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.     

Significance of pauses for speech perception

Pauses can be used to facilitate certain operations involved in the production and in the perception of speech. In the case of speech perception, pauses have been found to improve the accuracy of detection and the recall of lists of digits and letters. The aim of the present experiments was to examine the effects of pause time on the perception of sentences. In experiment I, a semantic categorization task was used and in experiment II a sentence recall task. The results indicated that in sentences containing pauses between clauses, words were categorized more rapidly (experiment I) and propositions were recalled more accurately (experiment II) than in sentences containing pauses, within the clause. The results are interpreted in the context of existing models of speech processing, and the significane of pause time for cognitive activity is discussed.     

Response organization in selective adaptation to speech sounds

Previous experiments in speech perception using the selective adaptation procedure have found a shift in the locus of the category boundary for a series of speech stimuli following repeated exposure to an adapting syllable. The locus of the boundary moves toward the category of the adapting syllable. Most investigators have interpreted these findings in terms of feature detector models in which specific detectors are reduced in sensitivity through repeated adaptation. The present experiment was conducted to determine whether the adaptation results might be due to changes in response organization as a consequence of the labeling instructions presented to subjects in selective adaptation experiments. A perceptually ambiguous speech stimulus was selected from the middle of a [bi]-[di] test series and used as an adaptor under two different sets of instructions. One group of subjects was told that the adapting stimulus was the syllable [bi], while another group was told that the stimulus was the syllable [di]. The acoustically ambiguous adaptor failed to produce a shift in the locus of the category boundary in the direction predicted on the basis of the labeling instructions presented to subjects. These results indicate that the acoustic attributes and perceived quality of the adapting stimulus determine the direction and magnitude of the adaptation effects rather than the labels provided by the experimenter.     

Effects of increased processing load on parallel processing of visual displays

Display elements were sequentially painted upon a display scope in regular and irregular spatial-temporal orders. The primary result of Mayzner, Tresselt, and their associates is confirmed: within specified temporal-spatial limits, display elements may be perceptually blanked. Characteristics of perceptually blanked elements can, however, be revealed by forced-choice testing. The accuracy of tilt discrimination for perceptually blanked elements is equal to, or better than, that for nonblanked elements. Perceptually blanked elements can also be distinguished from absent and from partially absent elements, presumably on the basis of a crude brightness discrimination. Sequential blanking effects as revealed in the accuracy of slant detection, are not critically dependent upon the magnitude of uniform spacing between the display elements.     

Acoustic correlates of subjective pauses

This study investigates the perception of subjective pauses, i.e., pauses that do not correspond to silent pauses. Experiment I used stimuli which were excerpts from spontaneous speech which were presented in two versions: spectrally normal and spectrally inverted. Experiment II used stimuli which were generated by first cross-splicing the two halves of two sentences; they were further manipulated for fundamental frequency, intensity, or duration of the vowel just preceding the splice point. The task in both experiments was to press a button when a speech interruption was heard. The purpose of the experiments was to identify the grammatical and acoustic correlates of the subjective pauses thus reported. The results of Experiment I show, for the inverted speech condition, but not for the normal speech condition, an increase in pause reports as the duration of the prepausal vowel increased. The results of Experiment II show an increase in pause reports with increasing vowel duration. The implications of increased prepausal duration functioning as a pause signal are discussed.     

The Impact and Status of Carol Fowler's Supramodal Theory of Multisensory Speech Perception

ABSTRACT

One important contribution of Carol Fowler's direct approach to speech perception is its account of multisensory perception. This supramodal account proposes a speech function that detects supramodal information available across audition, vision, and touch. This detection allows for the recovery of articulatory primitives that provide the basis of a common currency shared between modalities as well as between perception and production. Common currency allows for perceptual experience to be shared between modalities and supports perceptually guided speaking as well as production-guided perception. In this report, we discuss the contribution and status of the supramodal approach relative to recent research in multisensory speech perception. We argue that the approach has helped motivate a multisensory revolution in perceptual psychology. We then review the new behavioral and neurophysiological research on (a) supramodal information, (b) cross-sensory sharing of experience, and (c) perceptually guided speaking as well as production guided speech perception. We conclude that Fowler's supramodal theory has fared quite well in light of this research.     

Reaction times to comparisons within and across phonetic categories

Same-different reaction times (RTs) were obtained to pairs of synthetic speech sounds ranging perceptually from /ba/ through /pa/. Listeners responded “same” if both stimuli in a pair were the same phonetic segments (i.e., /ba/-/ba/ or /pa/-/pa/) or “different” if both stimuli were different phonetic segments (i.e., /ba/-/pa/ or /pa/-/ba/). RT for “same” responses was faster to pairs of acoustically identical stimuli (A-A) than to pairs of acoustically different stimuli (A-a) belonging to the same phonetic category. RT for “different” responses was faster for large acoustic differences across a phonetic boundary than for smaller acoustic differences across a phonetic boundary. The results suggest that acoustic information for stop consonants is available to listeners, although the retrieval of this information in discrimination will depend on the level of processing accessed by the particular information processing task.     

