Reduced duration of stuttering-like disfluencies and consistent anticipatory slowing during an adaptation task.

PURPOSE: The adaptation effect in stuttering, traditionally described as the reduction of stuttering moments over repeated readings, provides a context to investigate fluency facilitation as well as a relatively controlled means of comparing fluent speech in the immediate vicinity of words that were stuttered versus fluently produced. Acoustic studies have documented decreased duration of fluent speech during adaptation but rarely address changes in disfluencies or the speech preceding or following the disfluencies. This study addresses this gap in the research by documenting frequency and duration changes in both fluent and stuttered syllables. METHOD: Fifteen people who stutter read passages aloud five times in succession. Frequency and duration of fluent syllables, pauses, stuttering-like disfluencies (SLDs) and other disfluencies (ODs) were compared across the five readings. In addition, durations for syllables before and after pauses and SLDs were compared to determine if there were anticipation or carryover effects of SLDs on surrounding syllables. RESULTS: Durations measured for more than 22 000 fluent syllables, 1531 pauses, 128 ODs and 1752 SLDs. For most of the 15 participants, significant decreases in both frequency and duration of SLDs over the five readings were observed. In addition, lengthening of fluent syllables immediately preceding the disfluent syllables was observed: this pre-SLD lengthening did not change over the five readings. CONCLUSIONS: Decreased duration of SLDs across readings supports the motor practice hypothesis, which assumes that successive reading of the same text increases the efficiency of the speech motor plans resulting in less stuttering and decreased durations of the stuttering that persists. Pre-SLD lengthening merits further study, because it informs our knowledge of the time course of stuttered events and may be associated with conscious or unconscious anticipation of upcoming SLDs that does not decrease with motor practice. WHAT THIS PAPER ADDS: What is already known on this subject The frequency of stuttering-like disfluencies (SLDs) can be reduced using a variety of fluency-enhancing strategies. For example, the adaptation effect, in which a reduction of stuttered events occurs over repeated readings of the same material, has been widely studied. Previous studies have shown that durations of fluent syllables decrease during adaptation, supporting the hypothesis that repeated practice of the motor plan leads to increased fluency. However, temporal changes in disfluent syllables and syllables preceding and following SLDs have rarely been studied, so our understanding of the effect of motor practice on stuttering reduction is incomplete. What this study adds This study has two significant findings. First, stuttered disfluencies that persisted after the initial reading of the adaptation task tended to become shorter in duration. Fluently produced syllables and those that were stuttered, both of which are speech events related to motor control of articulators, were affected in a similar manner by the motor practice associated with adaptation. Second, lengthening of fluent syllables immediately preceding stuttered syllables was observed. This pre-stuttering lengthening, however, did not decrease in duration over the five readings: the mechanism that drives this anticipatory behaviour is not affected by repeated practice. What are the clinical implications of this work? People who stutter have neural differences that lead to speech motor planning and/or execution that is less efficient than that of typical speakers. The finding that stuttering is reduced and that persisting SLDs become shorter in duration over repeated readings provides evidence that motor practice can influence the manifestation of stuttering by temporarily making those specific motor plans more efficient. This may inform treatments for stuttering. The observation that fluent syllables immediately before SLDs were lengthened, and that this lengthening was not influenced by repeated practice, extends our understanding of the time course of stuttering events and may be useful in understanding anticipation and listener reactions to stuttering.

Speech Disorders in Children With Pompe Disease: Articulation, Resonance, and Voice Measures.

PURPOSE: Children with Pompe disease, a rare genetic metabolic myopathy, often have speech impairments. In this study, we provide a comprehensive description of articulation, resonance, and voice in children with Pompe disease. METHOD: Fifteen children with Pompe disease (11 with infantile-onset Pompe disease [IOPD], four with late-onset Pompe disease [LOPD]) ranging from 6 to 18 years of age participated in standard speech assessments. Measures included maximum tongue pressure; nasalance; cepstral peak prominence (CPP); low/high ratio (L/H ratio); diadochokinetic (DDK) rates; percent consonants correct (PCC); and visual analog scale (VAS) ratings of articulation, resonance, voice quality, and overall speech severity. Maximum tongue pressures, nasalance, CPP, L/H ratio, DDK rates, and PCC were compared to normative data from typically developing (TD) children. Correlation analyses and multiple regression models of speech measure predictors were conducted. RESULTS: Children with IOPD had greater speech impairment than those with LOPD. The IOPD group had lower maximum tongue pressures, slower articulation rates, lower PCC scores, higher nasalance, and higher L/H voice ratios than TD children. VAS ratings confirmed the presence of impaired articulatory precision, hypernasality, and dysphonia for most of the children with IOPD, with severity of impairment ratings ranging from mild to severe. The LOPD group had mildly elevated nasalance and L/H ratio values relative to TD children, and auditory-perceptual ratings suggested mild to no speech impairment. CONCLUSIONS: Speech disorders involving articulatory precision, resonance balance, and voice quality are common in children with Pompe disease, especially in those with IOPD. With improvements in the detection and treatment of Pompe disease, clinicians should be aware of the associated speech deficits.

