Factors affecting judgments of fluency: I. interjections

Six speech samples containing varying amounts of schwa interjections were tape-recorded and presented to 36 male and 36 female listeners. For each sample, listeners were asked to make judgments of fluent, disfluent, and stuttered speech, and to answer the question “Would you recommend speech therapy?” Results indicated that speech samples containing 5% or more interjections evoked a judgment of disfluent speech by a majority of listeners. The sample containing 20% interjections, however, was found to evoke judgments of disfluent and stuttered speech about equally. Varying numbers of listeners recommended clinical services for disfluent speech. In general, the results indicated that (1) the presence of interjections in connected speech is not normal regardless of frequency, (2) fluent speech may not contain interjections in excess of 5%, and (3) with 20% interjections in speech, the distinction between disfluency and stuttering may be blurred.     

Sudden onset of excessive repetitions in the speech of a patient with multiple sclerosis: A case report

This report provides a detailed analysis of excessive part- and whole-word repetitions in the speech of a 36-year-old male patient hospitalized for treatment of multiple sclerosis (MS) who also exhibited concurrent language and prosodic disturbances. Shortly following his hospitalization, a magnetic resonance imaging examination revealed plaques in the white matter of the medulla, cerebellum, basal ganglion, and periventricular white matter. His speech strongly resembled apractic speech patterns, chiefly syllable segregation. The source of data collected for this study was seven tape-recorded speech samples containing 2536 words spoken in 32.75 min, diagnostic reports, and clinical notes of 27 biweekly speech therapy sessions across a 5-month period. This report focused on an analysis of variables associated with the patient's part- and whole-word repetitions, and it was concluded that they were used as a compensatory device to procure additional time to articulate complex syllables. A brief critique of the therapeutic procedures used for treating his speech problem is also presented.

Educational objectives: The reader will learn about and be able to describe (1) the effects of MS on speech and language; (2) the kinds of data that were gathered to account for this patient's sudden onset of speech and language disorders; and (3) the findings that led them to conclude that his excessive repetitions were compensatory behaviors.     

Identifying the speech codes

Models of speech processing typically assume that speech is represented by a succession of codes. In this paper we argue for the psychological validity of a prelexical (phonetic) code and for a postlexical (phonological) code. Whereas phonetic codes are computed directly from an analysis of input acoustic information, phonological codes are derived from information made available subsequent to the perception of higher order (word) units. The results of four experiments described here indicate that listeners can gain access to, or identify, entities at both of these levels. In these studies listeners were presented with sentences and were asked to respond when a particular word-initial target phoneme was detected (phoneme monitoring). In the first three experiments speed of lexical access was manipulated by varying the lexical status (word/nonword) or frequency (high/low) of a word in the critical sentences. Reaction times (RTs) to target phonemes were unaffected by these variables when the target phoneme was on the manipulated word. On the other hand, RTs were substantially affected when the target-bearing word was immediately after the manipulated word. These studies demonstrate that listeners can respond to the prelexical phonetic code. Experiment IV manipulated the transitional probability (high/low) of the target-bearing word and the comprehension test administered to subjects. The results suggest that listeners are more likely to respond to the postlexical phonological code when contextual constraints are present. The comprehension tests did not appear to affect the code to which listeners responded. A “Dual Code” hypothesis is presented to account for the reported findings. According to this hypothesis, listeners can respond to either the phonetic or the phonological code, and various factors (e.g., contextual constraints, memory load, clarity of the input speech signal) influence in predictable ways the code that will be responded to. The Dual Code hypothesis is also used to account for and integrate data gathered with other experimental tasks and to make predictions about the outcome of further studies.     

Lexical tone in Cantonese spoken-word processing

In three experiments, the processing of lexical tone in Cantonese was examined. Cantonese listeners more often accepted a nonword as a word when the only difference between the nonword and the word was in tone, especially when theF0 onset difference between correct and erroneous tone was small.Same-different judgments by these listeners were also slower and less accurate when the only difference between two syllables was in tone, and this was true whether theF0 onset difference between the two tones was large or small. Listeners with no knowledge of Cantonese produced essentially the samesame-different judgment pattern as that produced by the native listeners, suggesting that the results display the effects of simple perceptual processing rather than of linguistic knowledge. It is argued that the processing of lexical tone distinctions may be slowed, relative to the processing of segmental distinctions, and that, in speeded-response tasks, tone is thus more likely to be misprocessed than is segmental structure.     

