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The vocal tract model of placement: II. Acoustic aspects.

The technique of "placing" the voice in the throat, head, or elsewhere is used in training singers of operatic quality and in vocal rehabilitation. A vocal tract model of placement has been shown to have perceptual validity (Nichols and Shellenberger, 1985). This study tested its acoustic validity. Line spectra of vowels at different vocal placements were analyzed. We found that Formant 2 reflected changes in vocal placement for both male and female speakers.

Humans

An evaluation of residue features as correlates of voice disorders.

Two experiments were conducted to assess the correlations of residue features with some perceptual properties of voice disorders. First, 90 samples of the vowel /a/ produced by patients with various vocal pathologies were analyzed to obtain the residue features, and severity judgments of these vowel samples were obtained. The results of linear multiple regression analysis indicated that the features were highly correlated with the severity ratings. Second, an attempt was made to correlate the residue features with voice qualities. The features were calculated for the vowel /a/ produced by patients with vocal nodules, vocal fold paralysis, and vocal polyps and by normal talkers. Each vowel sample was rated on ten scales of voice quality. The results revealed high correlations among the quality scales so that discrete subject groups could not be formed. Thus, residue features may be useful in assessing the degree of vocal impairment, but their use as correlates of voice quality must await further research.

Adolescent

Episodic reactive dysphonia: a case study.

This case study exemplifies successful diagnosis through stroboscopic fiberoptic examination, illustrates the critical importance of a careful case history, and demonstrates potential hazards of supposedly benign environmental substances for hypersensitive individuals.

Adult

Phonological space in the speech of the hearing impaired.

The vowels /a/, /i/, and /u/ form the extreme points of vowel triangle in Kannada language. First and second formant frequencies of these vowels were measured to determine the phonological space in the speech of the 30 deaf subjects and 30 normally hearing subjects. The phonological space was found to be reduced in the speech of the hearing-impaired subjects, and the reduction was primarily due to the lowering of the second formant of the vowel /i/. Therapeutic implications have been drawn.

Adolescent

Stability in phonational frequency range.

The purpose of the present study was to investigate the stability of total phonational frequency range, and the stability of the elements from which it is calculated--lowest fundamental frequency and highest fundamental frequency--both within a single day and over a prolonged period. Twenty adult subjects were instructed to produce vowel vocalizations at the extremes of their frequency ranges. Lowest and highest frequencies were converted to semitones, and total range in semitones was calculated. Data were collected three times per day for two days 1-2 months apart. Results revealed that for the average subject, all measures varied by at least several semitones. Further research is needed in order to determine the sources of this intrasubject variability before these measures can be applied to clinical populations.

Adult

Timing in speech: a review of Sanskrit literature and its verification.

The concept of timing in speech as held by the ancient Sanskrit Scholars is described. This has been verified by spectrographically analyzing 109 Sanskrit sentences as spoken by ten Sanskrit speakers. The results seem to partly support the notion of Sanskrit grammarians in that their concept regarding the vowel durations gain support from this study. The information obtained from this study and such reviews could be of great importance in the understanding of human speech production and perception.

Female

A preliminary comparison of flat affect schizophrenics and brain-damaged patients on measures of affective processing.

Flat affect is a major component of schizophrenia and is often also seen in neurological disorders. A preliminary set of comparisons were conducted to delineate neuropsychological mechanisms underlying flat affect in schizophrenia, and new measures are described for the assessment of affective deficits in clinical populations. Subjects were schizophrenic with flat affect (SZs), right brain-damaged (RBD), Parkinson's Disease (PDs), and normal control (NC) right-handed adults. Subjects were administered affective measures of expression and perception in both facial and vocal channels. For both perceptual and expressive tasks the SZs performed significantly less accurately than the NCs and the PDs but did not differ from the RBDs. This was the case for both face and voice. This finding lends support to the speculation that right hemisphere mechanisms, especially cortical ones, may be compromised among schizophrenics with flat affect.

Adult

A fundamental frequency investigation of children ages 6-10 years old.

