

Context‐induced vowel duration change and intrinsic vowel duration

This study investigated the pattern of duration change of vowels of different quality (and intrinsic duration) when spoken in contexts which differently affect duration. Stressed vowel duration was measured in five contexts; test stimuli included all 15 English vowels and diphthongs. Duration change induced by context appeared to be independent of intrinsic vowel duration and vowel quality, and was best described as a constant which combines additively with some measure of intrinsic vowel duration. Results of other studies which examined similar data are discussed.

Acoustic investigation of intrinsic vowel duration in Danish

The duration of twelve short and long stressed vowels in disyllabic nonsense words, embedded in a carrier sentence, recorded 10 times by each of five speakers, was measured. The vowels can be grouped (roughly) in five tongue height categories, and duration was found to increase significantly from category 1 (highest) through 5 (lowest), in about 1 cs steps. Unstressed vowels show the same tendency but the increase in duration with lower tongue height is considerably smaller. Variation in speaking rate (even rather considerable) did not significantly influence the relationship between high and low vowels. In contradistinction to earlier investigations, it seems that the difference in duration between long and short vowels is constant over different tongue heights, i.e. Vshort = Vlong – b, where b is a constant (approximately 5 cs).

Intrinsic vowel duration and formant frequencies: Data from speech acquisition

The vowels of American English are specified by particular formant frequency patterns and durations. Acoustic data derived from the speech of children between the ages of 69 and 145 weeks show that the vowels that they produce in meaningful words often have mismatched formant frequency patterns and durations. The formant frequency pattern of an intended [i], for example, may have the duration of an [1]. Psychoacoustic experiments using computer edited stimuli derived from the children's vowel productions demonstrate the interaction of formant frequency patterns and duration as acoustic cues to vowel perception. Intrinsic vowel duration and control of the supralaryngeal vocal tract appear to be independent parameters in the acquisition of speech. Hypothetical phonetic features like Tenseness thus can not be causally linked to relative vowel duration.