Vowel Portion Research Articles

Probing the phonological-coding deficit in dyslexia with vowel length perception

There is an established linkage between dyslexia and anomalous processing of speech sounds. We probed this in a Danish language context with vowel length tasks based on “kugle” ball /ku:lə/ and sequential deletions of the vowel portion to yield “kulde” coldness /kulə/. Vowel length continua are methodologically advantageous as they do not involve the perception of a sudden phonetic change that may instead tap other auditory processing abilities. Identification and discrimination tasks were administered to tertiary (n = 28), reading impaired (n = 26), and lower secondary students (n = 20), and the latter were approximately aged matched to the reading-impaired group. Identification functions derived from regression modelling of the responses showed that the dyslexics had significantly flatter curves than the other groups. Moreover, the secondary and dyslexic groups differed at the long vowel extremity of the continuum. Discrimination results showed that mean peak sensitivity of the tertiary students was higher than that of the secondary and dyslexic students. These results indicate that the phonological-coding deficit observed in dyslexics may be indexed by vowel length identification. Furthermore, identification results suggest that the nature of the phonological-coding deficit concomitant with dyslexia may stem from a lack of precision in processing the minimally modified longer vowel stimuli.

Determining spectral stability in vowels: A comparison and assessment of different metrics

This study investigated the performance of several metrics used to evaluate spectral stability in vowels. Four metrics suggested in the literature and a newly developed one were tested and compared to the traditional method of associating the spectrally stable portion with the middle of the vowel. First, synthetic stimuli whose spectrally stable portion had been defined in advance were used to evaluate the potential of the different metrics to capture spectral stability. Second, the output of the different metrics on the acoustic measurements obtained in the vowel portions identified as spectrally stable was compared on both synthesized and natural speech. It is clear that higher-dimensional features are needed to capture spectral stability and that the best-performing metrics yield acoustic measurements that are similar to those obtained in the middle of the vowel. This study empirically validates long-standing intuitions about the validity of selecting the middle section of vowels as the preferred method to identify the spectrally stable region in vowels.

Acoustic Analysis of Taiwanese Tones in Esophageal Speech and Pneumatic Artificial Laryngeal Speech.

This study examined the acoustic properties of Taiwanese (Southern Min) lexical tones produced in esophageal speech (ES) and pneumatic artificial laryngeal speech (PAL), including onset fundamental frequency (F0), slope of F0 contour, duration, and amplitude (intensity) of the vowel portion of syllables carrying seven Taiwanese tones. Seven ES speakers, seven PAL speakers, and 18 normal laryngeal (NL) speakers (all male) read aloud target syllables carrying the tones in monosyllables, disyllables, and sentences. Acoustic features were measured with Praat. Acoustic analysis revealed (a) no significant effects of linguistic level on acoustic parameters except for duration, which generally significantly decreased from monosyllables to disyllables to sentences for Tones 1 and 5; (b) significant differences across the speaker groups in onset F0 (PAL > ES > NL), duration (PAL > NL and PAL > ES for all tones), and mean amplitude (PAL > NL > ES); and (c) no significant difference in mean slope of F0 contour across the speaker groups. These preliminary data on acoustic properties of Taiwanese tones produced by ES and PAL speakers could facilitate the design of therapeutic strategies for improving the intelligibility of alaryngeal lexical tones. Further studies are recommended to examine the relative perceptual importance of the acoustic parameters.

Vowel Production in Prelingually Deafened Mandarin-Speaking Children With Cochlear Implants