Articulation Rate, Pauses, and Disfluencies in Professional Fighters: Potential Speech Biomarkers for Repetitive Head Injury.

OBJECTIVE: As part of a larger study dedicated to identifying speech and language biomarkers of neurological decline associated with repetitive head injury (RHI) in professional boxers and mixed martial artists (MMAs), we examined articulation rate, pausing, and disfluency in passages read aloud by participants in the Professional Athletes Brain Health Study. SETTING: A large outpatient medical center specializing in neurological care. PARTICIPANTS, DESIGN, AND MAIN MEASURES: Passages read aloud by 60 boxers, 40 MMAs, and 55 controls were acoustically analyzed to determine articulation rate (the number of syllables produced per second), number and duration of pauses, and number and duration of disfluencies in this observational study. RESULTS: Both boxers and MMAs differed from controls in articulation rate, producing syllables at a slower rate than controls by nearly half a syllable per second on average. Boxers produced significantly more pauses and disfluencies in passages read aloud than MMAs and controls. CONCLUSIONS: Slower articulation rate in both boxers and MMA fighters compared with individuals with no history of RHI and the increased occurrence of pauses and disfluencies in the speech of boxers suggest changes in speech motor behavior that may relate to RHI. These speech characteristics can be measured in everyday speaking conditions and by automatic recognition systems, so they have the potential to serve as effective, noninvasive clinical indicators for RHI-associated neurological decline.

Assessment of Dysphonia in Children with Pompe Disease Using Auditory-Perceptual and Acoustic/Physiologic Methods.

Bulbar and respiratory weakness occur commonly in children with Pompe disease and frequently lead to dysarthria. However, changes in vocal quality associated with this motor speech disorder are poorly described. The goal of this study was to characterize the vocal function of children with Pompe disease using auditory-perceptual and physiologic/acoustic methods. High-quality voice recordings were collected from 21 children with Pompe disease. The Grade, Roughness, Breathiness, Asthenia, and Strain (GRBAS) scale was used to assess voice quality and ratings were compared to physiologic/acoustic measurements collected during sustained phonation tasks, reading of a standard passage, and repetition of a short phrase at maximal volume. Based on ratings of grade, dysphonia was present in 90% of participants and was most commonly rated as mild or moderate in severity. Duration of sustained phonation tasks was reduced and shimmer was increased in comparison to published reference values for children without dysphonia. Specific measures of loudness were found to have statistically significant relationships with perceptual ratings of grade, breathiness, asthenia, and strain. Our data suggest that dysphonia is common in children with Pompe disease and primarily reflects impairments in respiratory and laryngeal function; however, the primary cause of dysphonia remains unclear. Future studies should seek to quantify the relative contribution of deficits in individual speech subsystems on voice quality and motor speech performance more broadly.

Exploring the Acoustic Perceptual Relationship of Speech in Parkinson's Disease.

Purpose Auditory perceptual judgments are commonly used to diagnose dysarthria and assess treatment progress. The purpose of the study was to examine the acoustic underpinnings of perceptual speech abnormalities in individuals with Parkinson's disease (PD). Method Auditory perceptual judgments were obtained from sentences produced by 13 speakers with PD and five healthy older adults. Twenty young listeners rated overall ease of understanding, articulatory precision, voice quality, and prosodic adequacy on a visual analog scale. Acoustic measures associated with the speech subsystems of articulation, phonation, and prosody were obtained, including second formant transitions, articulation rate, cepstral and spectral measures of voice, and pitch variations. Regression analyses were performed to assess the relationships between perceptual judgments and acoustic variables. Results Perceptual impressions of Parkinsonian speech were related to combinations of several acoustic variables. Approximately 36%-49% of the variance in the perceptual ratings were explained by the acoustic measures indicating a modest acoustic perceptual relationship. Conclusions The relationships between perceptual ratings and acoustic signals in Parkinsonian speech are multifactorial and involve a variety of acoustic features simultaneously. The modest acoustic perceptual relationships, however, suggest that future work is needed to further examine the acoustic bases of perceptual judgments in dysarthria.

