Vocal changes in stutterers and nonstutterers during high- and low-pitched speech

This study was conducted to provide an indirect test of Wingate's “modified vocalization” hypothesis. In this formulation, the improved fluency that stutterers experience in various novel conditions is attributed to changes in the key correlates of stress, namely, fundamental frequency, vocal SPL, and rate.Normal speakers and stutterers read aloud in an habitual condition following instructions to read at higher- and lower-than-normal pitches. Objective measures were taken of subjects' fundamental frequency, fundamental frequency deviation, vocal SPL, and fluent reading rate. Disfluences were also counted. Findings showed that both stutterers and normals altered several features of voicing from the habitual to the two experimental conditions. Significant condition main effects emerged for fundamental frequency deviation, vocal SPL, fluent reading rate, and disfluency. The only meaningful between-group difference noted showed that the stutterers were more disfluent than the normals across all conditions. Results were interpreted as supporting Wingate's “modified vocalization” position and were discussed relative to how the vocal changes observed might act to promote fluency.     

Vocal changes in stutterers and nonstutterers when speaking to children

Within the last few years, considerable attention has been devoted to the possibility that the amelioration of stuttering in many novel speaking conditions is a function of vocal changes with or without accompanying modifications in prosodic expression. These formulations have made reference primarily to conditions in which stutterers were induced into one or another novel speech pattern by an external stimulus such as masking noise, a rhythmic cue, or by instructions to sing, or read in unison with another speaker. In contrast, far less attention has been paid to other ameliorative conditions that lack a novel external stimulus or special instructions that direct the stutterer to speak in some unique manner. Speaking or reading to a child is an example of this latter type of condition. The present study was conducted to see if nine adult stutterers and a matched group of nonstutterers would evince vocal changes as they read aloud to another adult, a child, and a child and adult together. There was also a fourth control condition wherein the subjects read to one of the experimenters. Dependent measures of disfluency and stuttering, fundamental frequency, fundamental frequency deviation, fluent reading rate, and peak vocal sound pressure level were made and treated statistically. The major findings of this study indicated that, relative to the control condition, both subject groups exhibited several vocal changes when reading to a child alone and to a child and adult together. In addition, the stutterers experienced a reduction in disfluency, but only when reading to the child alone. The normal speakers exhibited too few disfluencies in the control condition for any meaningful change to occur in that dependent variable. The fact that the stutterers evinced vocal changes in both experimental conditions but a significant drop in disfluency in just one bears importantly on hypotheses that emphasize vocal changes in conditions that ameliorate stuttering.     

Rate changes in the speech of stutterers after therapy

The fluent speaking rate of nine adult male stutterers was compared before and after stuttering intervention. The subjects, ranging in age from 18 to 37 yr (mean, 25 yr, 3 mo), exhibited mild to severe stuttering prior to treatment. The only rate reduction strategy taught to subjects during intervention was to slow the first phoneme or syllable of sentences spoken. In addition, however, subjects significantly reduced their overall rate as determined by measurements made of their fluent speech at the middle of sentences, as well as overall sentence durations (excepting the first word of utterances). The data from this investigation are interpreted relative to the facilitation/simplification hypothesis.     

A study of language functioning in Alzheimer patients

Language functioning in Alzheimer's disease is reviewed and the performance of 25 Alzheimer patients on a standard battery is reported. All these hospitalized patients were aphasic to some degree. As a group, they differed from normals on all language variables, and from stroke patients in terms of higher fluency and lower comprehension. Spontaneous speech showed high incidence of circumlocutions and semantic jargon, but no phonemic paraphasias or target approximations. Syllabic perseverations, shouting, inappropriate laughter, and mutism were late-appearing features. Transcortical Sensory, and Wernicke's aphasias were frequent, but Broca's and Transcortical Motor aphasias notably absent. Extent of language impairment correlated with current length of hospitalization but not age. Reading, writing, and performance scores except praxis, were lower than oral language scores. Findings were discussed in relation to previous results, methodology, and language organization in the brain.     