Purpose The purpose of this study was to characterize the acoustic profile and to evaluate the intelligibility of vowel productions in prelingually deafened, Mandarin-speaking children with cochlear implants (CIs). Method Twenty-five children with CIs and 20 age-matched children with normal hearing (NH) were recorded producing a list of Mandarin disyllabic and trisyllabic words containing 20 Mandarin vowels [a, i, u, y, ɤ, ɿ, ʅ, ai, ei, ia, ie, ye, ua, uo, au, ou, iau, iou, uai, uei] located in the first consonant-vowel syllable. The children with CIs were all prelingually deafened and received unilateral implantation before 7 years of age with an average length of CI use of 4.54 years. In the acoustic analysis, the first two formants (F1 and F2) were extracted at seven equidistant time locations for the tested vowels. The durational and spectral features were compared between the CI and NH groups. In the vowel intelligibility task, the extracted vowel portions in both NH and CI children were presented to six Mandarin-speaking, NH adult listeners for identification. Results The acoustic analysis revealed that the children with CIs deviated from the NH controls in the acoustic features for both single vowels and compound vowels. The acoustic deviations were reflected in longer duration, more scattered vowel categories, smaller vowel space area, and distinct formant trajectories in the children with CIs in comparison to NH controls. The vowel intelligibility results showed that the recognition accuracy of the vowels produced by the children with CIs was significantly lower than that of the NH children. The confusion pattern of vowel recognition in the children with CIs generally followed that in the NH children. Conclusion Our data suggested that the prelingually deafened children with CIs, with a relatively long duration of CI experience, still showed measurable acoustic deviations and lower intelligibility in vowel productions in comparison to the NH children.

Variability of formant values at different time points of vowels

Vowel inherent spectral change research has led to two apparently contradictory conclusions about the appropriate representation of vowels: perception studies support a dual-target model of vowels, while production studies focus on calculating higher-fidelity continuous formant contours. This study explores production data in a new way by analyzing where in vowel duration variability is lowest across tokens. Portions of vowels that are less variable across tokens are assumed reflect greater importance to or planning by speakers. Born-and-raised Wisconsinites aged 18–30 were recorded reading a word-in-frame reading list eliciting 30 tokens of 14 American English vowels in the context /hVd/. F1 and F2 were sampled at 50 evenly spaced intervals for each vowel, covering the entire duration. For every speaker, the standard deviations of F1 and F2 were taken separately at every sample. Variability was analyzed as a function of time point. An upturned parabola pattern suggests a single target, a downturned parabola pattern suggests a dual target, and a horizontal pattern suggests continuous specification. For monophthongs, variability is found to be convex, and it is concave for diphthongs. This analysis does not support a dual-target model for monophthongs.

Acoustic Features and Cortical Auditory Evoked Potentials according to Emotional Statues of /u/, /a/, /i/ Vowels.

Background and ObjectivesAlthough Ling 6 sounds are often used in the rehabilitation process, its acoustic features have not been fully analyzed and represented in cortical responses. Current study was aimed to analyze acoustic features according to gender and emotional statuses of core vowels of Ling 6 sounds, /u/, /a/, and /i/. Cortical auditory evoked potentials (CAEPs) were also observed in those vowels. Subjects and MethodsVowel sounds /u/, /a/, and /i/ out of Ling 6 sounds representing low, middle and high frequencies were recorded from normal 20 young adults. The participants watched relevant videos for 4-5 minutes in order for them to sympathize emotions with anger (A), happiness (H), and sadness (S) before producing vowels. And without any emotional salience, neutrally production was performed. The recording was extracted for 500 ms to select pure vowel portion of production. For analysis of CAEP, the latencies and amplitudes of P1, N1, P2, N2, N1-P2 were analyzed. ResultsIntensities of /u/, /a/, and /i/ were 61.47, 63.38, and 60.55 dB. The intensities of neutral (N), H, A, S were 60.60, 65.43, 64.21, and 55.75 dB for vowel /u/, vowel /a/ were 61.80, 68.98, 66.50, and 56.23 dB, and vowel /i/ were 59.34, 64.90, 61.90, and 56.05 dB. The statistical significances for vowel and emotion were found but not for gender. The fundamental frequency (F0) of vowels for N, A, H, and S were 168.04, 174.93, 182.72, and 149.76 Hz and the first formant were 743.75, 815.59, 823.32, and 667.62 Hz. The statistical significance of F0 was found by vowel, emotion, and gender. The latencies and amplitudes of CAEP components did not show any statistical significance according to vowel.ConclusionsLing 6 sounds should be produced consistently in the rehabilitation process for considering their difference of intensities and frequencies according to speaker’s emotions and gender. The vowels seemed to be interpreted as tonal stimuli for CAEP components of this study with similar acoustic features among them. Careful selection of materials is necessary to observe meaningful conclusion of CAEP measurement with vowel stimuli.

