Delayed auditory feedback and shadowing

On the basis of speech disturbance under binaural DAF, groups of subjects of high and low susceptibility were formed. Both groups were required to shadow messages presented under four conditions: single message presented binaurally; message presented to one ear with either white noise, an irrelevant message, or delayed feedback of the repetitition of the message, presented to the contralateral ear. For both groups the number of errors (omitted words) increased significantly in the irrelevant message and the delayed feedback conditions as compared with the binaural or white noise conditions. There was no difference between the susceptible and non-susceptible groups in the binaural and white noise conditions, but the susceptible group showed a much larger increase in the irrelevant message and delayed feedback conditions. Implications of these findings for theories of DAF are discussed.     

Delayed auditory feedback and movement

It is well known that timing of rhythm production is disrupted by delayed auditory feedback (DAF), and that disruption varies with delay length. We tested the hypothesis that disruption depends on the state of the movement trajectory at the onset of DAF. Participants tapped isochronous rhythms at a rate specified by a metronome while hearing DAF (for piano tones) of differing lengths. Motion capture was used to analyze movement trajectories. Mean Inter-Response Intervals (IRIs) varied as an approximately sinusoidal function of feedback condition, with DAF causing slowed production for shorter delays and speeded production for faster delays. Motion capture analyses revealed that finger velocity at the time of DAF predicted the effect of DAF on mean IRI whereas finger position predicted the variability of IRIs. A second experiment in which participants were instructed to vary the timing of peak finger height confirmed that the effect of DAF on timing variability is directly influenced by the finger trajectory.     

Adaptation to delayed auditory feedback

Delayed auditory feedback disrupts the production of speech, causing an increase in speech duration as well as many articulatory errors. To determine whether prolonged exposure to delayed auditory feedback IDAFI leads to adaptive compensations in speech production, 10 subjects were exposed in separate experimental sessions to both incremental and constantdelay exposure conditions. Significant adaptation occurred for syntactically structured stimuli in the form of increased speaking rates. After DAF was removed, aftereffects were apparent for all stimulus types in terms of increased speech rates. A carry-over effect from the first to the second experimental session was evident as long as 29 days after the first session. The use of strategies to overcome DAF and the differences between adaptation to DAF and adaptation to visual rearrangement are discussed.     

Twins' reactions to delayed auditory feedback

10 pairs of identical and 10 pairs of fraternal twins, matched by age, spoke under conditions of 0.0-, 100-, 200-, 300-, 400-, and 500-msec. delayed auditory feedback. Length of spoken passages was controlled. Product-moment and intraclass correlations were calculated for speaking times and disfluencies. Significant Pearson rs for times were noted at 0.0 and 300 msec. for both groups and at 100, 200, and 400 msec. for identical twins, while fraternal twins' times were significantly correlated at 500 msec. Difference scores were significantly correlated at 100, 200, 300, and 400 msec. for identical twins. Disfluencies were significantly correlated for identical twins at 400 msec. Data were combined with those of Timmons' (1969) study, increasing subjects to 21 pairs per group. Intraclass correlations supported the contention that responses of identical twin pairs to delayed auditory feedback were more highly correlated than those for fraternal twin pairs.     

Speech disruption under delayed auditory feedback in multilingual speakers

The present study investigated the language familiarity hypothesis formulated by Mackay [(1970). How does language familiarity influence stuttering under delayed auditory feedback? Perceptual and Motor Skills, 30, 655-669] that bilinguals speak faster and stutter less under delayed auditory feedback (DAF) when speaking their more familiar language than a less familiar language. Thirty normally fluent native speakers of Dutch (17 males and 13 females, aged between 18;1 and 26;4 years) who were also proficient in French and English read meaningful and nonsense text under DAF in their mother tongue and in the two later acquired languages. The existence of a language familiarity effect was confirmed. The participants required significantly more time and showed significantly more speech disruptions under DAF in the later acquired languages than in the mother tongue, and reading time and number of speech disruptions was significantly higher for the nonsense texts than for the meaningful text for each of the three languages. An additional question addressed was whether or not there were any gender differences in the susceptibility to DAF. Results did not reveal a clear gender difference. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) summarize the importance of language familiarity for the degree of speech disruption experienced by normally fluent multilingual speakers under delayed auditory feedback; and (2) describe gender differences in the susceptibility to delayed auditory feedback.     

