Does Articulatory Suppression Remove the Irrelevant Speech Effect?

Salamé and Baddeley (1982) reported that the effect of irrelevant speech on the serial recall of visually presented sequences was abolished when subjects performed articulatory suppression during presentation and recall of the target items. They argued that this is because suppression isolates visually presented material from the phonological store, which they consider to be the locus of the irrelevant speech effect. In the present experiment, an alternative interpretation of Salamé and Baddeley's findings was investigated. Salamé and Baddeley used nine-item sequences, and observed very low levels of recall when articulation was suppressed. It is therefore possible that Salamé and Baddeley's failure to observe any additional effect of irrelevant speech reflects either a floor effect or else a strategic choice by subjects to abandon the use of a phonological memory code because of task difficulty. In the experiment reported here, this issue was investigated by using both six- and nine-item sequences. Results revealed no effect of irrelevant speech under articulatory suppression even at the shorter sequence length. The results therefore replicate and extend the findings of Salamé and Baddeley (1982), and provide support for their view that visually presented material must be articulated before it becomes susceptible to interference from irrelevant speech.     

A speech-rate intelligibility threshold for speeded and time-compressed connected speech

An automated threshold method has been developed for determining the maximum rate of speech understood by individual listeners. Two experiments were undertaken to determine whether the threshold was related to the comprehension of speech or to speech intelligibility. The first experiment compared thresholds of two types of rapid speech reportedly different in intelligibility: simple speeded speech and speech compressed by the sampling method. The second experiment sought to determine the relationship of the threshold to traditional comprehension measures. The results are discussed in terms of the intelligibility and comprehensibility of speech.     

Accuracy of perceptual and acoustic methods for the detection of inspiratory loci in spontaneous speech

The present study investigates the accuracy of perceptually and acoustically determined inspiratory loci in spontaneous speech for the purpose of identifying breath groups. Sixteen participants were asked to talk about simple topics in daily life at a comfortable speaking rate and loudness while connected to a pneumotach and audio microphone. The locations of inspiratory loci were determined on the basis of the aerodynamic signal, which served as a reference for loci identified perceptually and acoustically. Signal detection theory was used to evaluate the accuracy of the methods. The results showed that the greatest accuracy in pause detection was achieved (1) perceptually, on the basis of agreement between at least two of three judges, and (2) acoustically, using a pause duration threshold of 300 ms. In general, the perceptually based method was more accurate than was the acoustically based method. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci for spontaneous speech should be weighed in selecting a method of breath group determination.     

The rate of internal speech in paced rehearsal

Hollnagel, E. The rate of internal speech in paced rehearsal. Scand. J. Psychol., 1973, 14, 241–243.-The purpose of the experiment was to measure the rate of internal speech in rehearsal. The method used was paced rehearsal, i. e. the subjects should synchronize their internal speech with an external signal. The known rate of the external signal, the pace rate, was used as an ndication of the rate of internal speech. For each subject the maximum pace rate was found, and the corresponding maximum rate of internal speech was calculated. The mean of the maximum rates of internal speech for 17 subjects was 126 ms/syllable. This is considerably faster than the results obtained from experimental studies up to now.     

The importance of semantic similarity to the irrelevant speech effect

Irrelevant speech disrupts immediate recall of a short sequence of items. Salamé and Baddeley (1982) found a very small and nonsignificant increase in the irrelevant speech effect when the speech comprised items semantically identical to the to-be-remembered items, leading subsequent researchers to conclude that semantic similarity plays no role in the irrelevant speech effect. Experiment 1 showed that strong free associates of the to-be-remembered items disrupted serial recall to a greater extent than words that were dissimilar to the to-be-remembered items. Experiment 2 showed that this same pattern of disruption in a free recall task. Theoretical implications of these findings are discussed.     