Unsophisticated judges' perceptual evaluations of the speech of “successfully treated” stutterers

The purpose of this investigation was to determine if the speech of “successfully therapeutized” stutterers and a group of partially treated stutterers was perceptually different from the speech of normal speakers when judged by unsophisticated listeners. Tape-recorded speech samples of treated stutterers were obtained from leading proponents of (1) Van Riperian, (2) metronome-conditioned speech retraining, (3) delayed auditory feedback, (4) operant conditioning, (5) precision fluency shaping, and (6) “holistic” therapy programs. Fluent speech samples from these groups of stutterers were paired with matched fluent samples of normal talkers and presented to a group of 20 unsophisticated judges. The judges were instructed to select from each paired speech sample presented to them the one produced by the stuttering subject. The results of the analyses showed that five of seven experimental groups were identified at levels significantly above chance. It can be concluded that the fluent speech of the partially and successfully treated stutterers was perceptibly different from the utterances of the normal speakers and that the perceptual disparity can be detected, even by unsophisticated listeners.     

Not all disfluencies are are equal: The effects of disfluent repetitions on language comprehension

Disfluencies can affect language comprehension, but to date, most studies have focused on disfluent pauses such as er. We investigated whether disfluent repetitions in speech have discernible effects on listeners during language comprehension, and whether repetitions affect the linguistic processing of subsequent words in speech in ways which have been previously observed with ers. We used event-related potentials (ERPs) to measure participants’ neural responses to disfluent repetitions of words relative to acoustically identical words in fluent contexts, as well as to unpredictable and predictable words that occurred immediately post-disfluency and in fluent utterances. We additionally measured participants’ recognition memories for the predictable and unpredictable words. Repetitions elicited an early onsetting relative positivity (100–400 ms post-stimulus), clearly demonstrating listeners’ sensitivity to the presence of disfluent repetitions. Unpredictable words elicited an N400 effect. Importantly, there was no evidence that this effect, thought to reflect the difficulty of semantically integrating unpredictable compared to predictable words, differed quantitatively between fluent and disfluent utterances. Furthermore there was no evidence that the memorability of words was affected by the presence of a preceding repetition. These findings contrast with previous research which demonstrated an N400 attenuation of, and an increase in memorability for, words that were preceded by an er. However, in a later (600–900 ms) time window, unpredictable words following a repetition elicited a relative positivity. Reanalysis of previous data confirmed the presence of a similar effect following an er. The effect may reflect difficulties in resuming linguistic processing following any disruption to speech.     

Word fragmentations and repetitions in the spontaneous speech of 2–6-yr-old children

Samples of spontaneous speech of 110 nursery school children, aged 2 yr, 1 mo to 6 yr, were written down. Two of the children were regarded as stutterers by the parents and the nursery school personnel. Instances of word and phrase repetitions and word fragmentations were marked. Fragmentation of a word before the whole word is pronounced was used as criterion of stuttering. The nonstutterers had an average frequency of word repetitions of 6.3%, while word fragmentations were virtually nonoccurrent. The frequency of word repetitions decreased with increasing age. Relating word repetitions to grammatical complexity of speech, it was found that the decrease was particularly large at a certain point of the grammatical development. The two stutterers had, in addition to normal frequencies of word repetitions, marked occurences of word fragmentations (2.8 and 4.1%).     

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.     

How school-aged students define stuttering and stammering

Fifty students from each of the grades 2, 4, 6, 8, 10, and 12 were asked to complete a questionnaire containing the following three questions: 1) What is stuttering? 2) What is stammering? 3) How did you know that? Analysis of their responses indicated students were more familiar with stuttering as opposed to the term stammering. From grade 6 onward, we can expect at least three-fourths of the students to define stuttering as a disruption of speech consisting chiefly of sound or syllable repetitions. Only about one-fourth of students in grade 6 and above defined stammering as a speech disruption. This disruption was characterized chiefly by repetitions, injections, and pauses. Most of the students were unable to specify how they learned the definitions. The few who did identified family and friends as their chief source of knowledge.     