Reaction-time measures of stutterers and nonstutterers

Ten adult male stutterers and ten adult male nonstutterers participated in six reaction-time tasks designed to measure manual, acoustic, and laryngeal-region response latencies. The analysis revealed statistically significant differences between the groups for the acoustic data only. The results indicated that acoustic reaction-time differences are not accounted for by the speed of the general laryngeal response.     

A comparison of syntax in young stutterers and nonstutterers

This study compares the syntactic structure of the spontaneous speech of a small group of stutterers and nonstutterers, using a method of constituent analysis. Speech samples were taped during play sessions with subjects, and the tapes were then transcribed and analyzed according to preselected constituent criteria. The stutterers were in the early stages of stuttering and had been diagnosed as stutterers by experienced clinicians. The method of analysis proved to be highly reliable. Differences were found in the number of complete clauses, the number of complex sentences, and in clause types between the two groups.     

Vocal changes in stutterers and nonstutterers during monotoned speech

For years, reports have circulated that stutterers experience marked decrements in their stuttering when they speak or read in monotone. Wingate has suggested that the ameliorative effects of various novel speaking conditions on stuttering can be attributed to modifications in vocalization induced by such conditions. The present study was conducted to see whether this explanation would extend to monotoned speech as well. Ten teenage and adult stutterers and 10 normal speakers were tested in control and monotone reading conditions. Dependent measures were the frequencies of disfluency and stuttering, fundamental frequency, fundamental frequency standard deviation, vocal SPL, vocal SPL standard deviation, and fluent reading rate. Only within-group statistical comparisons were made, because members of the two groups could not be matched pairwise along critical vocal parameters. The major findings of this study indicated that across the two conditions, both groups significantly reduced their fundamental frequency, fundamental frequency standard deviation, vocal SPL and vocal SPL standard deviation. Only the stutterers exhibited a significant decrement in disfluency and stuttering. The normals did not evince enough disfluency in the control condition for a reduction to occur during monotoning. Neither group effected a reduction in fluent reading rates. These and other findings and interpretations are discussed relative to Wingate's modified vocalization hypothesis.     

Voice onset time in aphasia: Thai. I. Perception

This study investigated left brain-damaged aphasic and right brain-damaged non-aphasic patients' ability to label synthetic speech continua differing in voice onset time (VOT) at three places of articulation. The language chosen for investigation was Thai, which exhibits 3 contrasting labial and apical stop categories (voiced, voiceless unaspirated, voiceless aspirated) and 2 contrasting velar stop categories (voiceless unaspirated, voiceless aspirated). Results of the labelling task indicated an impairment in VOT perception at all three places of articulation across clinical types of aphasia. Normal performance by the right brain-damaged patient indicated that deficits in VOT perception can be attributed to pathology specific to the language-dominant hemisphere. No relation was found between the aphasic patient's level of auditory language comprehension and his performance on the VOT perception task. It is suggested that the aphasics' impairment reflects a deficit in phonological processing at the linguistic level.     

Rate reduction strategies used by normally fluent and stuttering children and adults

Speech rate can be reduced by prolonging the duration of phonetic units, by pausing between words, or through a combination of these approaches. Child and adult normally fluent speakers and stutterers were tested in basal and modified speaking rate conditions. Subjects' utterances in both conditions were converted to spectrographic displays so that measures of phonetic and pause durations could be made. Comparisons of these measures across conditions revealed that all four groups of subjects spontaneously extended pause and phonetic durations, the former more than the latter, when instructed to voluntarily reduce speech rate.     

Implications of evaluating and intervening with incipient stutterers

A study was conducted to investigate the factors involved in the recovery from incipient stuttering without therapeutic intervention. Fifteen subjects were seen on two occasions, once for an initial evaluation after the reported onset of stuttering, and for a second evaluation to determine if they had recovered or become chronic stutterers. Within the constraints of a small sample, several findings are presented: (1) 80% of the children recovered spontaneously from stuttering, (2) subjects who exhibited more types and frequencies of disfluencies upon onset had a poorer prognosis for recovery, (3) the age of onset, if under 4 years, had little bearing on recovery, and (4) children who were seen professionally soon after disfluency onset had the greatest prognosis for recovery. Possible implications of these results are discussed.     

