Shawn L. Nissen

Articulatory changes in muscle tension dysphonia: evidence of vowel space expansion following manual circumlaryngeal therapy.

UNLABELLED In a preliminary study, we documented significant changes in formant transitions associated with successful manual circumlaryngeal treatment (MCT) of muscle tension dysphonia (MTD), suggesting improvement in speech articulation. The present study explores further the effects of MTD on vowel articulation by means of additional vowel acoustic measures. Pre- and post-treatment audio recordings of 111 women with MTD were analyzed acoustically using two measures: vowel space area (VSA) and vowel articulation index (VAI), constructed using the first (F1) and second (F2) formants of 4 point vowels/ a, i, ae, u/, extracted from eight words within a standard reading passage. Pairwise t-tests revealed significant increases in both VSA and VAI, confirming that successful treatment of MTD is associated with vowel space expansion. Although MTD is considered a voice disorder, its treatment with MCT appears to positively affect vocal tract dynamics. While the precise mechanism underlying vowel space expansion remains unknown, improvements may be related to lowering of the larynx, expanding oropharyngeal space, and improving articulatory movements. LEARNING OUTCOMES The reader will be able to: (1) describe possible articulatory changes associated with successful treatment of muscle tension dysphonia; (2) describe two acoustic methods to assess vowel centralization and decentralization, and; (3) understand the basis for viewing muscle tension dysphonia as a disorder not solely confined to the larynx.

Acoustic and Spectral Characteristics of Young Children's Fricative Productions: A Developmental Perspective

Scientists have made great strides toward understanding the mechanisms of speech production and perception. However, the complex relationships between the acoustic structures of speech and the resulting psychological percepts have yet to be fully and adequately explained, especially in speech produced by younger children. Thus, this study examined the acoustic structure of voiceless fricatives (/f, theta, s, S/) produced by adults and typically developing children from 3 to 6 years of age in terms of multiple acoustic parameters (durations, normalized amplitude, spectral slope, and spectral moments). It was found that the acoustic parameters of spectral slope and variance (commonly excluded from previous studies of child speech) were important acoustic parameters in the differentiation and classification of the voiceless fricatives, with spectral variance being the only measure to separate all four places of articulation. It was further shown that the sibilant contrast between /s/ and /S/ was less distinguished in children than adults, characterized by a dramatic change in several spectral parameters at approximately five years of age. Discriminant analysis revealed evidence that classification models based on adult data were sensitive to these spectral differences in the five-year-old age group.

Psychometrically equivalent mandarin bisyllabic speech discrimination materials spoken by male and female talkers

The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Mandarin bisyllabic word lists for use in measurement of speech discrimination. Familiar bisyllabic words were digitally recorded by male and female talkers of Standard Mandarin. Percentage of correct word recognition was measured for each word at ten intensity levels (−5 to 40 dB HL) in 5 dB increments using 20 normally hearing subjects. Using logistic regression, 200 words with the steepest logistic regression slopes were included in four psychometrically equivalent word lists of 50 words each, and eight half-lists of 25 words each. To increase auditory homogeneity of the lists, the intensity of words in each list was digitally adjusted so that the threshold of each list was equal to the midpoint between the mean thresholds of the male and female half-lists. Digital recordings of the psychometrically equivalent word recognition lists are available on compact disc.

Psychometrically equivalent trisyllabic words for speech reception threshold testing in Mandarin.

The aim of this investigation was to develop, digitally record, evaluate, and equate Mandarin trisyllabic words, which could then be used to measure the SRT. A selection of 90 frequently utilized trisyllabic words were digitally recorded by male and female talkers of Standard Mandarin and presented to 20 normally hearing subjects at 13 intensity levels (−10 to 14 dB HL) in 2 dB increments. Using logistic regression, psychometric functions were then calculated for all words. Twenty-four trisyllabic words with steep psychometric function slopes were selected, and their intensities were digitally adjusted to match the mean subject PTA (3.0 dB HL). The mean slopes for the 24 selected male and female trisyllabic Mandarin Chinese words were 11.3%/dB and 12.1%/dB, respectively. Thus we developed a list of words which were homogeneous with respect to audibility and slope. Digital recordings of the psychometrically equivalent trisyllabic words are available on compact disc.

Psychometrically equivalent Russian speech audiometry materials by male and female talkers

Despite the large number of individuals who speak Russian, only a limited number of high-quality speech audiometry materials are available in a standard dialect of Russian. Thus, the purpose of this study was to develop and evaluate speech audiometry materials that can be used to measure word recognition and SRT testing in quiet for native speakers of Russian. Familiar monosyllabic and bisyllabic words were digitally recorded by male and female talkers of Russian and subsequently evaluated by native listeners. Using logistic regression, psychometric functions were then calculated for all words. Selected monosyllabic words were digitally adjusted to create word recognition lists which are relatively homogeneous with respect to audibility and psychometric slope. Speech reception threshold materials were developed by selecting twenty-five bisyllabic words with relatively steep psychometric function slopes (12.1%/dB and 9.9 %/dB) and digitally equating their intensity to match the mean PTA of the native listeners. Digital recordings of the resulting psychometrically equivalent speech audiometry materials are available on compact disc.