Infants’ sensitivity to allophonic cues for word segmentation

A series of four experiments was conducted to determine whether English-learning infants can use allophonic cues to word boundaries to segment words from fluent speech. Infants were familiarized with a pair of two-syllable items, such asnitrates andnight rates and then were tested on their ability to detect these same words in fluent speech passages. The presence of allophonic cues to word bound-aries did not help 9-month-olds to distinguish one of the familiarized words from an acoustically similar foil. Infants familiarized withnitrates were just as likely to listen to a passage aboutnight rates as they were to listen to one aboutnitrates. Nevertheless, when the passages contained distributional cues that favored the extraction of the familiarized targets, 9-month-olds were able to segment these items from fluent speech. By the age of 10.5 months, infants were able to rely solely on allophonic cues to locate the familiarized target words in passages. We consider what implications these findings have for understanding how word segmentation skills develop.

     

Critical words and the locus of stuttering in speech

The locus of stuttering in the communicative speech of 26 stutterers was studied in situations where subjects received and conveyed specific information. It was hypothesized that a larger proportion of critical rather than noncritical words would be stuttered. Critical words were those which necessarily had to be pronounced if a listener should be able to understand and act according to the messages given. The critical words were selected by the experimenter before the experiment started. The results showed that 35.8% of the critical and 8.4% of the noncritical words were stuttered. There was also significantly more stuttering on critical words than on long noncritical words. The largest proportion of critical words appeared in the final position of sentences, which was also where most stuttering was located. Whole-word repetitions, an instance of normal nonfluency, were associated with noncritical words. No correlation between frequency of stuttering and whole-word repetitions was found.     

How infants begin to extract words from speech

A crucial step for acquiring a native language vocabulary is the ability to segment words from fluent speech. English-learning infants first display some ability to segment words at about 7.5 months of age. However, their initial attempts at segmenting words only approximate those of fluent speakers of the language. In particular, 7.5-month-old infants are able to segment words that conform to the predominant stress pattern of English words. The ability to segment words with other stress patterns appears to require the use of other sources of information about word boundaries. By 10.5 months, English learners display sensitivity to additional cues to word boundaries such as statistical regularities, allophonic cues and phonotactic patterns. Infants’ word segmentation abilities undergo further development during their second year when they begin to link sound patterns with particular meanings. By 24 months, the speed and accuracy with which infants recognize words in fluent speech is similar to that of native adult listeners. This review describes how infants use multiple sources of information to locate word boundaries in fluent speech, thereby laying the foundations for language understanding.     

Phonological complexity in school-aged children who stutter and exhibit a language disorder

PurposeThe Index of Phonological Complexity and the Word Complexity Measure are two measures of the phonological complexity of a word. Other phonological measures such as phonological neighborhood density have been used to compare stuttered versus fluent words. It appears that in preschoolers who stutter, the length and complexity of the utterance is more influential than the phonetic features of the stuttered word. The present hypothesis was that in school-age children who stutter, stuttered words would be more phonologically complex than fluent words, when the length and complexity of the utterance containing them is comparable. School-age speakers who stutter were hypothesized to differ from those with a concomitant language disorder.MethodsSixteen speakers, six females and ten males (M age = 12;3; Range = 7;7 to 19;5) available from an online database, were divided into eight who had a concomitant language disorder (S + LD) and eight age- and sex-matched speakers who did not (S-Only).ResultsWhen all stuttered content words were identified, S + LD speakers produced more repetitions, and S-Only speakers produced more inaudible sound prolongations. When stuttered content words were matched to fluent content words and when talker groups were combined, stuttered words were significantly (p ≤ 0.01) higher in both the Index of Phonological Complexity and the Word Complexity Measure and lower in density (“sparser”) than fluent words.ConclusionsResults corroborate those of previous researchers. Future research directions are suggested, such as cross-sectional designs to evaluate developmental patterns of phonological complexity and stuttering plus language disordered connections.Educational objectives: The reader will be able to: (a) Define and describe phonological complexity; (b) Define phonological neighborhood density and summarize the literature on the topic; (c) Describe the Index of Phonological Complexity (IPC) for a given word; (d) Describe the Word Complexity Measure (WCM) for a given word; (e) Summarize two findings from the current study and describe how each relates to studies of phonological complexity and fluency disorders.     