Acoustic characteristics in relation to intelligibility reduction in noise for speakers with Parkinson's disease.

Decreased speech intelligibility in noisy environments is frequently observed in speakers with Parkinson's disease (PD). This study investigated which acoustic characteristics across the speech subsystems contributed to poor intelligibility in noise for speakers with PD. Speech samples were obtained from 13 speakers with PD and five healthy controls reading 56 sentences. Intelligibility analysis was conducted in quiet and noisy listening conditions. Seventy-two young listeners transcribed the recorded sentences in quiet and another 72 listeners transcribed in noise. The acoustic characteristics of the speakers with PD who experienced large intelligibility reduction from quiet to noise were compared to those with smaller intelligibility reduction in noise and healthy controls. The acoustic measures in the study included second formant transitions, cepstral and spectral measures of voice (cepstral peak prominence and low/high spectral ratio), pitch variation, and articulation rate to represent speech components across speech subsystems of articulation, phonation, and prosody. The results show that speakers with PD who had larger intelligibility reduction in noise exhibited decreased second formant transition, limited cepstral and spectral variations, and faster articulation rate. These findings suggest that the adverse effect of noise on speech intelligibility in PD is related to speech changes in the articulatory and phonatory systems.

Predicting Intelligibility Deficits in Parkinson's Disease With Perceptual Speech Ratings.

Purpose This study investigated whether perceptual ratings of speech parameters were predictive of transcription intelligibility in quiet and in noise for speakers with Parkinson's disease (PD). Method Ten speakers with PD and five healthy controls read 56 sentences. One group of 60 listeners orthographically transcribed the sentences in quiet, and another group of 60 listeners transcribed in noise. An additional 23 listeners judged a variety of speech parameters, including articulation, prosody, resonance, voice quality, and ease of understanding on a visual analog scale. Scores of the visual analog scale ratings were regressed against transcription intelligibility in quiet and in noise. Results Perceptual ratings of all the speech parameters were lower for speakers with PD. Global speech understanding, indexed by ease of understanding ratings, was associated with transcription intelligibility in quiet and in noise with a stronger effect in noise. Among the rated speech parameters, ease of understanding and voice quality ratings were significant predictors of speech intelligibility in noise. Conclusions Speech in individuals with PD was more difficult for listeners to understand and was characterized by deficits in articulation, prosody, resonance, and voice quality compared to normal speech produced by healthy older adults. Ease of understanding ratings, even when performed in quiet, predicted intelligibility in noise. Poor voice quality ratings in PD, a sign of phonatory deficit, had a negative impact on intelligibility in noise for speakers with PD.

Muscle weakness and speech in oculopharyngeal muscular dystrophy.

PURPOSE: We documented speech and voice characteristics associated with oculopharyngeal muscular dystrophy (OPMD). Although it is a rare disease, OPMD offers the opportunity to study the impact of myopathic weakness on speech production in the absence of neurologic deficits in a relatively homogeneous group of speakers. METHODS: Twelve individuals with OPMD and 12 healthy age-matched controls underwent comprehensive assessment of the speech mechanism including spirometry (respiratory support), nasometry (resonance balance), phonatory measures (pitch, loudness, and quality), articulatory measures (diadochokinetic rates, segment duration measures, spectral moments, and vowel space), tongue-to-palate strength measures during maximal isometric and speechlike tasks, quality-of-life questionnaire, and perceptual speech ratings by listeners. RESULTS: Individuals with OPMD had substantially reduced tongue strength compared to the controls. However, little impact on speech and voice measures or on speech intelligibility was observed except for slower diadochokinetic rates. CONCLUSIONS: Despite having less than half the maximal tongue strength of healthy controls, the individuals with OPMD exhibited minimal speech deficits. The threshold of weakness required for noticeable speech impairment may not have been reached by this group of adults with OPMD.

Is tongue strength an important influence on rate of articulation in diadochokinetic and reading tasks?

PURPOSE: The purpose of this study was to assess the relationship between tongue strength and rate of articulation in 2 speech tasks, diadochokinetic rates and reading aloud, in healthy men and women between 20 and 78 years of age. METHOD: Diadochokinetic rates were measured for the syllables /p/, /t/, /k/, and /ptk/, and articulation rates were calculated for a reading of the Rainbow Passage for 57 adult volunteers. The Iowa Oral Performance Instrument (LLC Northwest) was used to obtain maximum tongue pressure, tongue pressure exerted during production of /t/, and tongue endurance. Correlation analyses were performed to determine the relation among articulation rate and tongue pressure and endurance measures. RESULTS: Maximum tongue pressure, the pressure used to produce /t/, the proportion of maximum pressure used to produce /t/, and tongue endurance were poor predictors of diadochokinetic rates and articulation rate in reading for healthy speakers. Discussion Focus must remain on factors beyond strength, such as movement precision and coordination, to improve researchers' understanding of normal and disordered speech production in adults.

