Acoustic Vowel Space Research Articles

Relationship between tongue positions and formant frequencies in female speakers

This study examined the relationship (1) between acoustic vowel space and the corresponding tongue kinematic vowel space and (2) between formant frequencies (F1 and F2) and tongue x-y coordinates for the same time sampling point. Thirteen healthy female adults participated in this study. Electromagnetic articulography and synchronized acoustic recordings were utilized to obtain vowel acoustic and tongue kinematic data across ten speech tasks. Intra-speaker analyses showed that for 10 of the 13 speakers the acoustic vowel space was moderately to highly correlated with tongue kinematic vowel space; much weaker correlations were obtained for inter-speaker analyses. Correlations of individual formants with tongue positions showed that F1 varied strongly with tongue position variations in the y dimension, whereas F2 was correlated in equal magnitude with variations in the x and y positions. For within-speaker analyses, the size of the acoustic vowel space is likely to provide a reasonable inference of size of the tongue working space for most speakers; unfortunately there is no a priori, obvious way to identify the speakers for whom the covariation is not significant. A second conclusion is that F1 variations reflect tongue height, but F2 is a much more complex reflection of tongue variation in both dimensions.

An acoustic description of spectral and temporal characteristics of Azerbaijani vowels

AbstractThis paper presents an acoustic description of the nine Azerbaijani vowels; investigating the underlying acoustic and temporal characteristics of its vowel system. We explored acoustic and temporal parameters including: the first three formants (F1, F2 and F3), fundamental frequency (F0) and duration of the vowels. Participants in this study were 20 male and 23 female Azerbaijani speakers with a Tabrizi dialect. They were asked to utter three repetitions of the nine Azerbaijani vowels in three natural word contexts, embedded in carrier sentences. Results showed that the [ɯ] and [œ] vowels had a large overlap in the F1–F2 vowel space. Further analysis suggested that F3 is an important cue in discrimination of this vowel pair. Vowel-intrinsic duration effect seemed to be relatively strong in Azerbaijani. Other universal features also were found in the production of Azerbaijani vowels: low vowels and female speakers had lower F0 values. Surprisingly, in contrast with previous results for most languages, the average duration of Azerbaijani vowels was greater in males than females. The results of this study define the acoustic vowel-space of the Azerbaijani language and develop a database for further comparisons and investigations.

Acoustic properties of vowel production in prelingually deafened Mandarin-speaking children with cochlear implants.

The present study examined the acoustic features of vowel production in Mandarin-speaking children with cochlear implants (CIs). The subjects included 14 native Mandarin-speaking, prelingually deafened children with CIs (2.9-8.3 yr old) and 60 age-matched, normal-hearing (NH) children (3.1-9.0 years old). Each subject produced a list of monosyllables containing seven Mandarin vowels: [i, a, u, y, ɤ, ʅ, ɿ]. Midpoint F1 and F2 of each vowel token were extracted and normalized to eliminate the effects of different vocal tract sizes. Results showed that the CI children produced significantly longer vowels and less compact vowel categories than the NH children did. The CI children's acoustic vowel space was reduced due to a retracted production of the vowel [i]. The vowel space area showed a strong negative correlation with age at implantation (r = -0.80). The analysis of acoustic distance showed that the CI children produced corner vowels [a, u] similarly to the NH children, but other vowels (e.g., [ʅ, ɿ]) differently from the NH children, which suggests that CI children generally follow a similar developmental path of vowel acquisition as NH children. These findings highlight the importance of early implantation and have implications in clinical aural habilitation in young children with CIs.

Tongue movement pattern in speakers with dysarthria in production of “Ohio”

A different range of tongue motion during speech production has been assumed in speakers with dysarthria across different severity groups based on the previous findings in acoustic vowel space. To further confirm these findings, this study examined the tongue movement pattern in speakers with dysarthria during the production of “Ohio,” a target word that requires the consecutive production of multiple vowels. Ten speakers with dysarthria of varying severity participated in this study. Three dimensional electromagnetic articulography (Wave system) was utilized to identify tongue movement trajectory during the target word production. Each speaker produced three repetitions of the word “Ohio” in the carrier phrase “I say a__ again.” X, y, and z coordinate values from the tongue sensor (positioned approximately 25 mm from the tongue apex) were recorded. Statistical analyses showed that speakers with severe dysarthria produced a) less overall tongue movement, b) slower speed, c) less absolute tongue advancement-retraction and tongue height movement, and d) greater distance between starting /o/ and ending /o/ positions than speakers with mild dysarthria. Results are discussed with regard to the interpretation of tongue movement displacement and trajectory shape difference in speakers with dysarthria across different severity groups.