Analyses of Sustained Vowels in Down Syndrome (DS): A Case Study Using Spectrograms and Perturbation Data to Investigate Voice Quality in Four Adults With DS

Automatic acoustic measures of voice quality in people with Down syndrome (DS) do not reliably reflect perceived voice qualities. This study used acoustic data and visual spectral data to investigate the relationship between perceived voice qualities and acoustic measures. Participants were four young adults (two males, two females; mean age 23.8 years) with DS and severe learning disabilities, at least one of whom had a hearing impairment. Participants imitated sustained /i/, /u/, and /a/ vowels at predetermined target pitches within their vocal range. Medial portions of vowels were analyzed, using Praat, for fundamental frequency, harmonics-to-noise ratio, jitter, and shimmer. Spectrograms were used to identify the presence and the duration of subharmonics at onset and offset, and mid-vowel. The presence of diplophonia was assessed by auditory evaluation. Perturbation data were highest for /a/ vowels and lowest for /u/ vowels. Intermittent productions of subharmonics were evident in spectrograms, some of which coincided with perceived diplophonia. The incidence, location, duration, and intensity of subharmonics differed between the four participants. Although the acoustic data do not clearly indicate atypical phonation, diplophonia and subharmonics reflect nonmodal phonation. The findings suggest that these may contribute to different perceived voice qualities in the study group and that these qualities may result from intermittent involvement of supraglottal structures. Further research is required to confirm the findings in the wider DS population, and to assess the relationships between voice quality, vowel type, and physiological measures.

How Stressful Is “Deep Bubbling”?

Water resistance therapy by phonating through a tube into the water is used to treat dysphonia. Deep submersion (≥10 cm in water, "deep bubbling") is used for hypofunctional voice disorders. Using it with caution is recommended to avoid vocal overloading. This experimental study aimed to investigate how strenuous "deep bubbling" is. Fourteen subjects, half of them with voice training, repeated the syllable [pa:] in comfortable speaking pitch and loudness, loudly, and in strained voice. Thereafter, they phonated a vowel-like sound both in comfortable loudness and loudly into a glass resonance tube immersed 10 cm into the water. Oral pressure, contact quotient (CQ, calculated from electroglottographic signal), and sound pressure level were studied. The peak oral pressure P(oral) during [p] and shuttering of the outer end of the tube was measured to estimate the subglottic pressure P(sub) and the mean P(oral) during vowel portions to enable calculation of transglottic pressure P(trans). Sensations during phonation were reported with an open-ended interview. P(sub) and P(oral) were higher in "deep bubbling" and P(trans) lower than in loud syllable phonation, but the CQ did not differ significantly. Similar results were obtained for the comparison between loud "deep bubbling" and strained phonation, although P(sub) did not differ significantly. Most of the subjects reported "deep bubbling" to be stressful only for respiratory and lip muscles. No big differences were found between trained and untrained subjects. The CQ values suggest that "deep bubbling" may increase vocal fold loading. Further studies should address impact stress during water resistance exercises.

Electrophysiological Measures of Auditory Brainstem Responses to Hindi Speech Stimulus in Indian Adults

Abstract Objectives: Speech evoked auditory brainstem responses (spABR) assesses brainstem ability to encode speech. However, speech representations at brainstem are affected by acoustic properties of speech, language background and experiences. Hindi has considerable acoustic differences that may evoke dissimilar ABR pattern. Therefore, our objective was to investigate the spABR to Hindi stimulus in normal hearing adults. Design: The 5 formants Hindi stop |da| of 40ms was synthesized to elicit ABRs from 50 normal hearing adults with mean age of 22.7 (SD=2.3) years in the age range 18-25 years. The sub-cortical response latency & amplitude to consonant and vowel portion of the stimulus were recorded. Results: The spABR elicited distinctive peaks for stimulus component. The consonant portion evoked peak V and vowel portion elicited the frequency following response (FFR). The mean, median, standard deviation, minimum, maximum and 95% confidence interval of peak latency & amplitude were measured. ANOVA was studied at 5% significance levels between the current spABR and western data. Conclusions: The obtained brainstem response timing and amplitude values of transient and sustained portion of stimulus are in line with the western reports. However, considering the acoustic differences in Indian languages, culturally & linguistically sensitive stimulus should possibly be developed and norms be established.