The fundamental frequency characteristics of 30 children between the ages of 6 and 10 years were investigated in a variety of speech tasks. The results indicated that average fundamental frequency across tasks for the boys is approximately 262 Hz, and for girls approximately 281 Hz. Statistical analysis indicated that there was no significant difference in the fundamental frequency of boys and girls in this age range. High vowels were found to have higher fundamental frequency values than low vowels. Sustained vowels had higher fundamental frequency values than either spontaneous speech or reading for both groups of speakers. The results of this investigation are discussed in terms of maturational processes, and in comparison to corresponding adult information.

Child

Harsh voice: vocal effort perceptual ratings and spectral noise levels of hearing-impaired children.

This study investigated the relationship between spectral noise levels and ratings of perceived vocal effort in the voices of severely to profoundly hearing-impaired children as compared to normal-hearing children, aged 6-11. Spectral noise levels served as an index of the inharmonic (noise) components present from 100 to 2500 Hz for sustained vowels. A nine-point perceptual rating scale was devised as the subjective measure of vocal effort. The severely to profoundly hearing-impaired children could be differentiated on the basis of significantly higher ratings for perceived vocal effort in addition to higher physical measurements of spectral noise levels. Tentative therapeutic implications are discussed.

Child

Dysarthria of motor neuron disease: clinician judgments of severity.

Motor Neuron Disease (MND) is a terminal, demyelinating disease affecting upper- and lower-motor neurons and producing muscular weakness resulting in a characteristic spastic-flaccid dysarthria of speech. The present study investigates the relationship between the temporal-acoustic parameters of the speech of 15 individuals with MND as they relate to the progression of the disease and clinicians' judgments of dysarthria severity. When temporal-acoustic parameters are used to predict the progression of MND, it becomes apparent that victims provide compensatory gestures to mark voicing distinctions. When the same acoustic parameters are used to predict clinician judgments of severity, it is found that clinicians tend to use the same temporal cues that mark actual disease progression. Differences between the two sets of predictions relate to the linguistic systems of both speaker and judge, and the implications of this are discussed.

Adult

Systematic sound preference in phonological disorders: a case study.

Systematic sound preference, where a group of sounds with the same manner of articulation is represented by one or two sounds in the production, is one of the characteristics of children with phonological disorders. This article examines the hypotheses advanced by Weiner (1981) for the phenomenon in the light of the data from a 7-year old Portuguese speaking child. The findings support some of the hypotheses, while providing counter evidence for one of them. They also point to the importance of word position and stress patterns in the systematicity of systematic sound preference.

Articulation Disorders

Toward implementation of a flexible hearing aid measurement system.

An evaluation of a computerized hearing aid measurement system was performed with input and output compression hearing aids stimulated using high-quality audio equipment. The results of the computer measurements were compared to those from a manual technique using conventional laboratory instrumentation. The results from the computerized and manual methods matched very closely. However, the computer system was found to be considerably more flexible than conventional instrumentation and was much easier to use.

Equipment Design

Phonatory and phonetic characteristics of prelinguistic vocal development in cri du chat syndrome.

A longitudinal case study of a child with cri du chat syndrome was undertaken to provide descriptive data on early phonatory and phonetic development in comfort state vocalizations. Vocal samples collected when the child was between 8 and 26 months of age were analyzed using perceptual and acoustic methods. Results indicated that the high vocal fundamental frequently documented in cries of infants with cri du chat syndrome was also a characteristic of comfort state vocalizations of this child. An analysis of intonation patterns indicated there was a predominance of falling intonation contours and limited interutterance variation of fundamental frequency. Phonetic development was quite delayed, with major acquisitions in babbling showing marked delay relative to chronological age. Acquisition of the first spoken word had not occurred by the age of twenty-six months. Results suggest that significant cognitive and/or motor delays may have an influence on the integrity of early vocal development, which calls into question the notion that babbling development proceeds relatively independently of other developmental domains.

Child, Preschool

The use of an autochromatic tuner for the measurement of vocal fundamental frequency.