Vowel Classification and Vowel Space in Persian

This article aims to develop an acoustic vowel space in Persian speech. There are several aspects in this survey which make it different from what has been done before. The first is related to the issue of speech material. The need for more natural choice in voice qualities in recent years exhort us not relying on citation form or artificial sound produced in laboratories. Furthermore, the formant frequencies were not extracted from specified vowels, in specified context. In contrast, we are interested in the shape of vowel space determined by extremely large collections of vowel tokens, with whatever distribution of categories and context they may have in the read text. Thirdly, the vowels selected in the database for calculation of the area of vowel space are being stratified for locating in stressed or unstressed syllables, or being uttered by male or female speakers. So, we are simultaneously dealing with four groups. But the most important aspect is related to the methodology used for better plotting of vowels. Either F1*F2 or F1 *F2-F1 is leaded to better vowel classification is a matter being evaluated by two parameters: (a) linear discriminant analysis and (b) scatter reduction.

Impact of the LSVT on vowel articulation and coarticulation in Parkinson’s disease

The purpose of this study was to investigate the impact of the Lee Silverman Voice Treatment (LSVT®) on vowel articulation and consonant–vowel (C–V) coarticulation in dysarthric speakers with Parkinson’s disease (PD). Nine Quebec French speakers diagnosed with idiopathic PD underwent the LSVT®. Speech characteristics were compared before and after treatment. Vowel articulation was measured using acoustic vowel space and calculated with the first (F1) and second formant (F2) of the vowels /i/, /u/ and /a/. C–V coarticulation was measured using locus equations, an acoustic metric based on the F2 transitions within vowels in relation to the preceding consonant. The relationship between these variables, speech loudness and vowel duration was also analysed. Results showed that vowel contrast increased in F1/F2 acoustic space after administration of the LSVT®. This improvement was associated with the gain in speech loudness and longer vowel duration. C–V coarticulation patterns between consonant contexts showed greater distinctiveness after the treatment. This improvement was associated with the gain in speech loudness only. These results support the conclusions of previous studies investigating the relationship between the LSVT®, speech loudness and articulation in PD. These results expand clinical understanding of the treatment and indicate that loud speech changes C–V coarticulation patterns. Clinical applications and theoretical considerations are discussed.

Vietnamese Vowels Produced by Australian Vietnamese Speakers

This paper reported a study that acoustically examined the vowel features of Vietnamese language used by the Vietnamese community in Australia. Vowels produced by older (n=10) and younger (n=10) Vietnamese Australians residing in Brisbane, Australia, were acoustically examined and compared with those produced by corresponding older (n=10) and younger (n=10) Vietnamese residing in Ho Chi Minh/Can Tho City, Vietnam. The results showed that (i) almost all vowel tokens produced by the four groups of speakers were acoustically significantly different in vowel space; (ii) the Younger Vietnamese Australian residents’ tokens of vowels which look similar in conventional Vietnamese orthography tended to cluster with each other; (iii) the vowel productions of the Younger Vietnamese residents in Australia tended to occupy higher and/or more front regions than those of the Younger Vietnamese residents in Vietnamese group in terms of the acoustic vowel space; and (iv) the vowel tokens produced by the Older Vietnamese residents in Australia and Older Vietnamese residents in Vietnam groups occupied different regions in the acoustic vowel space.

Articulatory Changes in Vowel Production following STN DBS and Levodopa Intake in Parkinson's Disease.

Purpose. To investigate the impact of deep brain stimulation of the subthalamic nucleus (STN DBS) and levodopa intake on vowel articulation in dysarthric speakers with Parkinson's disease (PD). Methods. Vowel articulation was assessed in seven Quebec French speakers diagnosed with idiopathic PD who underwent STN DBS. Assessments were conducted on- and off-medication, first prior to surgery and then 1 year later. All recordings were made on-stimulation. Vowel articulation was measured using acoustic vowel space and formant centralization ratio. Results. Compared to the period before surgery, vowel articulation was reduced after surgery when patients were off-medication, while it was better on-medication. The impact of levodopa intake on vowel articulation changed with STN DBS: before surgery, levodopa impaired articulation, while it no longer had a negative effect after surgery. Conclusions. These results indicate that while STN DBS could lead to a direct deterioration in articulation, it may indirectly improve it by reducing the levodopa dose required to manage motor symptoms. These findings suggest that, with respect to speech production, STN DBS and levodopa intake cannot be investigated separately because the two are intrinsically linked. Along with motor symptoms, speech production should be considered when optimizing therapeutic management of patients with PD.