Neurophysiologic measures of auditory brainstem responses to Hindi speech stimulus in typically developing children

Context: Speech evoked auditory brain stem responses (spABR) are used to assess brain stem ability to encode speech. However, brain stem representations of speech sound are affected by acoustic differences of speech, language background and experiences. Hence, linguistically and culturally specific stimulus should be used. Therefore, there is need to investigate the brain stem encoding of Hindi speech sound. Objective: The purpose of the study was to investigate the spABR to Hindi stimulus in typically developing children. Methods and Material: Total 25 atypical children of the mean age of 6.3 years with SD 2.3 years in the age range of 8-12 years were recruited. A 40ms duration Hindi stop phoneme of CV combination |da| was synthesized to gain response of consonant (transient) and vowel (sustained) portion of speech stimulus from all subjects. Results: The spABR latencies and amplitudes of discrete peaks as well as the latency, amplitude, area & slope of V-A complex were measured. The stimulus to response timing and spectral magnitudes of periodic portion were also calculated. The mean, median, standard deviation, minimum, maximum and 95% confidence interval values were calculated. Conclusions: The obtained spABR values suggest faithful representation of acoustic characteristic of speech at brain stem level. These values are found to be similar with previous reports. Hence, spABR can serve as important tools in the diagnostic work up of auditory processing deficits in children to understand speech perception and production abilities.

Effects of spectral content on Horii Oral-Nasal Coupling scores in children.

A miniature accelerometer and microphone can be used to obtain Horii Oral-Nasal Coupling (HONC) scores to objectively measure nasalization of speech. While this instrumentation compares favorably in terms of size and cost relative to other objective measures of nasality, the metric has not been well characterized in children. Furthermore, the measure is known to be affected by vowel loading, as speech loaded with "high" vowels is consistently scored as more nasal than speech loaded with "low" vowels. Filtering the signals used in computation of the HONC score to better isolate the correlates of nasalization has been shown to reduce vowel-related effects on the metric, but the efficacy of filtering has thus far only been explored in adults. Here, HONC scores for running speech and the vowel portions of consonant-vowel-consonant tokens were calculated for the speech of 26 children, aged 4-9 yrs. Scores were computed using the broadband accelerometer and speech signals, as well as using filtered, low-frequency versions of these signals. HONC scores obtained using both broadband and filtered signals resulted in well-separated scores for nasal and non-nasal speech. HONC scores computed using filtered signals were found to exhibit less within-participant variability.

Lifetime benefits of musical training.

Lifetime benefits of musical training.

Perceptual contribution of vowel sub-segments to Mandarin tone identification

Recent noise-replacement studies showed that (1) vowels carried more intelligibility information in Mandarin sentence recognition, and (2) a little vowel onset portion could significantly increase the intelligibility when it was added to the consonant-only Mandarin sentences. This study further evaluated the perceptual contribution of vowel sub-segments to Mandarin tone identification. The original duration-normalized vowels (FULL) were modified to produce two types of stimulus, i.e., (1) Left-only [LO (p)], which preserved p = 10% to 50% of the initial vowel portion, and replaced the rest vowel portion with speech-shaped noise (SSN), and (2) center-only [CO (p)], which preserved p = 15% to 60% of the center vowel portion, and replaced the rest initial and final vowel portions with SSN. Tone identification scores were collected from 20 normal-hearing native-Mandarin listeners. Results in the present study showed that (1) Mandarin tone perception at the LO (10%) condition was slightly higher than the chance level (i.e., 25%); (2) tone identification at the CO (60%) condition was not significantly different with that at the FULL condition. These findings suggest that vowel onset portion provides information redundant to vowel centers for Mandarin tone identification, and vowel centers contain sufficient information for reliable Mandarin tone identification.