The perception of /r/ and /l/ in syllable-initial and syllable-final position

American English liquids /r/ and /l/ have been considered intermediate between stop consonants and vowels acoustically, articulatorily, phonologically, and perceptually. Cutting (1947a) found position-dependent ear advantages for liquids in a dichotic listening task: syllable-initial liquids produced significant right ear advantages, while syllable-final liquids produced no reliable ear advantages. The present study employed identification and discrimination tasks to determine whether /r/and /l/ are perceived differently depending on syllable position when perception is tested by a different method. Fifteen subjects listened to two synthetically produced speech series—/li/ to /ri/ and /il/ to /ir/—in which stepwise variations of the third formant cued the difference in consonant identity. The results indicated that: (1) perception did not differ between syllable positions (in contrast to the dichotic listening results), (2) liquids in both syllable positions were perceived categorically, and (3) discrimination of a nonspeech control series did not account for the perception of the speech sounds.     

Detecting silent pauses in speech: a new tool for measuring on-line lexical and semantic processing

In this study, we introduce pause detection (PD) as a new tool for studying the on-line integration of lexical and semantic information during speech comprehension. When listeners were asked to detect 200-ms pauses inserted into the last words of spoken sentences, their detection latencies were influenced by the lexical-semantic information provided by the sentences. Listeners took longer to detect a pause when it was inserted within a word that had multiple potential endings, rather than a unique ending, in the context of the sentence. An event-related potential (ERP) variant of the PD procedure revealed brain correlates of pauses as early as 101 to 125 ms following pause onset and patterns of lexical-semantic integration that mirrored those obtained with PD within 160 ms of pause onset. Thus, both the behavioral and the electrophysiological responses to pauses suggest that lexical and semantic processes are highly interactive and that their integration occurs rapidly during speech comprehension.     

Perception and immediate recall of normal and “compressed” auditory sequences

For a fixed presentation rate, the ratio of speech-to-pause time was varied in three experiments. Ss recalled seven-digit sequences or monitored for item or order information in addition to recall. Removing 33% of the speech and substituting pause time improved recall accuracy and monitoring reaction times. The data suggest that loss of order information in recall may result from cumulative perceptual delays when adequate pause time is unavailable.     

Attention orienting effects of hesitations in speech: evidence from ERPs

Filled-pause disfluencies such as um and er affect listeners' comprehension, possibly mediated by attentional mechanisms (J. E. Fox Tree, 2001). However, there is little direct evidence that hesitations affect attention. The current study used an acoustic manipulation of continuous speech to induce event-related potential components associated with attention (mismatch negativity [MMN] and P300) during the comprehension of fluent and disfluent utterances. In fluent cases, infrequently occurring acoustically manipulated target words gave rise to typical MMN and P300 components when compared to nonmanipulated controls. In disfluent cases, where targets were preceded by natural sounding hesitations culminating in the filled pause er, an MMN (reflecting a detection of deviance) was still apparent for manipulated words, but there was little evidence of a subsequent P300. This suggests that attention was not reoriented to deviant words in disfluent cases. A subsequent recognition test showed that nonmanipulated words were more likely to be remembered if they had been preceded by a hesitation. Taken together, these results strongly implicate attention in an account of disfluency processing: Hesitations orient listeners' attention, with consequences for the immediate processing and later representation of an utterance.     

Perceptual comparisons of adolescent stutterers' and nonstutterers' fluent speech

Numerous investigators have reported that listeners are able to perceptually differentiate adult stutterers' and nonstutterers' fluent speech productions. However, findings from similar studies with children ranging in age from 3 to 9 yr have indicated that perceptual discrimination of child stutterers is difficult. A logical extension of this line of investigation would be to determine when during maturation from childhood to adulthood stutterers' fluent speech becomes perceptibly different than nonstutterers'. Therefore, in this study similar fluent speech samples from seven 12–16-yr-old adolescent male stutterers and seven matched nonstutterers were analyzed perceptually in a paired stimulus paradigm by 15 sophisticated listeners. Individual subject analyses using signal detection theory revealed that five of the seven stutterers were discriminated. When averaged for subject group comparison, these findings indicated that listeners successfully discriminated between the fluent speech of the two groups. Therefore, the perceptual difference in fluent speech production reported previously for adults appears to be present by adolescence.     

Fluency Profiling System: An automated system for analyzing the temporal properties of speech

The temporal characteristics of speech can be captured by examining the distributions of the durations of measurable speech components, namely speech segment durations and pause durations. However, several barriers prevent the easy analysis of pause durations: The first problem is that natural speech is noisy, and although recording contrived speech minimizes this problem, it also discards diagnostic information about cognitive processes inherent in the longer pauses associated with natural speech. The second issue concerns setting the distribution threshold, and consists of the problem of appropriately classifying pause segments as either short pauses reflecting articulation or long pauses reflecting cognitive processing, while minimizing the overall classification error rate. This article describes a fully automated system for determining the locations of speech–pause transitions and estimating the temporal parameters of both speech and pause distributions in natural speech. We use the properties of Gaussian mixture models at several stages of the analysis, in order to identify theoretical components of the data distributions, to classify speech components, to compute durations, and to calculate the relevant statistics.     