Swallow characteristics in patients with oculopharyngeal muscular dystrophy.

PURPOSE: This prospective investigation evaluates oral weakness and its impact on swallow function, weight, and quality of life in patients with oculopharyngeal muscular dystrophy (OPMD). METHOD: Intraoral pressure, swallow pressure, and endurance were measured using an Iowa Oral Performance Instrument in participants with OPMD and matched controls. Timed water swallow, weight, and quality of life were also assessed. RESULTS: Participants with OPMD were weaker than controls. Oral weakness impacted strength, swallow pressure, swallow capacity, swallow volume, swallow time, and quality of life. Tongue endurance was not affected by oral weakness. CONCLUSION: This investigation provides further insight into the swallow function of patients with myopathic disease. Muscle fiber loss leads to weakness, which results in reductions in swallow function and quality of life. Weight and endurance are not greatly altered.

Effects of loud and amplified speech on sentence and word intelligibility in Parkinson disease.

PURPOSE: In the two experiments in this study, the author examined the effects of increased vocal effort (loud speech) and amplification on sentence and word intelligibility in speakers with Parkinson disease (PD). Methods Five talkers with PD produced sentences and words at habitual levels of effort and using loud speech techniques. Amplified sets of sentences and words were created by increasing the intensity of habitual stimuli to the level of loud stimuli. Listeners rated the intelligibility of the 3 sets of sentences on a 1-7 scale and transcribed the 3 sets of words. RESULTS: Both loud speech and amplification significantly improved intelligibility for sentences and words. Loud speech resulted in greater intelligibility improvement than amplification. CONCLUSIONS: By comparing loud and amplified scores, about one third to one half of intelligibility improvement with loud speech could be attributed to increases in audibility or signal-to-noise ratio. Thus, factors other than increased intensity must be partly responsible for the loud speech benefit. Changes in articulation appear to play a relatively small role: Initial/h/was the only consonant to consistently show improvement with loud speech. Phonatory changes such as improvements in F(0) and spectral tilt may account for improved speech intelligibility using loud speech techniques.

Vowel space characteristics and vowel identification accuracy.

PURPOSE: To examine the relation between vowel production characteristics and intelligibility. METHOD: Acoustic characteristics of 10 vowels produced by 45 men and 48 women from the J. M. Hillenbrand, L. A. Getty, M. J. Clark, and K. Wheeler (1995) study were examined and compared with identification accuracy. Global (mean f0, F1, and F2; duration; and amount of formant movement) and fine-grained measures (vowel space area; mean distance among vowels; f0, F1, and F2 ranges; duration ratio between long and short vowels; and formant movement ratio between dynamic and static vowels) were used to predict identification scores. Acoustic measures of the most frequently confused pairs (/ae/-/epsilon/ and /a/-/inverted v/) were compared. RESULTS: Global and fine-grained measures accounted for less than 1/4 of variance in identification scores: Vowel space area alone accounted for 9%-12% of variance. Differences in vowel identification were largely due to poor identification of /ae/, /epsilon/, /a/, or /inverted v/. Well-identified vowels were distinctive in formant frequencies, duration, and amount of formant movement over time. CONCLUSIONS: Distinctiveness among neighboring vowels is more important in determining vowel intelligibility than vowel space area. Acoustic comparison of confused vowels may be more useful in studying intelligibility of normal and disordered speech than in measuring vowel space area.

Effects of a sour bolus on the intramuscular electromyographic (EMG) activity of muscles in the submental region.

A sour bolus has been used as a modality in the treatment of oropharyngeal dysphagia based on the hypothesis that this stimulus provides an effective preswallow sensory input that lowers the threshold required to trigger a pharyngeal swallow. The result is a more immediate swallow onset time. Additionally, the sour bolus may invigorate the oral muscles resulting in stronger contractions during the swallow. The purpose of this investigation was to compare the intramuscular electromyographic activity of the mylohyoid, geniohyoid, and anterior belly of the digastric muscles during sour and water boluses with regard to duration, strength, and timing of muscle activation. Muscle duration, swallow onset time, and pattern of muscle activation did not differ for the two bolus types. Muscle activation time was more tightly approximated across the onsets of the three muscles when a sour bolus was used. A sour bolus also resulted in a stronger muscle contraction as evidenced by greater electromyographic activity. These data support the use of a sour bolus as part of a treatment paradigm.