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

Exposure to Canadian French Cued Speech Improves Consonant Articulation in Children With Cochlear Implants: Acoustic and Articulatory Data

PURPOSE

One of the strategies that can be used to support speech communication in deaf children is cued speech, a visual code in which manual gestures are used as additional phonological information to supplement the acoustic and labial speech information. Cued speech has been shown to improve speech perception and phonological skills. This exploratory study aims to assess whether and how cued speech reading proficiency may also have a beneficial effect on the acoustic and articulatory correlates of consonant production in children.

METHOD

Eight children with cochlear implants (from 5 to 11 years of age) and with different receptive proficiency in Canadian French Cued Speech (three children with low receptive proficiency vs. five children with high receptive proficiency) are compared to 10 children with typical hearing (from 4 to 11 years of age) on their production of stop and fricative consonants. Articulation was assessed with ultrasound measurements.

RESULTS

The preliminary results reveal that cued speech proficiency seems to sustain the development of speech production in children with cochlear implants and to improve their articulatory gestures, particularly for the place contrast in stops as well as fricatives.

CONCLUSION

This work highlights the importance of studying objective data and comparing acoustic and articulatory measurements to better characterize speech production in children.

Exploring the Age Effects on European Portuguese Vowel Production: An Ultrasound Study

For aging speech, there is limited knowledge regarding the articulatory adjustments underlying the acoustic findings observed in previous studies. In order to investigate the age-related articulatory differences in European Portuguese (EP) vowels, the present study analyzes the tongue configuration of the nine EP oral vowels (isolated context and pseudoword context) produced by 10 female speakers of two different age groups (young and old). From the tongue contours automatically segmented from the US images and manually revised, the parameters (tongue height and tongue advancement) were extracted. The results suggest that the tongue tends to be higher and more advanced for the older females compared to the younger ones for almost all vowels. Thus, the vowel articulatory space tends to be higher, advanced, and bigger with age. For older females, unlike younger females that presented a sharp reduction in the articulatory vowel space in disyllabic sequences, the vowel space tends to be more advanced for isolated vowels compared with vowels produced in disyllabic sequences. This study extends our pilot research by reporting articulatory data from more speakers based on an improved automatic method of tongue contours tracing, and it performs an inter-speaker comparison through the application of a novel normalization procedure.

Impact of visual and auditory deprivation on speech perception and production in adults

Speech perception relies on auditory and visual cues and there are strong links between speech perception and production. We aimed to evaluate the role of auditory and visual modalities on speech perception and production in adults with impaired hearing or sight versus those with normal hearing and sight. We examined speech perception and production of three isolated vowels (/i/, /y/, /u/), which were selected based on their different auditory and visual perceptual saliencies, in 12 deaf adults who used one or two cochlear implants (CIs), 14 congenitally blind adults, and 16 adults with normal sight and hearing. The results showed that the deaf adults who used a CI had worse vowel identification and discrimination perception and they also produced vowels that were less typical or precise than other participants. They had different tongue positions in speech production, which possibly partly explains the poorer quality of their spoken vowels. Blind individuals had larger lip openings and smaller lip protrusions for the rounded vowel and unrounded vowels, compared to the other participants, but they still produced vowels that were similar to those produced by the adults with normal sight and hearing. In summary, the deaf adults, even though they used CIs, had greater difficulty in producing accurate vowel targets than the blind adults, whereas the blind adults were still able to produce accurate vowel targets, even though they used different articulatory strategies.

Articulatory tongue shape analysis of Mandarin alveolar-retroflex contrast

As existing descriptions are likely too narrow to reflect a broader range of articulatory variability in Mandarin production, this study is undertaken to explore qualitative and quantitative tongue shape analysis in Mandarin sibilants. Tongue movement data are collected from 18 adult Mandarin speakers producing six sibilants in three vowel contexts. Acoustic information is also analyzed to establish the articulatory-acoustic correspondence. In addition to the common retroflex and bunched shapes, the results discovered a humped shape (e.g., a single, posterior lingual constriction) in most of Mandarin retroflex tokens. This shape is one variant of North American English /r/, but yet identified in Mandarin production. The humped shape adds to the literature and expands existing descriptions of Mandarin retroflex tongue configurations. Despite the shape differences, the general many-to-one articulatory-acoustic mappings also holds true for Mandarin retroflexes. However, while curvature analyses based on Cartesian coordinates significantly differentiated contrastive shapes in retroflex production, these analyses were not equally reliable in separating the alveolar-retroflex distinction, likely due to individual differences. The tongue contour changes in the place contrast were instead quantified by calculations with polar coordinates. The preliminary findings on Mandarin retroflexes are discussed in terms of vocal tract morphology, with possible lip protrusion.