Acoustic Predictors of Intelligibility for Segmentally Interrupted Speech: Temporal Envelope, Voicing, and Duration

Temporal interruption limits the perception of speech to isolated temporal glimpses. An analysis was conducted to determine the acoustic parameter that best predicts speech recognition from temporal fragments that preserve different types of speech information-namely, consonants and vowels. Young listeners with normal hearing previously completed word and sentence recognition tasks that required them to repeat word and sentence material that was temporally interrupted. Interruptions were designed to replace various portions of consonants or vowels with low-level noise. Acoustic analysis of preserved consonant and vowel segments was conducted to investigate the role of the preserved temporal envelope, voicing, and speech duration in predicting performance. Results demonstrate that the temporal envelope, predominantly from vowels, is most important for sentence recognition and largely predicts results across consonant and vowel conditions. In contrast, for isolated words the proportion of speech preserved was the best predictor of performance regardless of whether glimpses were from consonants or vowels. These findings suggest consideration of the vowel temporal envelope in speech transmission and amplification technologies for improving the intelligibility of temporally interrupted sentences.

Tone recognition in continuous Mandarin Chinese

Tones are important characteristics of Mandarin Chinese for conveying lexical meaning. Thus tone recognition, either explicit or implicit, is required for automatic recognition of Mandarin. Most literature on machine recognition of tones is based on syllables spoken in isolation or even machine-synthesized voices. This is likely due to the difficulty of recognizing tones from syllables extracted from conversational speech, even for native speakers of Mandarin. In this study, human and machine recognition of tones from continuous speech is evaluated and compared for four conditions: 1, vowel portions of syllables; 2, complete syllables; 3, syllable pairs; 4, groupings of three syllables. The syllables are extracted from the RASC-863 continuous Mandarin Chinese database. The human listeners are all native speakers of Mandarin. The automatic recognition is based on either Hidden Markov Models, or neural networks, and a combination of spectral/temporal, energy, and pitch features. When very little context is used (i.e., vowel segments only) the human and machine performance is comparable. However, as the context interval is increased, the human performance is better than the best machine performance.

Effects of the distribution of acoustic cues on infants' perception of sibilants

A current theoretical view proposes that infants converge on the speech categories of their native language by attending to frequency distributions that occur in the acoustic input. To date, the only empirical support for this statistical learning hypothesis comes from studies where a single, salient dimension was manipulated. Additional evidence is sought here, by introducing a less salient pair of categories supported by multiple cues. We exposed English-learning infants to a multi-cue bidimensional grid ranging between retroflex and alveolopalatal sibilants in prevocalic position. This contrast is substantially more difficult according to previous cross-linguistic and perceptual research, and its perception is driven by cues in both the consonantal and the following vowel portions. Infants heard one of two distributions (flat, or with two peaks), and were tested with sounds varying along only one dimension. Infants' responses differed depending on the familiarization distribution, and their performance was equally good for the vocalic and the frication dimension, lending some support to the statistical hypothesis even in this harder learning situation. However, learning was restricted to the retroflex category, and a control experiment showed that lack of learning for the alveolopalatal category was not due to the presence of a competing category. Thus, these results contribute fundamental evidence on the extent and limitations of the statistical hypothesis as an explanation for infants' perceptual tuning.

Speech Evoked Auditory Brainstem Responses: A New Tool to Study Brainstem Encoding of Speech Sounds

The neural encoding of speech sound begins in the auditory nerve and travels to the auditory brainstem. Non speech stimuli such as click or tone bursts stimulus are used to check the auditory neural integrity routinely. Recently Speech evoked Auditory Brainstem measures (ABR) are being used as a tool to study the brainstem processing of Speech sounds. The aim of the study was to study the Speech evoked ABR to a consonant vowel (CV) stimulus. 30 subjects with normal hearing participated for the study. Speech evoked ABR were measured to a CV stimulus in all the participants. The speech stimulus used was a 40ms synthesized/da/sound. The consonant and vowel portion was analysed separately. Speech evoked ABR was present in all the normal hearing subjects. The consonant portion of the stimulus elicited peak V in response waveform. Response to the vowel portion elicited a frequency following response (FFR). The FFR further showed a coding of the fundamental frequency (F0) and the first formant frequency (F1). The results of the present study throw light on the processing of speech in brainstem. The understanding of speech evoked ABR has other applications both in research as well as in clinical purposes. Such understanding is specially important if one is interested in studying the central auditory system function.