Clinician's molar and molecular stuttering analyses of expanded and nonexpanded speech

Twenty speech pathologists measured total words and completed molar and molecular stuttering analyses from audio-recorded contrived samples of stuttered speech. Each subject completed a criterion referenced test prior to performing the experimental tasks. Analyses were performed under two conditions: Condition I consisted of samples presented at 100 wpm as recorded (nonexpanded); Condition II consisted of parallel samples recorded at 100 wpm as recorded (nonexpanded condition); Condition II consisted of parallel samples recorded at 100 wpm but presented at 59 wpm via a speech time expander. Results indicate that presentation of expanded samples (Condition II) significantly increased subject accuracy for the specific disfluency form-types word repetitions and part-word repetitions. Similar trends were noted for sound prolongations and hard contacts. Theoretical, experimental, and clinical implications are offered.     

Disfluencies of 3- and 5-year old Spanish-speaking children

This study examined the disfluent speech of 32 normally fluent monolingual, Spanish-speaking children from Puerto Rico. The total frequencies and types of speech disfluencies were examined in 15 children (8 girls and 7 boys) aged 3;5-4;0 years (M=3.76) and 17 children (8 girls and 9 boys) aged 5;0-5;5 years (M=5.18). When examining the total frequencies of speech disfluencies, results revealed no main effects for age or gender as well as no interactions. Moreover, no differences were observed between the age groups in most of the disfluency types, including the rank orders of the types. Revisions, interjections, and single-syllable word repetitions were the most frequently observed speech disfluencies for both age groups. Broken words, blocks, and repetitions of more than one syllable were the least frequent. Overall, results revealed both similarities and differences when compared with the reported speech behaviors of English-speaking children. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to describe: (1). the influence of age and gender on the total frequencies of speech disfluencies in 3- and 5-year old Spanish-speaking children from Puerto Rico; (2). the amount and type of difluencies in these young children; and (3). how the speech disfluencies of these Spanish-speaking children are similar to and different from those reported in the speech of English-speaking children.     

Magnitude estimation scaling judgments of speech intelligibility and speech acceptability.

20 female students in speech-language pathology provided magnitude estimation scaling responses for the speech intelligibility and acceptability of audio-taped speech samples varying systematically the number of consonant sounds produced correctly. Analysis indicated no significant over-all differences between listeners' judgments of intelligibility and acceptability; however, listeners tended to judge samples with fewer than 50% of the consonants correct as more acceptable than intelligible, and they judged samples with more than 50% consonants correct as less acceptable than intelligible.     

The perception of speech rate from the sound-silence patterns of monologues

Two experiments asked whether listeners can judge word rate from a speech signal that has been degraded in various ways. In the first, the rates of spontaneous speech were increased by 42% and further transformed to produce tone-silence sequences. The tonesilence sequences were presented to listeners who judged the rate of each sequence. Results clearly indicated that listeners could differentiate the rates of the tone-silence sequences, suggesting that minimal nonlinguistic information may be sufficient to make grossly accurate estimates of speech rates. In the second study, listeners were presented with speech sequences involving three naturally produced rates (slow, moderate, and fast) in three conditions (clear, frequency-inverted, and tone-silence) such that different listeners participated in the three conditions, but heard all rates in each condition. Listeners in the clear and frequency-inverted conditions distinguished all three rates, but those in the tone-silence condition differentiated only the slow and moderate rates. Contrary to expectation, the gender and extroversion scores of the listeners did not affect their judgments.     

How scenes containing visual errors affect speech fluency in young and older adults

We compared young and older adults’ speech during an error detection task, with some pictures containing visual errors and anomalies and other pictures error-free. We analyzed three disfluency types: mid-phrase speech fillers (e.g., It’s a little, um, girl), repetitions (e.g., He’s trying to catch the- the birds), and repairs (e.g., She- you can see her legs). Older adults produced more mid-phrase fillers than young adults only when describing pictures containing errors. These often reflect word retrieval problems and represent clear disruptions to fluency, so this interaction indicates that the need to form and maintain representations of novel information can specifically compromise older adults’ speech fluency. Overall, older adults produced more repetitions and repairs than young adults, regardless of picture type, indicating general age-related increases in these disfluencies. The obtained patterns are discussed in the context of the Transmission Deficit Hypothesis and other approaches to age-related changes in speech fluency.