F0-related head movement in blind versus sighted speakers

This study investigated the relationship between head movement and fundamental frequency (F0) during speech by comparing continuous speech of congenitally blind and sighted speakers from YouTube videos. Positive correlations were found between F0 (measured in semitones) and vertical head movement for both speaker groups, with a stronger correlation for blind speakers. In addition, larger head movements and larger head movement per semitone ratios were observed for sighted speakers. These results suggest that physiological processes may account for part of the F0-related head movement and that sighted speakers use the visual modality to communicate F0 information through augmented head movement.

Visualization and quantification of tongue movement during articulation: Is ultrasound a valid alternative to magnetic resonance imaging?

BACKGROUND

Quality of life in tumour patients following combined ablative and reconstructive head and neck surgery varies significantly. This is at least partially due to differences in speech and swallowing function. A tool to objectively evaluate articulation by magnetic resonance imaging (MRI) has now been tested alongside ultrasound examination.

PATIENTS AND METHODS

A standardized sequence of phonemes from the German language was established in 20 healthy volunteers and recorded in different planes by MRI and ultrasound. Phonemes were identified through recognition of typical tongue configurations by two different observers. An algorithm for metric analysis of articulation in terms of distances and angles for five extreme points on the tongue (anterior, posterior, cranial and two basal corners) was designed. The findings in these volunteers were subsequently compared with the results of an examination of a tumour patient.

RESULTS

Physiological articulation was visualized and evaluated both by MRI and ultrasound. There was a high intra-class correlation coefficient for measurements between independent observers. Tongue position for certain phonemes was mostly constant in healthy patients of different age groups, with gender-specific differences. In a first comparison, tongue position in a patient with tongue cancer differed significantly from this position, both pre- and postoperatively. In agreement with clinical articulation quality, the tongue position of the patient returned to almost normal within 12 months postoperatively.

CONCLUSION

Both ultrasound and MRI are appropriate instruments for visualization of articulation and objective measurements to evaluate speech in tumour patients. Whilst MRI is more precise and can identify more subtle differences, ultrasound is a valid alternative due to its wider availability and broader applicability.

Enhanced perception of pitch changes in speech and music in early blind adults

It is well known that congenitally blind adults have enhanced auditory processing for some tasks. For instance, they show supra-normal capacity to perceive accelerated speech. However, only a few studies have investigated basic auditory processing in this population. In this study, we investigated if pitch processing enhancement in the blind is a domain-general or domain-specific phenomenon, and if pitch processing shares the same properties as in the sighted regarding how scores from different domains are associated. Fifteen congenitally blind adults and fifteen sighted adults participated in the study. We first created a set of personalized native and non-native vowel stimuli using an identification and rating task. Then, an adaptive discrimination paradigm was used to determine the frequency difference limen for pitch direction identification of speech (native and non-native vowels) and non-speech stimuli (musical instruments and pure tones). The results show that the blind participants had better discrimination thresholds than controls for native vowels, music stimuli, and pure tones. Whereas within the blind group, the discrimination thresholds were smaller for musical stimuli than speech stimuli, replicating previous findings in sighted participants, we did not find this effect in the current control group. Further analyses indicate that older sighted participants show higher thresholds for instrument sounds compared to speech sounds. This effect of age was not found in the blind group. Moreover, the scores across domains were not associated to the same extent in the blind as they were in the sighted. In conclusion, in addition to providing further evidence of compensatory auditory mechanisms in early blind individuals, our results point to differences in how auditory processing is modulated in this population.

