An interpretation of research on feedback interruption in speech

The controversial question of the scope of sensory control in the voluntary motor patterns involved in speech is examined by reviewing studies in which the auditory, tactile, and proprioceptive feedback channels have been distorted or interrupted. The author makes a case for open loop control of well-learned speech patterns under normal circumstances. The concept of internal feedback is introduced as a possible control system of skilled speech, whereas response feedback and external feedback are viewed as necessary for children developing speech or adults learning new speech patterns.     

Reading instruction and remediation with the aid of computer speech

In this paper, we describe the application of new computer and speech synthesis technologies for reading instruction. Stories are presented on the computer screen, and readers may designate words or parts of words that they cannot read for immediate speech feedback. The important contingency between speech sounds and their corresponding letter patterns is emphasized by displaying the letter patterns in reverse video as they are spoken. Speech feedback is provided by an advanced text-to-speech synthesizer (DECtalk). Intelligibility data are presented, showing that DECtalk can be understood almost as well as natural human speech by both normal adults and reading disabled children. Preliminary data from 26 disabled readers indicate that there are significant benefits of speech feedback for reading comprehension and word recognition, and that children enjoy reading with the system.     

Audience reaction as a determinant of the speaker's self-persuasion

This paper tests effects of audience feedback on speaker attitudes. One hundred and seven male subjects with initial beliefs on both sides of an issue (women's role) were assigned to speak for or against their own position; then an “audience” provided one of three types of feedback (speaker was sincere, speaker was insincere, no feedback) in a 2 × 2 × 3 design. Subjects who received sincere feedback showed greater change in the direction of their speech than did those who received insincere feedback. No feedback treatments resulted in intermediate change. This sincere > no feedback > insincere ordering of means held for both pro- and counterattitudinal speakers and for both pretest attitudes. A main effect for pretest attitude was also obtained. Two additional control groups allow for a separate analysis of the effects of (1) preparing and delivering the speech, and (2) audience reaction to the speech.     

From central pattern generator to sensory template in the evolution of birdsong

Central nervous networks, be they a part of the human brain or a group of neurons in a snail, may be designed to produce distinct patterns of movement. Central pattern generators can account for the development and production of normal vocal signals without auditory feedback in non-songbirds. Songbirds need auditory feedback to develop and maintain the normal song of their species. The prerequisite for the use of auditory feedback for the control of song is a set of acoustic criteria or a template to which voice must match. The template method perhaps evolved to free birds from fixed central pattern generators, resulting in the evolution of diverse and complex songs among oscine songbirds. The evolution of human speech may have followed a similar course.     

The effects of video and nonnegative social feedback on distorted appraisals of bodily sensations and social anxiety

The effects of video feedback and nonnegative feedback from other people were examined as possibly ameliorating distorted appraisals of bodily sensations, as well as subjective and physiological anxiety in socially anxious individuals. Nonnegative feedback from a confederate emphasized the absence of negative outcomes (e.g., did not seem to tremble) rather than the presence of positive outcomes (e.g., looked calm). Socially anxious students were randomly assigned to either the experimental group, which received video and social feedback (n=12), or the control group (n 13). Participants were asked to give a videotaped speech twice. After the first speech, the experimental group watched the videotape of their speech and received feedback from a confederate, whereas the control group watched the video of another person's speech. The intervention improved distorted appraisal of bodily sensations and anticipatory anxiety for the experimental group. However, there were no differential effects on anxiety between the groups during speeches.     

Further evaluation of self and peer judgements of speech with delayed auditory feedback

Fifteen undergraduate students recorded a standard reading passage under simultaneous auditory feedback (SAF) and delayed auditory feedback (DAF, 210 ms). These pairs were rated for articulation and fluency differences, reading rate differences, pitch differences, loudness differences, and overall differences in quality of speech by the fifteen speakers and by ten peer judges. Results suggest that naive speakers under DAF form a self-impression of the effects of DAF upon their speech that is not different from the qualitative ratings of independent peer judges. The hypothesis that there was no overall difference between self and peer ratings was not rejected. Implications for the use of DAF as a research or treatment modality, or as both, are discussed.     

