Effect of threat of shock for being disfluent of fluency of normal speakers.

Each of 20 adult nonstutterers read a 330-word passage six times with a one minute pause between readings. Between the third and fourth reading or the fifth and sixth reading (determined by a table of random numbers) Ss were informed that at the conclusion of the next reading an electric shock would be administered for each instance of disfluency detected by E during that reading. Ss did not become less fluent as a consequence of the experimental condition. Their mean disfluency frequency during the threat-of-shock reading was lower than during the preceding one. Thus, threat of shock for being disfluent may be a condition which differentiates stutterers from nonstutterers since stutterers have been reported to become less fluent under this condition.     

Stutterers' voice initiation times during conditions of novel stimulation

The present experiment examined stutterers' voice initiation times (VITs) during conditions of novel stimulation. The experimenters were interested in determining how VITs varied as a function of pacing and masking. Stutterers were examined in control, pacing, and masking conditions. The results indicated that: (1) stutterers significantly improved their VITs in the pacing condition as compared with the control condition (p = 0.005), (2) stutterers had significantly faster VITs in the pacing condition as compared with the masking condition (p = 0.005), and (3) stutterers improved VITs in the masking condition as compared with the control condition (p = 0.075). These results are discussed in terms of the facilatory nature of novel stimulation in modifying speech-system functioning.     

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.     

The differential effect of three auditory stimuli on the frequency of stuttering behaviors

In view of the frequent clinical use of external auditory stimuli in fluency building programs, the purpose of the present experiment was to compare the effects of rhythmic pacing, delayed auditory feedback, and high intensity masking noise on the frequency of stuttering by dysfluency type. Twelve normal hearing young adult stutterers completed an oral reading (approximately 250 syllables) and conversational speech task (3 min) while listening to the three auditory stimuli and during a control condition presented in random order. The results demonstrated that during oral reading all three auditory stimuli were associated with significant reductions in stuttering frequency. However, during conversational speech, only the metronome produced a significant reduction in total stuttering frequency. Individual dysfluency types were not differentially affected by the three auditory stimuli.     

The effects of pacing and masking on stutterers' and nonstutterers' speech initiation times

The present study was undertaken to determine whether pacing and masking would facilitate improved speech initiation times (SITs) both for stutterers and for nonstutterers. All subjects were tested in control, pacing, and masking conditions. The results showed that both stutterers and nonstutterers (1) improved their SITs during the pacing condition as compared with the control condition (p = 0.01), (2) had slower SITs in the masking condition as compared with the control condition (p = 0.05), and (3) had faster SITs during the pacing as compared with the masking condition (p = 0.01). The SIT between-group findings demonstrated that stutterers were slower than nonstutterers across all SIT conditions (p = 0.08). The discussion of these results centers on the facilatory nature of novel stimulation in modifying speech-system functioning.     

Air flow characteristics of the speech of stutterers and non stutterers

This study involved respirometric measurements of six normals and six stutterers throughout vocal and whispered readings of 12 CVC words. In each condition, dependent variables were peak air flow rates on initial and final consonants, flow duration and flow volume between peaks. The stutterers, both individually and as a group, were almost completely fluent during the readings in both conditions. At the same time, their air flow, duration and volume scores either equalled or exceeded those of the controls. These results are discussed in terms of how air flow and durational features of articulation contribute to fluent speech. Directions for future work are also described.     

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.     

Rate reduction strategies used by stutterers and nonstutterers during high- and low-pitched speech

Groups of child and adult normal speakers and stutterers were tested in an habitual condition and in conditions where they were instructed to read aloud at pitches both higher than and lower than normal. Objective measures were made of subjects' fluent reading rate, and vowel and pause durations across conditions. Disfluencies were also counted. Findings revealed that all four subject groups reduced their frequency of disfluency from the habitual to both experimental conditions. These decrements in disfluency were attended by significant reductions in fluent reading rate. Spectrographic analyses revealed that most subjects, regardless of age and speaker characteristic, affected their rate reduction by extending both vowel and pause durations. These results are compatible with those obtained in recent studies and are discussed.     

