Effect of reading with reversed speech on frequency of stuttering in adults

This study explored the effect of reading with reversed speech on the frequency of stuttering. Eight adults who stutter served as participants and read four 300-syllable passages while listening to three types of speech stimuli: normal speech (choral reading), reversed speech at normal speed, reversed speech at half speed, and a control condition of no auditory feedback. A repeated-measures analysis of variance showed a significant decrease in stuttering frequency in the choral reading condition but not in reversed speech at normal and half speed. However, the reversed speech at half-speed condition showed a large effect size (omega2 = 0.32). Data suggest that a forward moving speech feedback is not essential to decrease the frequency of stuttering in adults who stutter.     

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 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.     

Communicative stress and stuttering frequency during normal,whispered, and articulation-without-phonation speech modes

The effect of communicative stress on the frequency of stuttered syllables in 12 adult stutterers reading six different but equivalent passages using normal voicing, whispering, and articulation-without-phonation speech under a stress and a non-stress condition was studied. Although the frequency of stuttering was significantly greater in the normal voicing mode than in the whispering mode and greater in the whispering mode than in the articulation-without-phonation mode, no differences were found between the stress and the nonstress conditions with respect to stuttering.     

Differential levels of speech and manual dysfluency in adults who stutter during simultaneous drawing and speaking tasks

We examined the disruptive effects of stuttering on manual performance during simultaneous speaking and drawing tasks. Fifteen stuttering and fifteen non-stuttering participants drew continuous circles with a pen on a digitizer tablet under three conditions: silent (i.e., neither reading nor speaking), reading aloud, and choral reading (i.e., reading aloud in unison with another reader). We counted the frequency of stuttering events in the speaking tasks and measured pen stroke duration and pen stroke dysfluency (normalized jerk) in all three tasks. The control group was stutter-free and did not increase manual dysfluency in any condition. In the silent condition, the stuttering group performed pen movements without evidence of dysfluency, similar to the control group. However, in the reading aloud condition, the stuttering group stuttered on 12% of the syllables and showed increased manual dysfluency. In the choral reading condition stuttering was virtually eliminated (reduced by 97%), but manual dysfluency was reduced by only 47% relative to the reading aloud condition. Trials where more stuttered events were generally positively correlated with higher manual dysfluency. The results are consistent with a model in which episodes of stuttering and motor dysfluency are related to neural interconnectivity between manual and speech processes.     

Reaction time for voiced and whispered /a/ in stutterers and nonstutterers

Recent research reviewed in this article suggests that stutterers' inability to initiate phonation promptly could be a significant factor in the occurence of stuttering. Since stuttering is either completely absent or markedly reduced in frequency during whisper, the present study tested the hypothesis that stutterers do not significantly differ from nonstutterers in reaction time (RT) for the initiation of whispered/a/, whereas the two groups differ significantly in RT for the initiation of voiced /a/. Ten adult stutterers and an equal number of comparable nonstutterers produced prolonged versions of the vowel /a/ using voice and whisper in response to tone stimuli. The results showed that stutteres and nonstutterers did not differ in RT for either voiced or whispered /a/. The stutterers, however, exhibited significantly longer RT to produce voiced /a/ than whispered /a/.     

The role of temporal speech cues in facilitating the fluency of adults who stutter

PurposeAdults who stutter speak more fluently during choral speech contexts than they do during solo speech contexts. The underlying mechanisms for this effect remain unclear, however. In this study, we examined the extent to which the choral speech effect depended on presentation of intact temporal speech cues. We also examined whether speakers who stutter followed choral signals more closely than typical speakers did.Method8 adults who stuttered and 8 adults who did not stutter read 60 sentences aloud during a solo speaking condition and three choral speaking conditions (240 total sentences), two of which featured either temporally altered or indeterminate word duration patterns. Effects of these manipulations on speech fluency, rate, and temporal entrainment with the choral speech signal were assessed.ResultsAdults who stutter spoke more fluently in all choral speaking conditions than they did when speaking solo. They also spoke slower and exhibited closer temporal entrainment with the choral signal during the mid- to late-stages of sentence production than the adults who did not stutter. Both groups entrained more closely with unaltered choral signals than they did with altered choral signals.ConclusionsFindings suggest that adults who stutter make greater use of speech-related information in choral signals when talking than adults with typical fluency do. The presence of fluency facilitation during temporally altered choral speech and conversation babble, however, suggests that temporal/gestural cueing alone cannot account for fluency facilitation in speakers who stutter. Other potential fluency enhancing mechanisms are discussed.Educational Objectives: The reader will be able to (a) summarize competing views on stuttering as a speech timing disorder, (b) describe the extent to which adults who stutter depend on an accurate rendering of temporal information in order to benefit from choral speech, and (c) discuss possible explanations for fluency facilitation in the presence of inaccurate or indeterminate temporal cues.     