Comparative measures of vocal fundamental frequency were made with three different instruments, the Visi-Pitch. FLORIDA 1, and a Korg Autochromatic Tuner. The purpose of these measures was to determine whether an autochromatic tuner, a relatively inexpensive device designed to assist musicians in fast-tuning their instruments, would provide a valid and reliable measure of vocal fundamental frequency. Subjects for this study included 15 males and 15 females. They were recorded while sustaining vowels, reading a phonetically balanced passage, and singing to their lowest and highest pitch levels. Spearman's Rho correlations indicated that measures taken with the autochromatic tuner significantly correlated with measures taken with the other instruments. Results indicate that the use of an autochromatic tuner to measure vocal fundamental frequency is an effective and inexpensive alternative to other methods for clinical purposes.

Adult

Production of linguistic prosody by normal and speech-disordered children.

Features associated with the production of linguistic prosody were investigated in seven speech-disordered children and seven children with age-appropriate speech abilities. All subjects were required to imitate 40 stimuli containing either a rising or falling terminal contour. Half of the stimuli were meaningful sentences whereas the other half were nonmeaningful repetitions of a single syllable. Both types of stimuli were produced with the same suprasegmental features. Acoustic analyses were used to measure a variety of prosodic features associated with the intonation (Fo) and timing characteristics of the imitated stimuli. The primary differences between the two groups of children focused on timing characteristics of the imitated responses. Differences in Fo characteristics also were identified, but in some instances interacted with timing deviations. Results are discussed in reference to potential physiologic and/or linguistic processes that might contribute to dysprosody in speech-disordered children.

Child

Intonation and speech rate in dysarthric speech.

Ten dysarthric speakers of various etiologies, type, and severity were compared to age-matched and gender-matched nondysarthric speakers on 40 short sentences. These sentences were presented in both declarative and interrogative versions. Measures of (1) mean intonation difference (average difference in fundamental frequency between the last syllables of interrogative and declarative sentences) and (2) speech rate were obtained using the IBM Speech Viewer system. Analyses of variance were performed on the resulting measures with subject group, sentence type, and sentence sets as independent variables. Results indicate that (1) intonation values are significantly reduced in the dysarthric group as compared to those for the nondysarthric group; (2) rate varies as a function of subject group, sentence type, and sentence set. Moreover, intonation varies with severity of dysarthria, but not speech rate. These findings concur with the notion that dysarthria is a deficit in performance rather than in competence. The results are also discussed in reference to "breath-group" theory for intonation (Lieberman, 1967).

Brain Damage, Chronic

Age-related differences in speech variability among women.

The purpose of this study was to examine the differences in variability of several measures of the speech produced by two groups of women, one aged 20-35 years and one aged 75 years and over. The subjects read the first paragraph of the "Rainbow Passage," sustained vowels at three loudness levels, and repeated a carrier phrase in which a series of 18 syllables were embedded. Data were gathered on intraoral pressure (PIO), vocal intensity, speaking fundamental frequency (SFF), voice onset time (VOT), and phoneme duration. The F-max test and ANOVA statistics revealed that the older women exhibited greater within-subject variability than the younger women for PIO, SFF, VOT, and consonant duration. These factors required more precise temporal, respiratory, phonatory, or articulatory adjustments than did the vocal intensity tasks or vowel duration. The variability differences found in this study may reflect individual patterns of acoustic and physiologic change in the speech produced by older women.

Adult

Infants' perception of timbre: classification of complex tones by spectral structure.

Infants 7 to 8.5 months of age were tested for their discrimination of timbre or sound quality differences in the context of variable exemplars. They were familiarized with a set of complex tones with specified spectral structure; members of the set varied in fundamental frequency, intensity, or duration. Infants were then tested for their detection of tones that contrasted in spectral structure but were similar in other respects. They successfully differentiated the two spectral structures in the context of these variations, indicating that they can classify tonal stimuli on the basis of timbre. When the stimuli were organized into arbitrary categories, infants were unable to differentiate these categories, indicating that their performance with nonarbitrary categories was not attributable to memorization of the familiarized set.

Female