Dependence of 'audio-phonatoric coupling' of speech rate and speech loudness]

The 'audio-phonatoric coupling' (APC) was investigated in two independent experiments. Slightly delayed auditory feedback (delay time 40 ms) of the subjects' own speech was used as experimental method. The first experiment was conducted to examine whether the strength of the APC depends on the speech rate. In this experiment 16 male Subjects (Ss) were required to utter the testword/tatatas/either with stress placing on the first or second syllable at two different speech rates (fast and slow). In 16% of the randomly chosen speech trials, the delayed auditory feedback (DAF; 40 ms delay) was introduced. It could be shown that the stressed phonation was significantly lengthened under the DAF condition. This lengthening was greater when Ss spoke slowly. The unstressed phonations were not influenced by the DAF condition. The second experiment was conducted to examine whether or not speech intensity effects APC. Nine male Ss were required to utter the testword/tatatas/either with stress placing on the first or second syllable using three different speech intensities (30 dB, 50 dB and 70 dB). In 16% of the randomly chosen speech trials DAF condition was introduced. It could be shown that speech intensity does not influence the DAF effect (lengthening of stressed phonation). These findings were taken as evidence that the auditory feedback of the subjects' own speech can be incorporated into speech control during ongoing speech. Obviously, this feedback information is efficient only during the production of stressed syllables, and varies as a function of speech rate. In addition, the significance of stressed syllables for the structuring of speech is discussed.     

Social feedback to infants' babbling facilitates rapid phonological learning

Infants' prelinguistic vocalizations are rarely considered relevant for communicative development. As a result, there are few studies of mechanisms underlying developmental changes in prelinguistic vocal production. Here we report the first evidence that caregivers' speech to babbling infants provides crucial, real-time guidance to the development of prelinguistic vocalizations. Mothers of 9.5-month-old infants were instructed to provide models of vocal production timed to be either contingent or noncontingent on their infants' babbling. Infants given contingent feedback rapidly restructured their babbling, incorporating phonological patterns from caregivers' speech, but infants given noncontingent feedback did not. The new vocalizations of the infants in the contingent condition shared phonological form but not phonetic content with their mothers' speech. Thus, prelinguistic infants learned new vocal forms by discovering phonological patterns in their mothers' contingent speech and then generalizing from these patterns.     

The Effect of Feedback Schedule Manipulation on Speech Priming Patterns and Reaction Time

Speech priming tasks are frequently used to delineate stages in the speech process such as lexical retrieval and motor programming. These tasks, often measured in reaction time (RT), require fast and accurate responses, reflecting maximized participant performance, to result in robust priming effects. Encouraging speed and accuracy in responding can take many forms, including verbal instructions and feedback, and often involves visually displayed RT feedback. However, it is uncertain how manipulation of the schedule of this RT feedback influences speech RT speed and, ultimately, the priming effect. This experiment examined the effect of visually presented RT feedback schedules on priming patterns in 20 older healthy adults. Results suggested that feedback schedule manipulation had a differential effect on reaction time, depending on the interstimulus interval between the prime and the target, but no effect on response priming patterns.     

Graduated exposure plus feedback in the treatment of speech anxiety

This study investigated the effectiveness of a graduated exposure procedure, combined with peer feedback, in the treatment of speech anxiety. Subjects were assigned to one of two conditions: (a) graduated exposure/shaping plus feedback or (b) no-treatment control. Results indicated that the graduated exposure/shaping plus feedback treatment group demonstrated significantly greater speech anxiety reduction than the no-treatment control group at post- and follow-up assessment.     

Feedback and fidelity: Effects of contingent consequences on accuracy of imitation

Accuracy of imitation by sixty kindergarten subjects was examined using a task in which a female adult modeled a series of pegboard patterns and delivered accuracy-contingent feedback. Four methods of feedback and a nofeedback control were compared. All four feedback groups were more accurate than the control group. The feedback conditions were: positive only, negative only, positive and negative, and negative with correction. The last condition resulted in greater accuracy than the others, which did not differ. All groups, including the control, improved significantly over trials. Accuracy of performance on interspersed, nonfeedback trials was maintained by feedback to the other patterns. Finally, imitation of repeating stimulus patterns did not differ from performance with nonrepeating patterns.     

