James J. Mahshie

Inverse Filtering of Nasalized Vowels Using Synthesized Speech

The present study examines the extent to which increased nasal coupling affects estimates of glottal parameters derived from inverse filtering based on an all-pole assumption of the vocal tract. A series of steady-state tokens for five Swedish vowels were synthesized using the HLsyn quasi-articulatory synthesizer (Sensimetrics, Malden, MA). For each vowel, the parameter controlling the cross-sectional area of the nasal aperture, an, was systematically varied, while the other HLsyn parameters were kept constant. The resultant pressure signal for each utterance was subsequently inverse filtered, and estimates were made of five glottal source parameters (EE, RG, RA, RK, and OQ) derived from fitting the Liljencrants and Fant source model to the inverse filtered signal. The results show that when analyzing nasalized vowels using inverse filtering based on an all-pole assumption of the vocal tract, the RA parameter estimate--a main determinant of the source spectral slope--can be adversely affected by nasal coupling. The errors in our estimates were particularly high for the high vowels: this was true not only for RA, but for all the parameters measured. However, with the exception of the distortion in the RA estimate, the effects were relatively small, regardless of the degree of nasal coupling.

Categorical perception in two pairs of Mandarin tones among bimodal cochlear implanted children

We investigated the categorical perception for two tone-pairs in Mandarin (T1-T2 and T1-T4) by two groups of 4–5 year-old children — normal-hearing (NH) children and hearing-impaired children with bimodal cochlear implants/hearing aids. The perceptual identification tests using two sets of synthetic speech stimuli varying only along F0 continua were administered. Both the hearing and Cochlear Implant (CI) groups showed categorical effects in the two identification tests, but the category boundaries in the CI group were more biased toward T2 (rising tone) or T4 (falling tone) than was observed in the NH group. This finding suggests that the children with CIs are perceptually less sensitive to contour tones with dynamic pitch movements. For the CI group, the categorical effect was slightly stronger than the NH group in perceiving the T1-T4 continuum, but was weaker than the NH group in perceiving the T1-T2 continuum, suggesting that the children with CIs had particular difficulty in perceiving pitch distinction between the level and rising tones.

Auditory Perception and Production of Speech Feature Contrasts by Pediatric Implant Users.

Objective: The aim of the present research is to examine the relations between auditory perception and production of specific speech contrasts by children with cochlear implants (CIs) who received their implants before 3 years of age and to examine the hierarchy of abilities for perception and production for consonant and vowel features. The following features were examined: vowel height, vowel place, consonant place of articulation (front and back), continuance, and consonant voicing. Design: Fifteen children (mean age = 4;0 and range 3;2 to 5;11) with a minimum of 18 months of experience with their implants and no additional known disabilities served as participants. Perception of feature contrasts was assessed using a modification of the Online Imitative Speech Pattern Contrast test, which uses imitation to assess speech feature perception. Production was examined by having the children name a series of pictures containing consonant and vowel segments that reflected contrasts of each feature. Results: For five of the six feature contrasts, production accuracy was higher than perception accuracy. There was also a significant and positive correlation between accuracy of production and auditory perception for each consonant feature. This correlation was not found for vowels, owing largely to the overall high perception and production scores attained on the vowel features. The children perceived vowel feature contrasts more accurately than consonant feature contrasts. On average, the children had lower perception scores for Back Place and Continuance feature contrasts than for Anterior Place and Voicing contrasts. For all features, the median production scores were 100%; the majority of the children were able to accurately and consistently produce the feature contrasts. The mean production scores for features reflect greater score variability for consonant feature production than for vowel features. Back Place of articulation for back consonants and Continuance contrasts appeared to be the most difficult features to produce, as reflected in lower mean production scores for these features. Conclusions: The finding of greater production than auditory perception accuracy for five of the six features examined suggests that the children with CIs were able to produce articulatory contrasts that were not readily perceived through audition alone. Factors that are likely to play a role in the greater production accuracy in addition to audition include the lexical and phonetic properties of the words elicited, a child’s phonological representation of the words and motor abilities, and learning through oro-tactile, visual, proprioceptive, and kinesthetic perception. The differences among the features examined, and between perception and production, point to the clinical importance of evaluating these abilities in children with CIs. The present findings further point to the utility of picture naming to establish a child’s production accuracy, which in turn is necessary if using imitation as a measure of auditory capacity.

Assessing speech perception in children with cochlear implants using a modified hybrid visual habituation procedure.