Bidirectional Interference between Speech and Postural Stability in Individuals with Parkinson's Disease

Because people frequently talk while engaged in other activities, and because Parkinsons disease (PD) is known to diminish multi-tasking performance, this study examined dual task interference between speaking and postural stability in nine individuals with PD, seven age-matched, and 10 healthy young controls. Participants repeated a target utterance and performed a rise to toes task in both single and dual task conditions. Diphthong transitions were measured from audio recordings and postural variables reflecting planning, coordination, and stability were derived from a multi-camera motion capture system and force plate recordings. Thus, sensitive measures of both speech and postural control were obtained. The group with PD performed more poorly than both control groups for the isolated postural task, but their single task speech measures did not differ from the controls, in spite of listener ratings which indicated mild-to-moderate dysarthria severity. The group with PD showed evidence of bidirectional dual task interference in that there were reduced diphthong extents and slopes along with smaller, slower, and less stable postural movements. These results indicate that concurrent performance of speech and a challenging postural control task impairs speech and postural stability in persons with PD and may result in greater risk during daily activities.

Measuring tongue movements during speech: Adaptation of a magnetic jaw-tracking system

The purpose of the present investigation was to determine whether measurements of tongue movement during speech could be obtained with an electronic device originally designed to record jaw movements via a magnetized pellet. The findings indicated that the system allowed basic quantification of tongue movements in a straightforward manner. The primary advantages of this system are that no distracting wires are attached to the pellet, and it is much less costly than other systems used for this purpose. Its main disadvantages are that it is unable to track multiple tongue fleshpoints simultaneously, lacks an anatomically based coordinate system, and the head must remain still during recordings.

First and second language tongue movements in Spanish and Korean bilingual speakers.

A number of previous studies have relied on perceptual judgments or acoustic analysis to examine second language (L2) production. However, few researchers have studied L2 performance by directly tracking the physical movements of the articulators. The purpose of the present study was to investigate intraspeaker differences in native (Korean or Spanish) and L2 (English) production through kinematic indices of tongue activity. This involved measurement of the speed, duration, and distance of tongue movements or strokes during speech. Findings indicated that the speakers had significantly slower stroke speeds and longer movement durations for L2 when compared to their native language (L1), yet no significant differences in stroke distance. The bilingual speakers were found to pause more and speak proportionally less of the time in their L2. Interestingly, those speakers who exhibited greater relative kinematic changes from L1 to L2 were also rated as having a stronger perceived accent.

Development of speech reception threshold materials for speakers of Taiwan Mandarin

The aim of this research was to develop, digitally record, evaluate, and equate speech audiometry materials that can be used to measure the speech reception threshold (SRT) in quiet for native speakers of Taiwan Mandarin. Familiar trisyllabic words were digitally recorded by male and female talkers of Taiwan Mandarin and subsequently evaluated by 20 native listeners with normal hearing at 14 intensity levels (−10 to 16 dB HL) in 2 dB increments. Using logistic regression, psychometric functions were calculated for all words. Twenty-eight words with comparatively steep psychometric functions were selected and digitally adjusted to match the mean subject pure-tone average (5.0 dB HL). This resulted in a list of words that are relatively homogeneous in threshold audibility and psychometric function slope. The mean slopes for the 28 selected male and female trisyllabic Taiwan Mandarin words were 11.3%/dB and 11.7%/dB, respectively.

Acoustic and Spectral Patterns in Young Children's Stop Consonant Productions

The aim of this study was to examine the acoustic and spectral patterns of stop articulation in the speech of pre-pubescent children. A set of voiceless stop consonants, /ptk/, produced by a group of adults and typically developing children 3-5 years of age were examined in terms of multiple acoustic and spectral parameters. Findings indicated that, with the exception of spectral kurtosis, the acoustic and spectral characteristics of the stop productions varied significantly as a function of place of articulation and vowel context. Sex-specific differences in spectral slope, mean, and skewness were found for the 5-year-old and adult speakers. Such differences in adult speakers can be explained in part by variation in vocal tract size across the sex of the speaker; however, vocal tract dimorphism is typically not present in pre-pubescent children. Thus, the findings of this study provide some support that sex-specific differences in the speech patterns of young children may be associated with learned or behavioral factors, such as patterns of obstruent articulation that depend in part on a culturally determined male-female archetype.