Confrontation naming impairment in dementia

In tone languages pitch variations (tones) serve to distinguish the lexical meanings of words. This study was conducted to examine the extent and nature of impairment in the perception of tones by aphasic patients who were monolingual speakers of Thai, a tone language which has five contrastive tones (mid, low, falling, high, rising). Six subjects participated in the study: two Broca aphasics, one transcortical motor aphasic, one conduction aphasic, one right brain-damaged nonaphasic, and one normal control. Three sets of stimuli (two real-speech, one synthetic-speech) were presented for identification, each set containing five Thai words minimally distinguished by tone. Results of the perception tests indicated that the performance of all four left brain-damaged aphasics differed significantly from that of the normal control, while the performance of the right brain-damaged nonaphasic did not. The normal performance of the right brain-damaged nonaphasic patient on this tone identification task suggests that deficits in the perception of tone exhibited by left brain-damaged patients can be attributed specifically to pathology in the language dominant hemisphere rather than to a general brain-damage effect. No difference in performance among the left brain-damaged patients could be attributed to a specific type of aphasic syndrome. The pattern of tonal confusions of the aphasics in comparison to that of normals suggests that their deficit is primarily quantitative rather than qualitative. Although two (mid, low) of the five tones accounted for a large percentage of the aphasics' errors, no uniform rank order of tones in terms of identifiability could be established across aphasic subjects, which suggests that their deficit is general to all five tones rather than selective to individual tones.     

Prosodic disturbance in aphasia: Vowel length in Thai

The aim of this study is to determine to what extent a phonologically contrastive function of the prosodic feature of length is resistant to impairment in aphasia. The language chosen for investigation is Thai, a language which contrasts short and long vowels. Subjects included two Broca aphasics, one transcortical motor aphasic, one Wernicke aphasic, one conduction aphasic, one nonaphasic right-brain-damaged patient, one nonaphasic cerebellar dysarthric patient, and five normal controls. The subjects read a list of words containing short and long vowels. Vowel durations were measured from spectrograms. The results showed that the timing of vowel duration for signaling the contrast between short and long vowels remains relatively intact in nonfluent as well as fluent aphasic patients. These data are brought to bear on issues concerning the specialization of the left hemisphere for temporal processing, the contribution of the right hemisphere to the processing of nonaffective components of prosody, the nature of prosodic disturbance in Broca's aphasia and cerebellar dysarthria, and the separate disruption of prosodic features.     

A comparison of LRT and VOT values between stutterers and nonstutterers

The experiment reported here found no significant group differences in laryngeal reaction time (LRT) and voice onset time (VOT) values. Rank-order correlations between the stutterers' LRT and VOT values were also nonsignificant. A model of the LRT paradigm is presented that (1) allows for systematic assessment of factors possibly contributing to the failure to replicate the often reported LRT group difference, and (2) is useful in examining the relationship between the LRT experimental condition and normal speaking conditions. We argue that two factors were particularly critical to our results. First, simple reaction time procedures included (1) a warning signal that preceded a response signal by a variable 1–3-sec foreperiod, and (2) a single response. We argue that foreperiod durations exceeded the stutterers' speech posture time for a known response. Second, the stuttering severity rating of our experimental group was less severe than ratings in other experiments.     