Spontaneous Imitation of Fundamental Frequency and Speech Rate by Nonstutterers and Stutterers

Speech can be described either in terms of acoustics, as a perceptual outcome, or as a motor event. Central to theories of speech perception and production is an attempt to describe how these aspects of speech are interrelated. The present experiment investigated how the nonstutterers' and stutterers' reproductions of acoustically presented interrogative sentences were influenced by experimental variations of intonation (sentence initial vs. sentence final) and speech rate (normal vs. time compressed). We studied the effects of these stimulus manipulations on the speech rate and fundamental frequency (F₀ ) of 10 adult German-speaking nonstutterers and seven stutterers. Experimental manipulations of intonation and speech rate significantly influenced the syllable duration and speech rate of both normal speakers and stutterers. The fundamental frequency of the subjects' responses were also significantly influenced by the intonation of the stimulus. But the stutterers' increase in F₀ for stressed syllables was generally less pronounced than that of nonstutterers. These results imply that (a) the subjects not only extract linguistic meaning from intonation but that they also store extragrammatical speech rate information, and (b) the speakers adopt these speech rate variations for their own productions. Generally, these results demonstrate that speech perception is not limited to extracting linguistically invariant information. The results show that speakers actively generate their own prosody and that this generative process is influenced by the prosodic structure of another speaker's antecedent speech. The implications of these results for theories of speech production are discussed.     

Acoustic determinants of perceptual center (P-center) location

Morton, Marcus, and Frankish (1976) defined “perceptual center,” or “P-center,” as a neutral term to describe that which is regular in a perceptually regular sequence of speech sounds. This paper describes a paradigm for the determination of P-center location and the effect of various acoustic parameters on empirically determined P-center locations. It is shown that P-center location is affected by both initial consonant duration and, secondarily, subsequent vowel and consonant duration. A simple two-parameter model involving the duration of the whole stimulus is developed and gives good performance in predicting P-center location. The application of this model to continuous speech is demonstrated. It is suggested that there is little value in attempting to determine any single acoustic or articulatory correlate of P-center location, or in attempting to define P-center location absolutely in time. Rather, these results indicate that P-centers are a property of the whole stimulus and reflect properties of both the production and perception of speech.     

语音告警信号语速研究

用普通会话句表和飞机告警句表两种测试材料 ,以言语可懂度测试法和主观评价法研究言语告警信号的适宜语速。实验中的语速定为 0 .1 1、0 .1 5、0 .2 0、0 .2 5、0 .3 5和 0 .45秒 /字六级。实验模拟飞机座舱环境 ,采用计算机生成的数字化言语信号 ,在 90 d B(A)的飞机噪声环境下 ,通过耳机传递给被试。研究得到以下结论 :言语告警信号的适宜语速为 0 .2 5秒 /字 (或 4字 /秒 ) ,它的下限为 >0 .2 0秒 /字 (或 <5字 /秒 ) ,它的上限为 0 .3 0秒 /字 (或 3 .3 3字 /秒 )。     

The validation of automatic methods for measuring conversational speech activity

Sophisticated electronic systems have been developed to measure speech activity patterns automatically, but their accuracy is unknown. The purpose of the present work is to evaluate the fidelity with which a class of computerized systems matches the measurements made by a human observer. With all parameters optimized, it was found that: (1) about 98% of samples (sampling rate = 200/sec) were classified the same way by the system and the criterion method; (2) distributions of utterance durations and speaker-switch intervals were accurately rendered by the automatic system; (3) average durations of talkspurts—bursts of speech activity within utterances—were closely approximated, but the system tended to overestimate the number of brief (?100 msec) talkspurts; (4) the system was subject to considerable qualitative error in the measurement of within-utterance pauses and of simultaneous talking.     

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.     

The relationship of estimated comprehensibility to the rate of connected speech

The relationship between subjective estimates of the comprehensibility of connected, freerunning speech and rate of speech was investigated for each of two types of time-compressed speech: pitch-varying speeded speech and pitch-normalized compressed speech. The midpoints of the resulting functions approximated the values obtained by a previously described speechrate tracking method. For equivalent degrees of comprehensibility, rates were higher for compressed speech than for speeded speech, indicating that estimates are sensitive to the intelligibility of speech. Subjective estimates of comprehensibility of time-compressed speech provide a means of assessing the itelligibility of connected speech.     