The effects of presenting a click in syllable-initial position on the speech of stutterers: Comparison with a metronome click

The speech of ten stutterers, recorded while they were listening to a concurrent metronome click and with a click which was triggered so that it occurred at the beginning of every syllable, was assessed. Speech rate and number of disfluencies were measured in each speaking condition. The results indicated that fewer disfluencies occurred (relative to normal reading performance) when a metronome or syllable-initial click was presented.In a perceptual experiment, a group of normal listeners was presented with samples of each of the stutterers' speech from all three speaking conditions. The listeners were asked to choose that which sounded most natural. The speech recorded from the condition where a click occurred at syllable onset was judged more natural than normal speech or speech recorded while the stutterers heard a metronome click.     

Reading rates of stutterers and nonstutterers during silent and oral reading

The purpose of this study was to investigate the differences between the reading rates of stutterers and nonstutterers during both silent and oral reading of fluently spoken words. Ten adult stutterers and 14 nonstutterers were instructed to read two lists of words over four trials each. The first trial of either the first or the second list was a silent reading trial. All the other trials were oral reading trials. The word lists consisted of nouns with word lengths from two to five syllables. The dependent variables were the silent and oral reading times per word and per syllable. The major findings were that stutterers, as compared to nonstutterers, required longer reading times per word and per syllable during both silent and oral reading. These results indicate that stutterers differ from nonstutterers in the basic processing time for verbal material.     

The Adams and Reis observations revisited

This experiment was designed as a replication of the Adams and Reis (1971, 1974) experiments, which posited a direct relationship between frequency of stuttering and the number of “off-on” laryngeal adjustments during speech. Twenty adult stutterers read two prose passages equivalent in length, word length, and semantic content. The first passage contained a normal distribution of syllable-initial voiced and voiceless consonants whereas the second contained only voiced phonemes. The results demonstrated significantly greater stuttering during reading of the all-voiced passage (P?0.05). These results did not confirm the earlier observations of Adams and Reis and mitigate the hypothesized relationships between stuttering frequency and “off-on” laryngeal adjustments.     

Patterns of regional cerebral blood flow during attempted reading aloud by stutterers both on and off haloperidol medication: Evidence for inadequate left frontal activation during stuttering

Two stutterers, both recent college graduates, were subjected to regional cerebral blood flow measurements while attempting to read aloud. Each one received two measurements, one of which was under the influence of haloperidol, 3 mg daily. Both subjects showed improvement on medication, allowing a stuttering versus essentially no stuttering comparisons for each subject. Both subjects showed higher Broca's area flow in the right compared to the left hemisphere, during stuttering. Both showed higher Wernicke's area flow in the left compared to the right hemisphere, however, during stuttering. During reading aloud without stuttering, however, the Brocas's area flows were reversed, now showing a left hemisphere advantage. The results were interpreted as consistent with H. M. Sussman and P. F. MacNeilage's (1975, Neuropsychologia, 13, 19–26) proposal that stutterers exhibit conventional left cerebral dominance for speech reception, but inadequate left cerebral dominance for speech production.     

Reinforcing fluency in stutterers: An experimental study

Subject-specific periods of fluent reading responses of three adult stutterers were positively reinforced with the presentation of a dime. Subjects were run individually through a sequence of two base rate, two experimental, and two extinction sessions, each session lasting 45 min. Periods of fluent reading responses increased during the experimental condition for each of the three subjects. When the reinforcer was withdrawn during the extinction condition, the frequency of fluent periods showed a decrease. Concomitantly, disfluencies decreased during the experimental condition and they increased during the extinction condition. The clinical implications of fluency manipulation as against disfluency manipulation are discussed.     

Choral reading with filtered speech: effect on stuttering

This study investigated use of choral reading with filtered components of speech and whispered speech on the frequency of stuttering. Three passages read by a normal adult male were lowpass filtered with kneepoint frequencies at 100 Hz (approximate glottal source), 500 Hz (source and first formant), and 1 kHz (source and the first two formants). Along with a whispered passage, a normal passage, and a control condition, these stimuli were used in a repeated-measures design with 12 adult stutterers as they read passages while listening to one of the stimuli. Frequencies of stuttering in each condition were analyzed. The choral speech, the 500-Hz, the 1-kHz, and the whispered speech conditions all decreased the frequency of stuttering while the 100-Hz stimuli did not. It is suggested that articulatory events, chiefly the encoded speech output from the vocal tract, create effective cues and may induce fluent speech in people who stutter.     

Attention and stuttering: Do stutterers think too much about speech?