Resistance to satiation: Reinforcing effects of food and eating under satiation

It has been shown previously that rats which have learned a response when hungry will continue to make that response when tested satiated, a phenomenon labeled resistance to satiation. Here we showed that rats which were previously trained hungry will learn a new response for the opportunity to consume pellets in a new situation when tested satiated. In four experiments various groups received each of the components of the training given when rats learn an instrumental response when hungry. Rats were placed in the goalbox of a straight alley and given food pellets when hungry or were hungry only in their home cages prior to running a straight alley in the satiated test in Experiment 1. In Experiments 2, 3, and 4 learning of a differential conditioning problem for pellets in S+ (nonreward in S?) was measured in the satiated test. Groups given pellets in their home cages when hungry with or without alley exposure learned to run more rapidly in S+ than in S? in the satiated test phase. The tendency to eat pellets in the apparatus and the reinforcing effect of eating the pellets was larger for rats which ate the pellets when hungry in their home cage than for rats which ate the pellets when satiated in their home cage. Being hungry in the home cage with no pellets was not sufficient to produce eating or running for pellets in the satiated test, indicating that any inherent reinforcing effect of the pellets is not sufficient to produce eating or running, and that incomplete satiation cannot account for the learning. These data indicate that a reinforcing effect of eating pellets under satiation is an important determiner of resistance to satiation.     

Case study of a Thai conduction aphasic

A case study of a 55-year-old nonfamilial left-handed monolingual Thai patient with clinical and pathoanatomic evidence of major infarction in the left temporoparietal region is presented. He was studied at 9 years poststroke with a Thai adaptation of the Boston Diagnostic Aphasia Exam and supplementary tests. His language characteristics included fluent spontaneous speech, near-normal auditory language comprehension, and poor repetition, leading to a diagnosis of conduction aphasia. In regard to this aphasic syndrome, issues concerning classification, neuroanatomic correlates, and underlying neuropsychological mechanisms are addressed. The nature of his grammatical disturbance is examined critically in light of the notion of “information load.”     

Voice onset time in aphasia: Thai II. Production

The aim of this study was to investigate voice onset time (VOT) production in homorganic word-initial stops in Thai in order to explore the nature of speech production deficits across clinical varieties of aphasia. Thai exhibits a three-category distinction in bilabial (/b,p,ph/) and alveolar (/d,t,t,h/) stops, and a two-category distinction in velar (/k,kh/) stops. Subjects included three Broca asphasics, one transcortical motor asphasic, two global asphasics, one conduction aphasic, one Wernicke aphasic, one nonaphasic dysarthric patient, one right-brain-damaged patient, and five normal controls. Test stimuli consisted of eight monosyllabic real words. The results of VOT measurements indicated that Broca and global asphasics exhibited a more severe production disorder than Wernicke, conduction, or transcortical motor asphasics. The right-brain-damaged patient showed no impairment in VOT production. Comparisons are drawn to earlier studies of VOT production in aphasia in two-category languages. Issues concerning the underlying basis of the production deficit for nonfluent aphasics, fluent aphasics, and nonaphasic dysarthrics as well as the relation between perception and production of VOT are discussed.     

The effects of prior task experience in the modeling situation

An investigation was made into the effects of observers' previous experience with the experimental task on acquisition and subsequent performance of modeled task behavior. The task was socially neutral and the subjects were second grade boys and girls. Recall of modeled actions increased with prior experience, indicating greater acquisition. This finding supports Bandura's (1973) assertion that task familiarity may enhance attentiveness to the model. Contrary to previous research, performance of imitation did not decrease with experience. The present performance results are possibly due to the ambiguity of the preexperience and novelty of the experimental task.     

Manual reaction time to linguistic stimuli in child stutterers and nonstutterers

Ten stuttering and ten nonstuttering children, ages 4–8 yr, served as subjects for a motor reaction task to simple and complex linguistic stimuli. The subjects reacted by pressing one of four panels on a touch-sensitive board that depicted the appropriate semantic relationship in response to 30 simple and complex linguistic stimuli. There was a significant increase in the reaction time of both groups with increasing linguistic complexity. No significant differences were found in the reaction time between the two groups, nor in the interaction between group and complexity. Implications regarding linguistic processing are discussed, and an “overload” hypothesis of stuttering is dispelled. It is concluded that stutterers and nonstutterers in this study did not differ in their reaction time nor in their processing time of linguistic material.