The effect of SpeechEasy on stuttering frequency, speech rate, and speech naturalness

The effects of SpeechEasy on stuttering frequency, stuttering severity self-ratings, speech rate, and speech naturalness for 31 adults who stutter were examined. Speech measures were compared for samples obtained with and without the device in place in a dispensing setting. Mean stuttering frequencies were reduced by 79% and 61% for the device compared to the control conditions on reading and monologue tasks, respectively. Mean severity self-ratings decreased by 3.5 points for oral reading and 2.7 for monologue on a 9-point scale. Despite dramatic reductions in stuttering frequency, mean global speech rates in the device condition increased by only 8% in the reading task and 15% for the monologue task, and were well below normal. Further, complete elimination of stuttering was not associated with normalized speech rates. Nevertheless, mean ratings of speech naturalness improved markedly in the device compared to the control condition and, at 3.3 and 3.2 for reading and monologue, respectively, were only slightly outside the normal range. These results show that SpeechEasy produced improved speech outcomes in an assessment setting. However, findings raise the issue of a possible contribution of slowed speech rate to the stuttering reduction effect, especially given participants' instructions to speak chorally with the delayed signal as part of the active listening instructions of the device protocol. Study of device effects in situations of daily living over the long term is necessary to fully explore its treatment potential, especially with respect to long-term stability. Educational objectives: The reader will be able to discuss and evaluate: (1) issues pertinent to evaluating treatment benefits of fluency aids and (2) the effects of SpeechEasy on stuttering frequency, speech rate, and speech naturalness during testing in a dispensing setting for a relatively large sample of adults who stutter.     

The effect of metronome pacing on selected aerodynamic patterns of stuttered speech: Some preliminary observations and interpretations

The purpose of this investigation was to provide some preliminary data regarding the effects of metronome pacing on physiological aspects of speech during stuttering. Five aerodynamic measures were chosen as dependent variables: (a) peak intraoral air pressure, (2) intraoral air pressure onset duration, (3) intraoral air pressure offset duration, (4) total intraoral air pressure duration, and (5) peak air flow rate. Five adult stutterers and five adult nonstutterers read a prose passage containing 12 English consonants, each in three syllable-initial stressed positions, during a control condition and experimental condition. In the experimental condition the subjects read the passage while synchronizing one word per beat at 60 beats per minute. The results demonstrated that both stutterers and normals evidenced lower peak pressures and greater pressure durations during metronome pacing. Air flow rates increased for normal subjects and decreased for stutterers in the experimental condition. Dysfluencies recorded during the control condition were observed to have much more rapid intraoral air pressure onsets when compared with fluent counterparts in the experimental reading. These results were interpreted with reference to Wingate's (1969) modified vocalization hypothesis and Van Riper's (1971) altered timing concept.     

Behavioral thresholds for tones during infancy

An adaptive up-down tracking procedure was used in combination with a visually reinforced head turn response to examine auditory sensitivity for 500, 2000, and 8000-Hz tone bursts in infants 6 to 18 months of age. Six- and 10-month-old infants were tested with headphone presentation of stimuli, while 10-, 14, and 18-month-olds were tested in sound field. Infant threshold estimates for both headphone and sound field were within 15 dB of adult comparisons for all frequencies and age groups. Six-month-olds were significantly less sensitive to the 8000-Hz tone than to either of the lower frequency stimuli, but older infants demonstrated approximately equal sensitivity for all three frequencies tested.     