Formant frequency characteristics in Palestinian Arabic-speaking aphasics

The aim of this paper is to examine the acoustic characteristics of Arabic vowels as produced by Palestinian Arabic-speaking Broca’s aphasics compared to normal speakers. Five subjects diagnosed with Broca’s aphasia and five normal speakers residing in the West Bank participated in this study. The subjects produced 240 vowel tokens of the eight Arabic vowels (/i:/, /i/, /e:/, /a:/, /a/, /o:/, /u:/ and /u/,). The samples were analyzed using PRAAT and the formants F1 and F2 of the eight Arabic vowels were measured. F1 and F2 values were compared to the data in the literature. Comparisons among speakers of Palestinian Arabic indicated that Broca’s aphasics’ formant frequencies were significantly different to those of normal speakers, showing that formant frequencies of F1 and F2 are generally higher among Broca’s aphasics compared to the control group. Furthermore, the findings reveal that the acoustic vowel space of Broca’s aphasics is more centralized compared to the control subjects. The results also indicate that Broca’s aphasics were able to maintain the phonemic contrast between the long and short vowels. In general, the results may contribute to neurolinguistic research across different languages, especially given that Palestinian Arabic is studied significantly less than other Arabic dialects. Furthermore, the results may have clinical applications when evaluating and/or treating Palestinian Arabic-speaking Broca’s aphasics.

A study of tongue trajectories for English /æ/ using articulatory signals automatically extracted from lingual ultrasound video

While ultrasound imaging has made articulatory phonetics more accessible, quantitative analysis of ultrasound data often reduces speech sounds to tongue contours traced from single video frames, disregarding the temporal aspect of speech. We propose a tracing-free method for directly converting entire ultrasound videos to phonetically interpretable articulatory signals using Principal Component Analysis of image data (Hueber et al. 2007). Once a batch of ultrasound images (e.g., 36,000 frames from 10 min at 60 fps) has been reduced to 20 principal components, numerous techniques are available for deriving temporally changing articulatory signals that are both phonetically meaningful and comparable across speakers. Here we apply a regression model to find the linear combination of PCs that is the lingual articulatory analog of the front diagonal of the acoustic vowel space (Z2-Z1). We demonstrate this technique with a study of /æ/ tensing in 20 speakers of North American English varieties with different tensing environments (Labov 2005). Our results show that /m n/ condition a tongue raising gesture that is aligned to the vowel nucleus, while /ɡ/ conditions anticipatory raising toward the velar target. /ŋ/ patterns consistently with the other velar rather than the other nasals.

Articulatory–acoustic vowel space: Application to clear speech in individuals with Parkinson's disease

Background/purposeIndividuals with Parkinson disease (PD) often exhibit decreased range of movement secondary to the disease process, which has been shown to affect articulatory movements. A number of investigations have failed to find statistically significant differences between control and disordered groups, and between speaking conditions, using traditional vowel space area measures. The purpose of the current investigation was to evaluate both between-group (PD versus control) and within-group (habitual versus clear) differences in articulatory function using a novel vowel space measure, the articulatory–acoustic vowel space (AAVS). MethodsThe novel AAVS is calculated from continuously sampled formant trajectories of connected speech. In the current study, habitual and clear speech samples from twelve individuals with PD along with habitual control speech samples from ten neurologically healthy adults were collected and acoustically analyzed. In addition, a group of listeners completed perceptual rating of speech clarity for all samples. ResultsIndividuals with PD were perceived to exhibit decreased speech clarity compared to controls. Similarly, the novel AAVS measure was significantly lower in individuals with PD. In addition, the AAVS measure significantly tracked changes between the habitual and clear conditions that were confirmed by perceptual ratings. ConclusionsIn the current study, the novel AAVS measure is shown to be sensitive to disease-related group differences and within-person changes in articulatory function of individuals with PD. Additionally, these data confirm that individuals with PD can modulate the speech motor system to increase articulatory range of motion and speech clarity when given a simple prompt. Learning outcomesThe reader will be able to (i) describe articulatory behavior observed in the speech of individuals with Parkinson disease; (ii) describe traditional measures of vowel space area and how they relate to articulation; (iii) describe a novel measure of vowel space, the articulatory–acoustic vowel space and its relationship to articulation and the perception of speech clarity.