In this investigation the ability of stutterers and nonstutterers to simultaneously perform speech and nonspeech tasks was compared. Subjects were 10 stutterers and 10 nonstutterers. Two experiments were conducted. In the first, subjects performed a non-attention-demanding gross-motor task while they read aloud. In the second, subjects performed an attention-demanding task (reading comprehension) during speech. Results indicated that there was no significant change in the disfluency values of stutterers during the motor activity or as a result of the reading comprehension task. However, stutterers were found to perform significantly poorer than nonstutterers on the reading comprehension task. This finding was taken as evidence that stutterers devote more attention to speech than do nonstutterers.     

Brainstem auditory electrical response characteristics of stutterers and nonstutterers: A preliminary report

In the present study, eight adult male stutterers and nonstutterers showed no significant latency or amplitude differences in BSERs recorded in response to monaural and binaural clicks. However, significantly greater variance was found in the stutterers' group under the monaural stimulation condition at click rates of 12/sec and 5/sec. Left and right monaural waveforms were subtracted individually from the binaural waveform. The resultant binaural interaction difference traces were examined to determine auditory tract preference for binaural stimulation. While some subjects from both groups showed no auditory tract preference, it was found that the significant variance between groups for wave V latency was attributable to the subset of stutterers without auditory tract preference. This finding is interpreted as evidence of neurological differences in stutterers' auditory processing at the brainstem level.     

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.     

Auditory processing and perceptual abilities of “organic” and “functional” stutterers

The present investigation was undertaken to determine whether significant differences in auditory processing and perceptual abilities exist between (1) stutterers as a supposedly homogeneous group when compared with controls, (2) two differentiated subgroups of stutterers, and (3) either of the stuttering subgroups when separately compared with controls. Dichotic listening and masking level difference (MLD) tasks were administered to the two groups of school-age stutterers and an age-matched nonstuttering control group. Stuttering subjects were differentiated into “organic” and “functional” subgroups on the basis of neuropsychological test performances. Organic stutterers performed significantly poorer than did controls on one MLD experimental condition. Functional stutterers performed more like control subjects than like organic stutterers.     

Auditory feedback control in adults who stutter during metronome-paced speech I. Timing Perturbation

PurposeThis study determined whether adults who stutter (AWS) exhibit deficits in responding to an auditory feedback timing perturbation, and whether external timing cues, which increase fluency, attenuate any disruptions due to altered temporal auditory feedback.MethodsFifteen AWS and sixteen adults who do not stutter (ANS) read aloud a multisyllabic sentence either with normal pacing or with each syllable paced at the rate of a metronome. On random trials, an auditory feedback timing perturbation was applied, and timing responses were compared between groups and pacing conditions.ResultsBoth groups responded to the timing perturbation by delaying subsequent syllable boundaries, and there were no significant differences between groups in either pacing condition. Furthermore, no response differences were found between normally paced and metronome-paced conditions.ConclusionThese findings are interpreted as showing that 1) AWS respond normally to pure timing perturbations, and 2) metronome-paced speech has no effect on online speech timing control as assessed in the present experiment.     

The relationship between anxiety, fatigue and spontaneous recovery in stuttering

There is apparently no formalized hypothesis regarding the antecedents of spontaneous recovery of stuttering. Since adaptation and recovery appear to be functionally related, antecedents of adaptation have been considered to be antecedent to spontaneous recovery. Two disparate hypotheses of adaptation which have experimental support are the anxiety hypothesis and the fatigue hypothesis. The present study was initiated to investigate the relationship of anxiety and/or fatigue, if any, to spontaneous recovery. Twenty-one subjects (stutterers) participated in four conditions. Each condition consisted of eight oral readings of a passage. The experimental variables were introduced into the respective conditions after the fifth oral reading. They were: (I) no rest, same passage; (II) rest, same passage; (III) no rest, different passage; and, (IV) rest, different passage. Palmar sweat fingerprints of anxiety were taken concurrently with the first thirty seconds of trials one, three, five, six, seven and eight for all conditions. The results of the investigation led to the conclusions that: (1) there was no necessary relationship between a change in the frequency of stuttering and a change in the anxiety level ; (2) the Hullian concepts of reactive and conditioned inhibition appeared to provide a meaningful approach to the question of spontaneous recovery of stuttering behaviour.