Visual Speech Perception Cues Constrain Patterns of Articulatory Variation and Sound Change

What are the factors that contribute to (or inhibit) diachronic sound change? While acoustically motivated sound changes are well-documented, research on the articulatory and audiovisual-perceptual aspects of sound change is limited. This paper investigates the interaction of articulatory variation and audiovisual speech perception in the Northern Cities Vowel Shift (NCVS), a pattern of sound change observed in the Great Lakes region of the United States. We focus specifically on the maintenance of the contrast between the vowels /ɑ/ and /ɔ/, both of which are fronted as a result of the NCVS. We present results from two experiments designed to test how the NCVS is produced and perceived. In the first experiment, we present data from an articulatory and acoustic analysis of the production of fronted /ɑ/ and /ɔ/. We find that some speakers distinguish /ɔ/ from /ɑ/ with a combination of both tongue position and lip rounding, while others do so using either tongue position or lip rounding alone. For speakers who distinguish /ɔ/ from /ɑ/ along only one articulatory dimension, /ɑ/ and /ɔ/ are acoustically more similar than for speakers who produce multiple articulatory distinctions. While all three groups of speakers maintain some degree of acoustic contrast between the vowels, the question is raised as to whether these articulatory strategies differ in their perceptibility. In the perception experiment, we test the hypothesis that visual speech cues play a role in maintaining contrast between the two sounds. The results of this experiment suggest that articulatory configurations in which /ɔ/ is produced with unround lips are perceptually weaker than those in which /ɔ/ is produced with rounding, even though these configurations result in acoustically similar output. We argue that these findings have implications for theories of sound change and variation in at least two respects: (1) visual cues can shape phonological systems through misperception-based sound change, and (2) phonological systems may be optimized not only for auditory but also for visual perceptibility.

Maintaining Distinctiveness at Increased Speaking Rates: A Comparison between Congenitally Blind and Sighted Speakers

OBJECTIVES

The effects of increased speaking rates on vowels have been well documented in sighted adults. It has been reported that in fast speech, vowels are less widely spaced acoustically than in their citation form. Vowel space compression has also been reported in congenitally blind speakers. The objective of the study was to investigate the interaction of vision and speaking rate in adult speakers.

PATIENTS AND METHODS

Contrast distances between vowels were examined in conversational and fast speech produced by 10 congenitally blind and 10 sighted French-Canadian adults. Acoustic analyses were carried out.

RESULTS

Compared with the sighted speakers, in the fast speaking condition, the blind speakers produced more vowels with contrast along the height, place of articulation, and rounding features located within the auditory target regions typical of French vowels.

CONCLUSION

Blind speakers relied more heavily than sighted speakers on auditory properties of vowels to maintain perceptual distinctiveness.

Visual speech alters the discrimination and identification of non-intact auditory speech in children with hearing loss

OBJECTIVES

Understanding spoken language is an audiovisual event that depends critically on the ability to discriminate and identify phonemes yet we have little evidence about the role of early auditory experience and visual speech on the development of these fundamental perceptual skills. Objectives of this research were to determine 1) how visual speech influences phoneme discrimination and identification; 2) whether visual speech influences these two processes in a like manner, such that discrimination predicts identification; and 3) how the degree of hearing loss affects this relationship. Such evidence is crucial for developing effective intervention strategies to mitigate the effects of hearing loss on language development.

METHODS

Participants were 58 children with early-onset sensorineural hearing loss (CHL, 53% girls, M = 9;4 yrs) and 58 children with normal hearing (CNH, 53% girls, M = 9;4 yrs). Test items were consonant-vowel (CV) syllables and nonwords with intact visual speech coupled to non-intact auditory speech (excised onsets) as, for example, an intact consonant/rhyme in the visual track (Baa or Baz) coupled to non-intact onset/rhyme in the auditory track (/-B/aa or/-B/az). The items started with an easy-to-speechread/B/or difficult-to-speechread/G/onset and were presented in the auditory (static face) vs. audiovisual (dynamic face) modes. We assessed discrimination for intact vs. non-intact different pairs (e.g., Baa:/-B/aa). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more same-as opposed to different-responses in the audiovisual than auditory mode. We assessed identification by repetition of nonwords with non-intact onsets (e.g.,/-B/az). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more Baz-as opposed to az- responses in the audiovisual than auditory mode.

RESULTS

Performance in the audiovisual mode showed more same responses for the intact vs. non-intact different pairs (e.g., Baa:/-B/aa) and more intact onset responses for nonword repetition (Baz for/-B/az). Thus visual speech altered both discrimination and identification in the CHL-to a large extent for the/B/onsets but only minimally for the/G/onsets. The CHL identified the stimuli similarly to the CNH but did not discriminate the stimuli similarly. A bias-free measure of the children's discrimination skills (i.e., d' analysis) revealed that the CHL had greater difficulty discriminating intact from non-intact speech in both modes. As the degree of HL worsened, the ability to discriminate the intact vs. non-intact onsets in the auditory mode worsened. Discrimination ability in CHL significantly predicted their identification of the onsets-even after variation due to the other variables was controlled.