Portable delayed auditory feedback device: A preliminary report

This writing is a preliminary report describing a prototype of a portable delayed auditory feedback device called the DYSTECH 1000. This writing and our observations are presented to stimulate review and feedback by our colleagues of the DYSTECH 1000 as a clinical and generalization tool.     

Speech disfluencies under normal and delayed auditory feedback conditions

20 male and 20 female adults, matched by age, read under conditions of normal and 113-, 152-, 200-, 253-, 307-, and 347-msec. delayed auditory feedback. Disfluency counts were correlated with delayed auditory feedback reactions which were changes in disfluencies under delay conditions. Pearson product-moment and Spearman's rbos were negative and significant for delay times of 113, 153, 200, and 253 msec. The Pearson product-moment correlation for 307 msec. was also negative and significant. Two groups of 11 adults were selected from the original sample on the basis of high and low initial disfluency counts. Their reactions to delayed auditory feedback were compared, using a 2-way analysis of variance with repeated measures (groups X delay times). Both main effects were significant but not their interaction.     

Speech production mechanisms in aphasia: A delayed auditory feedback study

Data collected from a delayed auditory feedback (DAF) study conducted by F. Boller, P. B. Vrtunski, Y. Kim, and J. L. Mack (1978, Cortex, 14, 212–226) were reanalyzed to determine if speech quality measures which were significantly affected during DAF could be operationalized and to ascertain which type of errors are responsible for the judgement. A second goal of this study was to determine if Conduction aphasics were relatively spared under conditions of DAF, as has been shown in previous studies. Twenty aphasic patients and ten controls were presented with several speech production tasks under two delay conditions and two simultaneous feedback conditions. Results indicated that only the category of vowel length produced a significant number of errors, suggesting that DAF affects articulatory implementation. Conduction aphasics showed the least effect of all the groups. These results support Wernicke's and Geschwind's model, in which Conduction aphasics have a disconnection between the sensory and motor images of words. In contrast, Broca's aphasics were the most affected group under DAF, suggesting that a major component of their disorder is phonetic in nature.     

Effects of delayed auditory feedback on timing of music performance

Three experiments examined effects of delayed auditory feedback (DAF) on music performance as a function of the temporal location of feedback onsets within produced inter-onset intervals (IOIs). In Experiment 1, pianists performed isochronous melodies at two production rates with different amounts of DAF. Timing variability decreased for DAF amounts that caused feedback onsets to occur halfway through IOIs (binary subdivisions) in a 500-ms, but not 600-ms, IOI rate condition. In Experiment 2, pianists performed melodies with DAF delays and chose a preferred rate. Performers chose slower rates for larger delays; preferred rates approximated twice the amount of DAF. Experiment 3 tested the possibility that subjects deliberately conceptualized subdivisions in Experiments 1 and 2. Performers were given (1) no instructions, (2) instructions to mentally subdivide produced events in two, or (3) instructions to mentally subdivide produced events in three, in different blocks. Instructions to subdivide reduced timing variability for larger feedback delays. These experiments indicate that DAF disruption is reduced by subdividing instructions and sometimes by coincidences of feedback onsets with subdivisions of produced intervals. Such facilitation may reflect the use of hierarchical cognitive plans in production.     

A low-cost solid state device for producing delayed auditory feedback

This paper presents a design for construction of a relatively low-cost solid state delayed auditory feedback device. The advantages of this unit are that it is reliable, flexible, easy to operate, and it does not require audio tape.