Single band amplitude envelope cues as an aid to speechreading

Amplitude envelopes derived from speech have been shown to facilitate speech-reading to varying degrees, depending on how the envelope signals were extracted and presented and on the amount of training given to the subjects. In this study, three parameters related to envelope extraction and presentation were examined using both easy and difficult sentence materials: (1) the bandwidth and centre frequency of the filtered speech signal used to obtain the envelope; (2) the bandwidth of the envelope signal determined by the lowpass filter cutoff frequency used to “smooth” the envelope fluctuations; and (3) the carrier signal used to convey the envelope cues. Results for normal hearing subjects following a brief visual and auditory-visual familiarization/training period showed that (1) the envelope derived from wideband speech does not provide the greatest benefit to speechreading when compared to envelopes derived from selected octave bands of speech; (2) as the bandwidth centred around the carrier frequency increased from 12.5 to 1600 Hz, auditory-visual (AV) performance obtained with difficult sentence materials improved, especially for envelopes derived from high-frequency speech energy; (3) envelope bandwidths below 25 Hz resulted in AV scores that were sometimes equal to or worse than speechreading alone; (4) for each filtering condition tested, there was at least one bandwidth and carrier condition that produced AV scores that were significantly greater than speech-reading alone; (5) low-frequency carriers were better than high-frequency or wideband carriers for envelopes derived from an octave band of speech centred at 500 Hz; and (6) low-frequency carriers were worse than high-frequency or wideband carriers for envelopes derived from an octave band centred at 3150 Hz. These results suggest that amplitude envelope cues can provide a substantial benefit to speechreading for both easy and difficult sentence materials, but that frequency transposition of these signals to regions remote from their “natural” spectral locations may result in reduced performance.     

The effect of manual movements on stuttering in individuals with down syndrome

PurposeStuttering may disrupt the speech of individuals with Down syndrome (DS), but standard stuttering therapies may be less adapted to these clients’ needs. This study examined if their strength in gesture use can lead to the development of a new stuttering therapy.MethodEighteen individuals with DS who stutter participated in an experimental task. During this task, they produced sentences in three different conditions: once without the ability to use gestures, once while moving the mouth of a hand puppet synchronous with their speech, and once while making beat gestures along their speech. Stuttering frequency was measured and compared between conditions while controlling for the effect of articulation rate.ResultsThe experimental hand puppet and beat condition did not affect the stuttering frequency, but the covariate articulation rate did. An exploratory posthoc analysis showed that the articulation rate decreased during the experimental hand puppet and beat condition. Manual movements in the present task might only induce fluency through articulation rate reduction. However, analyses at individual level show significant interindividual variability.ConclusionIndividual analyses show that effect on stuttering frequency cannot be attributed entirely to articulation rate reduction and that beat gestures might still play a role. However, at this point, there is not enough direct evidence to implement beat gestures in current stuttering therapy.     

The slippery context effect in psychophysics: Intensive,extensive, and qualitative continua

When subjects gave magnitude estimates of 500- and 2500-Hz tones at various SPLs, they judged a 500-Hz tone of 60 dB to be as loud as a 2500-Hz tone of 57 dB in one context (low SPLs at 500 Hz, high SPLs at 2500 Hz), but as loud as a 2500-Hz tone at 40 dB in another context (high SPLs at 500 Hz, low at 2500 Hz) (Marks, 1988). Such shifts in matches derived from judgments of multi-dimensionally varying stimuli are termedslippery context effects. The present set of seven experiments showed that slippery effects were absent from judgments of pitch of tones at different loudnesses, duration of tones at different pitches, and length of lines at different colors, though a small effect emerged in judgments of duration of tones and lights. Slippery context effects were substantial when subjects gave magnitude estimates of loudness of 500- and 2500-Hz tones under conditions in which the pitch at each trial either was cued visually beforehand or could be known through the regular stimulus sequence, and with instructions to make absolute magnitude estimates. The results are consistent with the view that slippery context effects occur automatically and “preattentively.”     

The slippery context effect in psychophysics: intensive, extensive, and qualitative continua.

When subjects gave magnitude estimates of 500- and 2500-Hz tones at various SPLs, they judged a 500-Hz tone of 60 dB to be as loud as a 2500-Hz tone of 57 dB in one context (low SPLs at 500 Hz, high SPLs at 2500 Hz), but as loud as a 2500-Hz tone at 40 dB in another context (high SPLs at 500 Hz, low at 2500 Hz) (Marks, 1988). Such shifts in matches derived from judgments of multidimensionally varying stimuli are termed slippery context effects. The present set of seven experiments showed that slippery effects were absent from judgments of pitch of tones at different loudnesses, duration of tones at different pitches, and length of lines at different colors, though a small effect emerged in judgments of duration of tones and lights. Slippery context effects were substantial when subjects gave magnitude estimates of loudness of 500- and 2500-Hz tones under conditions in which the pitch at each trial either was cued visually beforehand or could be known through the regular stimulus sequence, and with instructions to make absolute magnitude estimates. The results are consistent with the view that slippery context effects occur automatically and "preattentively."     