Objectives: The objectives of this research were to determine whether an adapted version of a Hybrid Visual Habituation procedure could be used to assess speech perception of phonetic and prosodic features of speech (vowel height, lexical stress, and intonation) in individual pre-school-age children who use cochlear implants. Design: Nine children ranging in age from 3;4 to 5;5 participated in this study. Children were prelingually deaf and used cochlear implants and had no other known disabilities. Children received two speech feature tests using an adaptation of a Hybrid Visual Habituation procedure. Results: Seven of the nine children demonstrated perception of at least one speech feature using this procedure using results from a Bayesian linear regression analysis. At least one child demonstrated perception of each speech feature using this assessment procedure. Conclusions: An adapted version of the Hybrid Visual Habituation Procedure with an appropriate statistical analysis provides a way to assess phonetic and prosodicaspects of speech in pre-school-age children who use cochlear implants.

Acoustic and aerodynamic analyses of transgender voice.

Acoustic and aerodynamic data are needed to describe how the vocal mechanism of a transgender person operates to achieve desired gender perception. Early evidence‐based practice for transgender voice therapy was limited to changing vocal pitch—at first aiming for the normative values of the desired gender and more recently aiming for more feasible targets of pitch within a “gender‐neutral range” established by perceptual research. 20 years later, research is discovering that pitch may be a major influence in gender perception, but is almost certainly not the only influence. In this presentation, the physiology of 20 voices (male‐to‐female and female‐to male) will be illuminated by reporting the glottal closure patterns (e.g., electroglottography), patterns of airflow through the vocal mechanism (e.g., subglottal pressure estimated from intraoral pressure and derived glottal airflow), and resonant qualities of the vocal tract (e.g., formants). Preliminary data suggest that transgender values are not equiva...

Lingua‐palatal coarticulation by deaf and normal‐hearing speakers

Recent research suggests that deaf speakers often exhibit context‐dependent changes in speech articulation [for example, Mahshie et al., ASHA 32 (10), 183 (1990)]. However the coarticulatory patterns of deaf speakers are not always comparable to those of normal‐hearing speakers. Furthermore, it is likely that deaf individuals exhibit differences among themselves in both the nature and extent of coarticulation–differences that may affect intelligibility. The purpose of the present study was to examine and compare lingua‐palatal coarticulation evidenced by normal‐hearing speakers and by deaf speakers differing in overall speech intelligibility. Three normal‐hearing subjects, one intelligible deaf subject, and one semi‐intelligible deaf subject produced multiple iterations of bisyllabic and trisyllabic words. Test words contained the lingua‐alveolar target segments /t/ or /n/ followed by either the neutral vowel /schwa/ (e.g., ‘‘tana’’) or the velar consonant /k/ (e.g., ‘‘tancat’’). Palatometric measures wer...

Laboratory and clinical use of the electroglottograph

The electroglottograph is a device that enables monitoring of variations of vocal fold contact by measuring motion induced variations in impedance of neck tissue in the area of the vocal folds. Electroglottography represents one of the few noninvasive methods available for obtaining useful information about the vibratory patterns of the vocal folds. Since its initial description [Fabre, Bull. Acad. Med. (1957)], the electroglottograph has become an increasingly popular clinical and research tool, providing insight into numerous phonatory characteristics including vocal fundamental frequency (f0), the extent of vocal fold abduction during phonation, and alterations in laryngeal height during voicing. The purpose of this video presentation is to describe and demonstrate electroglottography, and to examine its use in the clinic and laboratory. The video will: (1) explain the principle of operation of the electroglottograph; (2) demonstrate setup and use of the device; (3) describe attributes of the electrogl...

Glottal waveform characteristics of deaf speakers

The distinctive voice quality that characterizes many deaf individuals suggests that they use phonatory adjustments for speech production that differ from normal. Little research, however, has been reported that examines the phonatory attributes of deaf individuals. The purpose of the present work was to examine glottal volume velocity waveform characteristics of deaf speakers, and to compare these characteristics to those of normal‐hearing talkers. The oral airflow signals associated with non‐nasalized vowels produced by five deaf and five normal‐hearing subjects were inverse filtered, and the resultant signals examined. In addition to qualitative waveform descriptions, measures were made characterizing cycle‐to‐cycle peak volume velocity, duty cycle characteristics, and amount of unmodulated airflow (do offset of the volume velocity signal). Result thus far reveal systematic differences from normal for some of the deaf speakers, while others, particularly those with voice quality perceived as less aberr...