Treatment of stammering by reinforcement of fluent speech

A series of small experimental studies was conducted with three stammerers. The studies show that stammering may be controlled by positive reinforcement of fluent speech in a machine reading task. This new procedure for the treatment of stammering is convenient and effective in producing fluent speech in the laboratory. Evidence suggests some generalization of a stable kind to outside settings.

Stammering interrupts speech and disturbs communication. It has been treated by a variety of methods, ranging from physical assault on the speech organs, through procedures designed to establish new speech patterns, training in deliberate speech control, and masking of auditory feedback, to psychotherapy and behaviour therapy.

Negative practice has brought about improvement in up to a third of cases (Dunlap, 1932; Fishman. 333 1937; Sheehan, 1953; Lehner, 1954; Jones, 1955; Case, 1960). The other common form of behaviour therapy has usually involved negative reinforcement or punishment. Flanagan, Goldiamond and Azrin (1958) used a loud blast of noise every time subjects stammered. Stammering rate was markedly depressed during the aversive conditioning, but when the aversive conditions were discontinued, stammering rate showed a pronounced increase. More recently, Goldiamond (1965) used fluency to terminate a noxious stimulus and reported a reduction in stammering.     

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.     

Comparison of the performances of a fluent and a nonfluent aphasic on a pantomimic referential task

The pantomimic performances of a typical Broca's (nonfluent) and Wernicke's (fluent) aphasic were compared with each other and with four normal control subjects on a simple task of nonverbal referential communication. Both aphasic subjects demonstrated only about 50% accuracy in their pantomimic communication. Also, measures were obtained of the motoric fluency of the pantomimes of all subjects and comparisons were made between the fluent and nonfluent aphasics. These measures demonstrated distinct differences in the fluency patterns of the pantomimes of the two aphasic subjects similar to the differences in speech fluency which distinguish and characterize these two types of aphasia; that is, the fluent aphasic pantomimed fluently and like the control subjects and the nonfluent aphasic pantomimed nonfluently. The quantitative and qualitative similarities in the fluency patterns of the speech and the pantomimic behaviors of the aphasic subjects are discussed in terms of their implications for a definition of aphasia.     

Detection of errors during speech production: a review of speech monitoring models

In this paper three theories of speech monitoring are evaluated. The perception-based approach proposes that the same mechanism employed in understanding other-produced language, the speech comprehension system, is also used to monitor one's own speech production. A conceptual, an inner, and an auditory loop convey information to a central, conscious monitor which scrutinizes the adequacy of the ongoing speech flow. In this model, only the end-products in the speech production sequences, the preverbal (propositional) message, the phonetic plan, and the auditory results, are verified. The production-based account assumes multiple local, autonomous monitoring devices, which can look inside formulation components. Moreover, these devices might be tuned to various signals from the actual speech motor execution, e.g. efferent, tactile, and proprioceptive feedback. Finally, node structure theory views error detection as a natural outflow of the activation patterns in the node system for speech production. Errors result in prolonged activation of uncommitted nodes, which in turn may incite error awareness. The approaches differ on the points of consciousness, volition and control, the number of monitoring channels, and their speed, flexibility, and capacity, and whether they can account for concurrent language comprehension disorders. From the empirical evidence presently available, it is argued for a central perception-based monitor, potentially augmented with a few automatic, production-based error detection devices.     