Lexical and Acoustic Features of Maternal Utterances Addressing Preverbal Infants in Picture Book Reading Link to 5-Year-Old Children's Language Development

Research Findings: I examined the long-term association between the lexical and acoustic features of maternal utterances during book reading and the language skills of infants and children. Maternal utterances were collected from 22 mother–child dyads in picture book–reading episodes when children were ages 6–12 months and 5 years. Two aspects of language input were studied: lexical features (the amount and diversity of vocabulary, and the proportion of isolated target words) and an acoustic feature (the acoustic space of vowels). Standardized language tests were used to assess receptive vocabulary and language production abilities at age 5. The results showed that greater diversity of vocabulary and the use of fewer isolated target words during book reading with infants were associated with enhanced language skills in children 4 years later. Regression analyses showed that the proportion of isolated target words was the most potent predictor of, and acoustic vowel space also accounted for, variance in language expression skills at age 5. Maternal utterances and mothers' education jointly accounted for more than 60% of the variance in language abilities. Practice or Policy: These findings suggest that lexical and acoustic inputs in picture book reading with infants have long-term associations with children's language development throughout early childhood.

Implementing two treatment approaches to childhood dysarthria

The paucity of evidence and detail in the literature regarding speech treatment for children with dysarthria due to cerebral palsy (CP) renders it difficult for researchers to replicate studies and make further inroads into this area in need of exploration. Furthermore, for speech-language pathologists (SLPs) wishing to follow treatments that the literature indicates have promise, little guidance is available on the details of the treatments that yielded the positive results. The present article details the implementation of two treatment approaches in speech treatment research for children with dysarthria: Speech Systems Intelligibility Treatment (SSIT) and the Lee Silverman Voice Treatment LOUD (LSVT LOUD). Specific strategies, primarily for treatment, but also for outcome measurement and acoustic analysis of dysarthric speech, are described. These techniques are provided for researchers and clinicians to consider implementing in order to advance speech treatment for this population. New data from research using these approaches are presented, including findings of acoustic vowel space changes following both speech treatments.

Differences in acoustic vowel space and the perception of speech tempo

Despite various studies describing longer segment durations and slower speaking rates in females than males, there appears to be a stereotype of women speaking faster than men. To investigate the mismatch between empirical evidence and this widespread stereotype, listening experiments were conducted to test whether a relationship between perceived tempo and acoustic vowel space size might exists. If a speaker traverses a larger acoustic vowel space than another speaker within the same time then this speaker might be perceived as speaking faster. To test this, two listening experiments with either exclusively female or male speakers but with varying vowel space sizes were conducted. Listeners were asked to rate the perceived speech tempo of same-sex speaker pairs. The stimuli were manipulated to have the same segment durations and f0 contour. Results indicate that a positive correlation between acoustic vowel space size and perceived speech tempo exists. Since females exhibit on average a larger acoustic vowel space than males, it is suggested that the stereotype of faster speaking women might arise from this.

Changes in vowel articulation with subthalamic nucleus deep brain stimulation in dysarthric speakers with Parkinson's disease.

Purpose. To investigate changes in vowel articulation with the electrical deep brain stimulation (DBS) of the subthalamic nucleus (STN) in dysarthric speakers with Parkinson's disease (PD). Methods. Eight Quebec-French speakers diagnosed with idiopathic PD who had undergone STN DBS were evaluated ON-stimulation and OFF-stimulation (1 hour after DBS was turned off). Vowel articulation was compared ON-simulation versus OFF-stimulation using acoustic vowel space and formant centralization ratio, calculated with the first (F1) and second formant (F2) of the vowels /i/, /u/, and /a/. The impact of the preceding consonant context on articulation, which represents a measure of coarticulation, was also analyzed as a function of the stimulation state. Results. Maximum vowel articulation increased during ON-stimulation. Analyses also indicate that vowel articulation was modulated by the consonant context but this relationship did not change with STN DBS. Conclusions. Results suggest that STN DBS may improve articulation in dysarthric speakers with PD, in terms of range of movement. Optimization of the electrical parameters for each patient is important and may lead to improvement in speech fine motor control. However, the impact on overall speech intelligibility may still be small. Clinical considerations are discussed and new research avenues are suggested.

Phonetics as a complement to phonology in the Canadian Shift

Previous accounts of the Canadian Shift have interpreted this diachronic change in vowel pronunciation as a purely phonetic consequence of the low back LOT-THOUGHT vowel merger; however, such an analysis does not transparently explain the strong connection between the (phonological) low back merger and the subsequent (phonetic) retraction of the TRAP vowel in the acoustic vowel space. This paper addresses this issue by presenting an analysis of the shift that combines the approaches of Modified Contrastive Specification theory and the Contrastive Hierarchy—two phonological frameworks—with phonetic insights from Vowel Dispersion-Focalization theory. We propose that the catalyst of the Canadian Shift is a three-way vowel merger, in combination with a simultaneous change in the underlying feature specifications of the TRAP vowel. This results in a phonology that allows for the TRAP and DRESS vowels to succumb to the influence of the phonetic principles of dispersion and focalization. This hypothesis is illustrated by comparison of data from 59 speakers in Thunder Bay, Ontario, and Industrial Cape Breton, Nova Scotia. Our analysis predicts that a Canadian Shift-type phonetic change will occur in any North American dialect of English where the PALM-LOT-THOUGHT merger occurs, unless an intervening phonological change alters systemic contrasts.