CONCLUSIONS

These results clearly established that visual speech can fill in non-intact auditory speech, and this effect, in turn, made the non-intact onsets more difficult to discriminate from intact speech and more likely to be perceived as intact. Such results 1) demonstrate the value of visual speech at multiple levels of linguistic processing and 2) support intervention programs that view visual speech as a powerful asset for developing spoken language in CHL.

Phonological Priming in Children with Hearing Loss: Effect of Speech Mode, Fidelity, and Lexical Status

OBJECTIVES

This research determined (1) how phonological priming of picture naming was affected by the mode (auditory-visual [AV] versus auditory), fidelity (intact versus nonintact auditory onsets), and lexical status (words versus nonwords) of speech stimuli in children with prelingual sensorineural hearing impairment (CHI) versus children with normal hearing (CNH) and (2) how the degree of HI, auditory word recognition, and age influenced results in CHI. Note that the AV stimuli were not the traditional bimodal input but instead they consisted of an intact consonant/rhyme in the visual track coupled to a nonintact onset/rhyme in the auditory track. Example stimuli for the word bag are (1) AV: intact visual (b/ag) coupled to nonintact auditory (-b/ag) and 2) auditory: static face coupled to the same nonintact auditory (-b/ag). The question was whether the intact visual speech would "restore or fill-in" the nonintact auditory speech in which case performance for the same auditory stimulus would differ depending on the presence/absence of visual speech.

DESIGN

Participants were 62 CHI and 62 CNH whose ages had a group mean and group distribution akin to that in the CHI group. Ages ranged from 4 to 14 years. All participants met the following criteria: (1) spoke English as a native language, (2) communicated successfully aurally/orally, and (3) had no diagnosed or suspected disabilities other than HI and its accompanying verbal problems. The phonological priming of picture naming was assessed with the multimodal picture word task.

RESULTS

Both CHI and CNH showed greater phonological priming from high than low-fidelity stimuli and from AV than auditory speech. These overall fidelity and mode effects did not differ in the CHI versus CNH-thus these CHI appeared to have sufficiently well-specified phonological onset representations to support priming, and visual speech did not appear to be a disproportionately important source of the CHI's phonological knowledge. Two exceptions occurred, however. First-with regard to lexical status-both the CHI and CNH showed significantly greater phonological priming from the nonwords than words, a pattern consistent with the prediction that children are more aware of phonetics-phonology content for nonwords. This overall pattern of similarity between the groups was qualified by the finding that CHI showed more nearly equal priming by the high- versus low-fidelity nonwords than the CNH; in other words, the CHI were less affected by the fidelity of the auditory input for nonwords. Second, auditory word recognition-but not degree of HI or age-uniquely influenced phonological priming by the AV nonwords.

CONCLUSIONS

With minor exceptions, phonological priming in CHI and CNH showed more similarities than differences. Importantly, this research documented that the addition of visual speech significantly increased phonological priming in both groups. Clinically these data support intervention programs that view visual speech as a powerful asset for developing spoken language in CHI.

Speaking Clearly for the Blind: Acoustic and Articulatory Correlates of Speaking Conditions in Sighted and Congenitally Blind Speakers

Compared to conversational speech, clear speech is produced with longer vowel duration, greater intensity, increased contrasts between vowel categories, and decreased dispersion within vowel categories. Those acoustic correlates are produced by larger movements of the orofacial articulators, including visible (lips) and invisible (tongue) articulators. Thus, clear speech provides the listener with audible and visual cues that are used to increase the overall intelligibility of speech produced by the speaker. It is unclear how those cues are produced by visually impaired speakers who never had access to vision. In this paper, we investigate the acoustic and articulatory correlates of vowels in clear versus conversational speech, and in sighted and congenitally blind speakers. Participants were recorded using electroarticulography while producing multiple repetitions of the ten Quebec French oral vowels in carrier sentences in both speaking conditions. Articulatory variables (lip, jaw, and tongue positions) as well as acoustic variables (contrasts between vowels, within-vowel dispersion, pitch, duration, and intensity) were measured. Lip movements were larger when going from conversational to clear speech in sighted speakers only. On the other hand, tongue movements were affected to a larger extent in blind speakers compared to their sighted peers. These findings confirm that vision plays an important role in the maintenance of speech intelligibility.