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.     

Effects of cognitive impairment on prosodic parameters of speech production planning in multiple sclerosis

Cognitive impairment (CI) affects 40–65% of patients with multiple sclerosis (MS). CI can have a negative impact on a patient's everyday activities, such as engaging in conversations. Speech production planning ability is crucial for successful verbal interactions and thus for preserving social and occupational skills. This study investigates the effect of cognitive-linguistic demand and CI on speech production planning in MS, as reflected in speech prosody. A secondary aim is to explore the clinical potential of prosodic features for the prediction of an individual's cognitive status in MS. A total of 45 subjects, that is 22 healthy controls (HC) and 23 patients in early stages of relapsing-remitting MS, underwent neuropsychological tests probing specific cognitive processes involved in speech production planning. All subjects also performed a read speech task, in which they had to read isolated sentences manipulated as for phonological length. Results show that the speech of MS patients with CI is mainly affected at the temporal level (articulation and speech rate, pause duration). Regression analyses further indicate that rate measures are correlated with working memory scores. In addition, linear discriminant analysis shows the ROC AUC of identifying MS patients with CI is 0.70 (95% confidence interval: 0.68–0.73). Our findings indicate that prosodic planning is deficient in patients with MS-CI and that the scope of planning depends on patients’ cognitive abilities. We discuss how speech-based approaches could be used as an ecological method for the assessment and monitoring of CI in MS.     

Tree structures, the work of listening, and schizophrenic discourse: A reply to Beveridge and Brown

A. W. Beveridge and K. Brown (Brain and Language, 24, 174-181) have criticized a study reported by R. Hoffman, L. Kirstein, S. Stopek, and D. Cicchetti (Brain and Language, 15, 207-233), which examined processing tasks imposed upon listeners by schizophrenic speech. The authors argue that our discourse analysis was not sufficiently objective since different discourse structures can at times be generated on the basis of a particular deviant speech segment. However, the analysis which we described does not purport to yield an "objective" structure of schizophrenic texts but rather attempts to reflect representations that individual listeners generate in processing speech; our model only requires that different interpretations of a particular segment generate different discourse structures. Deficiencies in hierarchical structure associated with schizophrenic speech increase processing requirements for listeners and may cause interpretive variability. Incoherence scores generated on the basis of our analysis were used to estimate the amount of extra "work of listening" that particular speech segments require. Because these incoherence scores were blindly and reliably determined, they can be used to make statistical inferences about the prevalence of structural deficiencies of schizophrenic speech compared to the speech of controls.     

Speech rate and the development of short-term memory span

Two experiments are reported which examine the effects of word duration on memory span in subjects of different ages. The same linear function relating recall to speech rate (assessed by the speed of repeating words) fits the results of subjects ranging in age from 4 years old to adulthood. It is concluded that developmental increases in short-term memory span can be explained in terms of increases in speech rate and that there is no evidence for an increase in short-term memory capacity. Analyses of the children's speech suggests that increases in speech rate with age reflect increases in the speed of articulation of individual words, rather than any change in the duration of pauses between successive words or changes in coarticulation between words.     

Accuracy of perceptually based and acoustically based inspiratory loci in reading

Investigations of speech often involve the identification of inspiratory loci in continuous recordings of speech. The present study investigates the accuracy of perceptually determined and acoustically determined inspiratory loci. While wearing a circumferentially vented mask connected to a pneumotach, 16 participants read two passages. The perceptually determined and acoustically determined inspiratory loci were compared with the actual loci of inspiration, which were determined aerodynamically. The results showed that (1) agreement across all three judges was the most accurate of the approaches considered here for detecting inspiratory loci based on listening; (2) the most accurate pause duration threshold for detecting inspiratory loci was 250 msec; and (3) the perceptually based breath-group determination was more accurate than the acoustically based determination of pause duration. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci are not negligible and, therefore, need to be considered when researchers design experiments on breath groups in speech.