Investigating the relationship between average speaker fundamental frequency and acoustic vowel space size

The purpose of this study is to investigate the potential relationship between speaking fundamental frequency and acoustic vowel space size, thus testing a possible perceptual source of sex-specific differences in acoustic vowel space size based on the greater inter-harmonic spacing and a poorer definition of the spectral envelope of higher pitched voices. Average fundamental frequencies and acoustic vowel spaces of 56 female German speakers are analyzed. Several parameters are used to quantify the size and shape of the vowel space defined by /iː ε aː [symbol: see text] uː/ such as the area of the polygon spanned by the five vowels, the absolute difference in F1 or F2 between /iː/ and /uː/ or /aː/, and the Euclidian distance between /iː/ and /aː/. In addition, the potential impact of nasality on the vowel space size is examined. Results reveal no significant correlation between fundamental frequency and vowel space size suggesting other factors must be responsible for the larger female acoustic vowel space.

Acoustic and articulatory analysis of French vowels produced by congenitally blind adults and sighted adults

In a previous paper [Ménard et al., J. Acoust. Soc. Am. 126, 1406-1414 (2009)], it was demonstrated that, despite enhanced auditory discrimination abilities for synthesized vowels, blind adult French speakers produced vowels that were closer together in the acoustic space than those produced by sighted adult French speakers, suggesting finer control of speech production in the sighted speakers. The goal of the present study is to further investigate the articulatory effects of visual deprivation on vowels produced by 11 blind and 11 sighted adult French speakers. Synchronous ultrasound, acoustic, and video recordings of the participants articulating the ten French oral vowels were made. Results show that sighted speakers produce vowels that are spaced significantly farther apart in the acoustic vowel space than blind speakers. Furthermore, blind speakers use smaller differences in lip protrusion but larger differences in tongue position and shape than their sighted peers to produce rounding and place of articulation contrasts. Trade-offs between lip and tongue positions were examined. Results are discussed in the light of the perception-for-action control theory.

Acoustic vowel space size and perceived speech tempo

Females speak faster than males. Although several studies have proved this stereotype to be wrong (Byrd 1994), it is still a widespread belief in many languages and within both genders. The interesting question is why. Two findings are particularly relevant regarding this stereotype: First, females reveal a greater acoustic vowel space than males (Hillenbrand et al. 1995). Second, a stimulus with a moving f0-contour is perceived as faster than the same stimulus with a monotonous contour (Lehiste 1976). From that, we might propose that if a dynamic f0 contour triggers the perception of a faster speaking rate, then a larger acoustic vowel space might have the same effect. The reason for female speakers being perceived as speaking at a faster tempo, then, is that they traverse on average a larger acoustic vowel space within the same time-frame than male speakers do. Furthermore, we could also expect a relationship between vowel space size and perceived speech tempo within the same gender. A perception test was conducted with temporally aligned stimuli from 56 female speakers who vary in their vowel space sizes. Results reveal a significant positive correlation between vowel space size and perceived tempo (r = .36, p < .001).

Acoustic vowel space and speech rate in Mandarin-speaking children with cerebral palsy

This study examines the variability in speech production in four Mandarin-speaking children: two with cerebral palsy (CP) and two typically developing (TD) from 4 to 5 years of age. Recordings collected from the picture-naming task and spontaneous interaction with adults was analyzed. Acoustic vowel space and speech rate in their production were investigated. Study findings indicated the following: (1) Due to defect in speech motor control, children with CP have a smaller overall vowel space than TD children; (2) In CP group, there are more variability of formant values of individual vowels and the vowel space of individual vowels thus overlap more; (3) There is a trend of decrease of vowel formant values in both TD and CP; (4) Children with CP tend to spend more time in speech production because of their impaired speech-motor control, in terms of syllable per minute and intelligible syllable per minute; (5) Slower speech rate seems to increase speech intelligibility in CP. However, this needs to be verified in further studies. Extended longitudinal observation can provide more complete profile of individual differences in the development of vowels and speech rate to verify these preliminary findings. The variability features in the production of children with CP provide important references in speech therapy.