Compensation for a lip-tube perturbation in 4-year-olds: Articulatory, acoustic, and perceptual data analyzed in comparison with adults

The nature of the speech goal in children was investigated in a study of compensation strategies for a lip-tube perturbation. Acoustic, articulatory, and perceptual analyses of the vowels /y/ and /u/ produced by ten 4-year-old French speakers and ten adult French speakers were conducted under two conditions: normal and with a large tube inserted between the lips. Ultrasound and acoustic recordings of isolated vowels were made in the normal condition before any perturbation, for each of the trials in the perturbed condition, and in the normal condition after the perturbed trials. Data revealed that adult participants moved their tongues in the perturbed condition more than children did. The perturbation was generally at least partly compensated for during the perturbed trials in adults, but children did not show a typical learning effect. In particular, unsystematic improvements were observed during the sequence of perturbed trials, and after-effects were not clear in the articulatory domain. This suggests that children may establish associative links between multisensory phonemic representations and articulatory maneuvers, but those links may mainly rely on trial-to-trial, error-based feedback correction mechanisms rather than on the internal model of the speech production apparatus, as they are in adults.

Effects of Congenital Visual Deprivation on the Auditory Perception of Anticipatory Labial Coarticulation

OBJECTIVE

It has been shown previously that congenitally blind francophone adults had higher auditory discrimination scores than sighted adults. It is unclear, however, if, compared to their sighted peers, blind speakers display an increased ability to detect anticipatory acoustic cues. In this paper, this ability is investigated in both speaker groups.

METHODS

Using the gating paradigm, /izi/ and /izy/ sequences were truncated to include a variable duration of the vowel. The sequences were used as stimuli in an auditory identification test. Seventeen congenitally blind adults (9 females and 8 males) and 17 sighted controls were recruited. Their task was to identify the second vowel of the sequence.

RESULTS

Results show that all participants could reliably identify the rounded vowel prior to its acoustic onset, but steeper identification slopes were found for sighted listeners than for blind listeners.

CONCLUSION

The difference in identification slopes likely suggests that sighted speakers display finer abilities to perceptually follow the decreasing values of the frication noise, compared to blind speakers.

Effects of blindness on production-perception relationships: Compensation strategies for a lip-tube perturbation of the French [u]

The impact of congenital visual deprivation on speech production in adults was examined in an ultrasound study of compensation strategies for lip-tube perturbation. Acoustic and articulatory analyses of the rounded vowel /u/ produced by 12 congenitally blind adult French speakers and 11 sighted adult French speakers were conducted under two conditions: normal and perturbed (with a 25-mm diameter tube inserted between the lips). Vowels were produced with auditory feedback and without auditory feedback (masked noise) to evaluate the extent to which both groups relied on this type of feedback to control speech movements. The acoustic analyses revealed that all participants mainly altered F2 and F0 and, to a lesser extent, F1 in the perturbed condition - only when auditory feedback was available. There were group differences in the articulatory strategies recruited to compensate; while all speakers moved their tongues more backward in the perturbed condition, blind speakers modified tongue-shape parameters to a greater extent than sighted speakers.

Articulatory and acoustic correlates of contrastive focus in congenitally blind adults and sighted adults

PURPOSE

The role of vision in speech representation was investigated in congenitally blind speakers and sighted speakers by studying the correlates of contrastive focus, a prosodic condition in which phonemic contrasts are enhanced. It has been reported that the lips (visible articulators) are less involved in implementing the rounding feature for blind speakers. If the weight of visible gestures in speech representation is reduced in blind speakers, they should show different strategies to mark focus-induced prominence.

METHOD

Nine congenitally blind French speakers and 9 sighted French speakers were recorded while uttering sentences in neutral and contrastive focus conditions. Internal lip area, upper lip protrusion, and acoustic values (formants, fundamental frequency, duration, and intensity) were measured.

RESULTS

In the acoustic domain, both groups signaled focus by using comparable values of fundamental frequency, intensity, and duration. Formant values in sighted speakers were more affected by the prosodic condition. In the articulatory domain, sighted speakers significantly altered lip geometry in the contrastive focus condition compared with the neutral condition, whereas blind speakers did not.

CONCLUSION

These results suggest that implementation of prosodic focus is affected by congenital visual deprivation. The authors discuss how these findings can be interpreted in the framework of the perception-for-action-control theory.