A real-time phoneme counting algorithm and application for speech rate monitoring

Adults who stutter can learn to control and improve their speech fluency by modifying their speaking rate. Existing speech therapy technologies can assist this practice by monitoring speaking rate and providing feedback to the patient, but cannot provide an accurate, quantitative measurement of speaking rate. Moreover, most technologies are too complex and costly to be used for home practice. We developed an algorithm and a smartphone application that monitor a patient’s speaking rate in real time and provide user-friendly feedback to both patient and therapist. Our speaking rate computation is performed by a phoneme counting algorithm which implements spectral transition measure extraction to estimate phoneme boundaries. The algorithm is implemented in real time in a mobile application that presents its results in a user-friendly interface. The application incorporates two modes: one provides the patient with visual feedback of his/her speech rate for self-practice and another provides the speech therapist with recordings, speech rate analysis and tools to manage the patient’s practice. The algorithm’s phoneme counting accuracy was validated on ten healthy subjects who read a paragraph at slow, normal and fast paces, and was compared to manual counting of speech experts. Test-retest and intra-counter reliability were assessed. Preliminary results indicate differences of −4% to 11% between automatic and human phoneme counting. Differences were largest for slow speech. The application can thus provide reliable, user-friendly, real-time feedback for speaking rate control practice.     

Strength of German accent under altered auditory feedback.

Borden's (1979, 1980) hypothesis that speakers with vulnerable speech systems rely more heavily on feedback monitoring than do speakers with less vulnerable systems was investigated. The second language (L2) of a speaker is vulnerable, in comparison with the native language, so alteration to feedback should have a detrimental effect on it, according to this hypothesis. Here, we specifically examined whether altered auditory feedback has an effect on accent strength when speakers speak L2. There were three stages in the experiment. First, 6 German speakers who were fluent in English (their L2) were recorded under six conditions--normal listening, amplified voice level, voice shifted in frequency, delayed auditory feedback, and slowed and accelerated speech rate conditions. Second, judges were trained to rate accent strength. Training was assessed by whether it was successful in separating German speakers speaking English from native English speakers, also speaking English. In the final stage, the judges ranked recordings of each speaker from the first stage as to increasing strength of German accent. The results show that accents were more pronounced under frequency-shifted and delayed auditory feedback conditions than under normal or amplified feedback conditions. Control tests were done to ensure that listeners were judging accent, rather than fluency changes caused by altered auditory feedback. The findings are discussed in terms of Borden's hypothesis and other accounts about why altered auditory feedback disrupts speech control.     

The speech and vocalization patterns of boys with ADHD compared with boys with dyslexia and boys without learning disabilities

This research study dealt with an inquiry into the speech and vocalization patterns of boys with Attention Deficit Hyperactivity Disorder (ADHD) who were not under the influence of stimulating medication, compared with the speech and vocalization patterns of boys with reading disabilities and a control group of learners without learning disabilities. The voices of 105 participants were recorded during interviews and analyzed in the laboratory using equipment that examined the temporal speech patterns and physical features of vocalization. The speech patterns were examined with a frequency examination, speech unit length duration, and correlation between the vocalization and pauses in the speech unit. The physical features of vocalization were examined with volume and frequency scales. The research results indicated that the speech and vocalization patterns of boys with ADHD were significantly different from those of boys with reading disabilities and from the boys in the control group. The results support the assumption that speech and vocalization indicators can be used as objective indicators for the diagnosis of hyperactivity syndrome with attention and concentration difficulties.     

Self-attribution of attitude as a function of belief feedback

Previous research has found that subjects listening to a communication can be persuaded more when they receive false physiological feedback concerning their emotional state than when such feedback is not presented. Such results, in conjunction with Bem's (1972) postulate that subjects infer their attitude from the external circumstances of their behavior, suggested that false feedback of belief or disbelief would affect persuasion. Subjects listened to a speech while observing their (false) reactions on a "belief meter." Half of the subjects received strong positive belief feedback, and the other half received strong disbelief feedback. Demand characteristics were varied by telling half of the subjects in each group that the meter was highly reliable and valid and the other half that is was of questionable validity. Results showed that the meter feedback affected self-attributions of attitude. Subjects receiving disbelief feedback rated their attitude the same as a control group who merely completed the attitude scale. Subjects receiving belief feedback were persuaded more than a control group receiving only the communication. The implications of the data for the construct of attitude were discussed.