Speaker and listener variables affecting second language vowel intelligibility.

Research investigating the development of second language (L2) phonology often relies on native speaker evaluation of L2 productions. However, listener variables that might affect these judgments remain little understood. For example, Levi et al. (2007) argued that the lexical frequency of L2 speech tokens influences listeners. However, they used somewhat incommensurate measures to compare listener vis‐a‐vis speaker variables. The present study investigates the impact of speaker and listener variables on English vowel intelligibility using three distinct listening tasks and compares three speaker groups: first language (L1) English, L1 Mandarin, and L1 Slavic. Speakers repeated a word list comprising 10 target English vowels, each embedded in three separate monosyllabic verbs and varying in terms of lexical familiarity for speakers and lexical frequency for listeners. L1 English judges identified the recorded vowels in two conditions that included lexical information, and one condition in which the vowel portions of the recorded words were presented in isolation, preventing listener reference to the vowels’ lexical context. Results indicate an interaction between lexical familiarity for speakers, speaking prompt type, and intelligibility scores. Lexical frequency for listeners did not impact intelligibility scores.

Cochlea-scaled entropy, not consonants, vowels, or time, best predicts speech intelligibility

Speech sounds are traditionally divided into consonants and vowels. When only vowels or only consonants are replaced by noise, listeners are more accurate understanding sentences in which consonants are replaced but vowels remain. From such data, vowels have been suggested to be more important for understanding sentences; however, such conclusions are mitigated by the fact that replaced consonant segments were roughly one-third shorter than vowels. We report two experiments that demonstrate listener performance to be better predicted by simple psychoacoustic measures of cochlea-scaled spectral change across time. First, listeners identified sentences in which portions of consonants (C), vowels (V), CV transitions, or VC transitions were replaced by noise. Relative intelligibility was not well accounted for on the basis of Cs, Vs, or their transitions. In a second experiment, distinctions between Cs and Vs were abandoned. Instead, portions of sentences were replaced on the basis of cochlea-scaled spectral entropy (CSE). Sentence segments having relatively high, medium, or low entropy were replaced with noise. Intelligibility decreased linearly as the amount of replaced CSE increased. Duration of signal replaced and proportion of consonants/vowels replaced fail to account for listener data. CSE corresponds closely with the linguistic construct of sonority (or vowel-likeness) that is useful for describing phonological systematicity, especially syllable composition. Results challenge traditional distinctions between consonants and vowels. Speech intelligibility is better predicted by nonlinguistic sensory measures of uncertainty (potential information) than by orthodox physical acoustic measures or linguistic constructs.

Vowel Intelligibility in Chinese

Conventional wisdom states that, since the average amplitude of vowel articulation significantly exceeds that for consonants, an assessment of spoken intelligibility in obscuring noise should primarily be limited by consonant confusion. Furthermore, in both English and Chinese, consonant discrimination is considered to be more important to overall intelligibility than that of vowels. In the unbounded case, the assumption that vowel confusion is less important than consonant confusion may well be true; however, at least two situations exist where the influence of vowel confusion may be greater. The first is where vocabulary-specific restrictions confine the structure of a particular spoken word to alternatives differing primarily in their vowel. The second is the prevalence of non-additive white Gaussian noise (AWGN) interference, particularly impulsive noise which obscures only the vowel portion of a word, and similarly is present as a nonlinear effect of many time-sliced processing algorithms. This paper explores the issue of vowel intelligibility for spoken Chinese, where the confusion characteristics are complicated through the influence of lexical tone carried by the vowel in consonant-vowel-consonant (CVC) structure utterances. Experimental evidence from multilistener intelligibility testing are presented to build toward an understanding of the characteristics of Mandarin Chinese vowel confusion in the presence of AWGN. Results are also isolated by carrier word consonants and in terms of the lexical tone overlaid upon tested vowels. In particular, several factors relating to issues such as vowel length, tone combination and the crucial influence of the /a/ (IPA ) phone are revealed.