Hierarchical coding in speech timing

The analysis of syllable and pause durations in speech production can provide information about the properties of a speaker's grammatical code. The present study was conducted to reveal aspects of this code by analyzing syllable and pause durations in structurally ambiguous sentences. In Experiments 1–6, acoustical measurements were made for a key syllabic segment and a following pause for 10 or more speakers. Each of six structural ambiguities, previously unrelated, involved a grammatical relation between the constituent following the pause and one of two possible constituents preceding the pause. The results showed lengthening of the syllabic segments and pauses for the reading in which the constituent following the pause was hierarchically dominated by the higher of the two possible preceding constituents in a syntactic representation. The effects were also observed, to a lesser extent, when the structurally ambiguous sentences were embedded in disambiguating paragraph contexts (Experiment 7). The results show that a single hierarchical principle can provide a unified account of speech timing effects for a number of otherwise unrelated ambiguities. This principle is superior to a linear alternative and provides specific inferences about hierarchical relations among syntactic constituents in speech coding.     

Pause loci in stuttered and normal speech

The mainstream of research comparing types of disfluency in stuttered and normal speech has typically omitted consideration of pause. In contrast, psycholinguisticresearch addressed to disfluency in normal speech alone has revealed the salience of pause in the study of fluency/disfluency. The research reported here, which focused on the antecedents and sequelae of filled pauses, revealed substantial differences in pattern of pause occurrence between stuttered and normal speech samples obtained from 20 matched subjects. The results are discussed in reference to relevant findings from the research on pause in normal speech.     

Resolving power of the perceptual- and sensorimotor systems in 6- to 10-year-old children

Children aged 6 to 10 were tested on their ability to move accurately and to perceptually evaluate their motor response. Subjects performed a directional and an amplitude visuo-manual aiming task without vision of their moving limb. They were asked to correct their error, after completion of their movements, only if they felt they were not accurate. Terminal aiming errors and correction responses (adjustments) were analyzed, and threshold detection was determined relative to terminal aiming error. Action accuracy and evaluation of action accuracy are two abilities that do not develop synchronously. Moreover, the relationship between these abilities depends on whether accuracy and direction or amplitude are required. Amplitude undergoes more corrections than direction, suggesting that the spatial system of reference involved depends more upon the coding of the final position than on direction. Two spatial comparators, operating on the basis of two types of evaluation, seem to have a variably distinct contribution to movement and perception accuracy, according to age.     

Resolving Power of the Perceptual-and Sensorimotor Systems in 6- to 10-Year-Old Children

Children aged 6 to 10 were tested on their ability to move accurately and to perceptually evaluate their motor response. Subjects performed a directional and an amplitude visuo-manual aiming task without vision of their moving limb. They were asked to correct their error, after completion of their movements, only if they felt they were not accurate. Terminal aiming errors and correction responses (adjustments) were analyzed, and threshold detection was determined relative to terminal aiming error. Action accuracy and evaluation of action accuracy are two abilities that do not develop synchronously. Moreover, the relationship between these abilities depends on whether accuracy and direction or amplitude are required. Amplitude undergoes more corrections than direction, suggesting that the spatial system of reference involved depends more upon the coding of the final position than on direction. Two spatial comparators, operating on the basis of two types of evaluation, seem to have a variably distinct contribution to movement and perception accuracy, according to age.     

Fluency breaks in older speakers: Implications for a model of stuttering throughout the life cycle

In order to test a model describing the occurence of fluency breaks throughout the life cycle, spontaneous speech samples of 40 nonstutterers and 4 stutterers above the age of 50 were perceptually analyzed. Fluency breaks were classified into categories of formulative or motoric breaks. The results supported research, noting an increase in formulative fluency breaks (especially fillers and interjections) for older speakers. There was, however, a significant decrease in the occurence of formulative fluency breaks during the final years of late adulthood. No change was found in the occurence of motoric fluency breaks in the nonstuttering speakers. Stuttering speakers had significantly less formulative breaks and significantly more motoric breaks than nonstuttering speakers.     

Switching pauses in adult-adult and child-child turn takings: An initial study

Based on the Japanese conversation obtained from five adult-adult and five child-child dyads, the present study investigated whether the duration of switching pause (silence between two different speakers) differed depending on the existence of linguistic cue (e.g., anaphoric reference) and/or the phonetic cue (rising intonation). Switching pause durations were measured acoustically whereas the phonetic cue was examined by a listening test. The results showed that switching pause durations are likely to be short when they are accompanied by the linguistic cue whereas they are likely to be long when accompanied by no cue. This tendency was observed both in adult and child dyads. The results also showed that the ratios of using the linguistic and/or the phonetic cue are almost the same for adults and children.