Central and peripheral representation of whispered and voiced speech

Whispered speech is very different acoustically from normally voiced speech, yet listeners appear to have little trouble perceiving whispered speech. Two selective adaptation experiments explored the basis for the common perception of whispered and voiced speech, using two synthetic /ba/-/wa/ continua (one voiced, and one whispered). In the first experiment the endpoints of each series were used as adaptors, along with several nonspeech adaptors. Speech adaptors produced reliable labeling shifts of syllables matching in periodicity (i.e., whispered-whispered or voiced-voiced); somewhat smaller effects were found with mismatched periodicity. A periodic nonspeech tone with short rise time (the "pluck") produced adaptation effects like those for /ba/. These shifts occurred for whispered test syllables as well as voiced ones, indicating a common abstract level of representation for voiced and whispered stimuli. Experiment 2 replicated and extended Experiment 1, using same-ear and cross-ear adaptation conditions. There was perfect cross-ear transfer of the nonspeech adaptation effect, again implicating an abstract level of representation. The results support the existence of two levels of processing for complex acoustic signals. The commonality of whispered and voiced speech arises at the second, abstract level. Both this level, and the earlier, more directly acoustic level, are susceptible to adaptation effects.     

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.     

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.     

The effectiveness of SpeechEasy during situations of daily living

A multiple single-subject design was used to examine the effects of SpeechEasy on stuttering frequency in the laboratory and in longitudinal samples of speech produced in situations of daily living (SDL). Seven adults who stutter participated, all of whom had exhibited at least 30% reduction in stuttering frequency while using SpeechEasy during previous laboratory assessments. For each participant, speech samples recorded in the laboratory and SDL during device use were compared to samples obtained in those settings without the device. In SDL, stuttering frequencies were recorded weekly for 9-16 weeks during face-to-face and phone conversations. Participants also provided data regarding device tolerance and perceived benefits. Laboratory assessments were conducted at the beginning and the end of the longitudinal data collection in SDL. All seven participants exhibited reduced stuttering in self-formulated speech in the Device compared to No-device condition during the first laboratory assessment. In the second laboratory assessment, four participants exhibited less stuttering and three exhibited more stuttering with the device than without. In SDL, five of seven participants exhibited some instances of reduced stuttering when wearing the device and three of these exhibited relatively stable amounts of stuttering reduction during long-term use. Five participants reported positive changes in speaking-related attitudes and perceptions of stuttering. Further investigation into the short- and long-term effectiveness of SpeechEasy in SDL is warranted. Educational objectives: The reader will be able to summarize: (1) issues pertinent to evaluating treatment benefits of wearable fluency aids and evaluate (2) the effect of SpeechEasy on stuttering frequency and the perceived benefits of device use in situations of daily living, as assessed weekly over the course of 9-16 weeks of wear, for seven adults who stutter.     

Lingual vibrotactile and auditory cross-modal matching: frequency effects

5 subjects matched pairs of auditory and vibrotactile stimuli on intensity, making judgments of suprathreshold magnitudes. Slope values for the 100-Hz cross-modal lingual vibrotactile stimulus-standard frequency condition were steeper than those for 250- or 400-Hz conditions. Slope values became steeper at about 25- to 30-dB SL, so frequency seems an important parameter to control in such research.     

A positron emission tomography study of short- and long-term treatment effects on functional brain activation in adults who stutter

Previous studies have shown that fluency-inducing techniques, such as choral speech, result in changes in neural activation as measured by functional neuroimaging. In the present study, positron emission tomography was used to investigate the effects of intensive behavioural treatment, followed by a 1-year maintenance program, on the pattern of cortical and subcortical activation in stuttering adults during silent and oral reading of single words. The results indicate changes in activation lateralisation, as well as a general reduction in overactivation, especially in the motor cortex, following treatment. The results are discussed in light of previous functional imaging studies with stuttering adults.

Educational objectives: The reader will learn about and be able to describe the: (1) use of functional neuroimaging PET in the study of stuttering; (2) differences in neural activation between stuttering and non-stuttering adults; and (3) effects of behavioural fluency treatment on cortical and subcortical activations in stuttering speakers.