Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants.

The anatomic basis and articulatory features of speech production are often studied with imaging studies that are typically acquired in the supine body position. It is important to determine if changes in body orientation to the gravitational field alter vocal tract dimensions and speech acoustics. The purpose of this study was to assess the effect of body position (upright versus supine) on (1) oral and pharyngeal measurements derived from acoustic pharyngometry and (2) acoustic measurements of fundamental frequency (F0) and the first four formant frequencies (F1-F4) for the quadrilateral point vowels. Data were obtained for 27 male and female participants, aged 17 to 35 yrs. Acoustic pharyngometry showed a statistically significant effect of body position on volumetric measurements, with smaller values in the supine than upright position, but no changes in length measurements. Acoustic analyses of vowels showed significantly larger values in the supine than upright position for the variables of F0, F3, and the Euclidean distance from the centroid to each corner vowel in the F1-F2-F3 space. Changes in body position affected measurements of vocal tract volume but not length. Body position also affected the aforementioned acoustic variables, but the main vowel formants were preserved.

Inter-relationships of functional status in cerebral palsy: analyzing gross motor function, manual ability, and communication function classification systems in children.

AIM: To investigate the relationships among the Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS), and Communication Function Classification System (CFCS) in children with cerebral palsy (CP). METHOD: Using questionnaires describing each scale, mothers reported GMFCS, MACS, and CFCS levels in 222 children with CP aged from 2 to 17 years (94 females, 128 males; mean age 8 y, SD 4). Children were referred from pediatric developmental/behavioral, physiatry, and child neurology clinics, in the USA, for a case-control study of the etiology of CP. Pairwise relationships among the three systems were assessed using Spearman's correlation coefficients (r(s) ), stratifying by age and CP topographical classifications. RESULTS: Correlations among the three functional assessments were strong or moderate. GMFCS levels were highly correlated with MACS levels (r(s) = 0.69) and somewhat less so with CFCS levels (r(s) = 0.47). MACS and CFCS were also moderately correlated (r(s) = 0.54). However, many combinations of functionality were found. Of the 125 possible combinations of the three five-point systems, 62 were found in these data. INTERPRETATION: Use of all three classification systems provides a more comprehensive picture of the child's function in daily life than use of any one alone. This resulting functional profile can inform both clinical and research purposes.

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 maturational gradient of infant vocalizations: Developmental stages and functional modules.

Stage models have been influential in characterizing infant vocalizations in the first year of life. These models are basically descriptive and do not explain why certain types of vocal behaviors occur within a particular stage or why successive patterns of vocalization occur. This review paper summarizes and elaborates a theory of Developmental Functional Modules (DFMs) and discusses how maturational gradients in the DFMs explain age typical vocalizations as well as the transitions between successive stages or other static forms. Maturational gradients are based on biological processes that effect the reconfiguration and remodeling of the respiratory, laryngeal, and craniofacial systems during infancy. From a dynamic systems perspective, DFMs are part of a complex system with multiple degrees of freedom that can achieve stable performance with relatively few control variables by relying on principles such as synergies, self-organization, nonlinear performance, and movement variability.

Retrospective Case-Control Study of Communication and Motor Abilities in 143 Children With Suspected Childhood Apraxia of Speech: Effect of Concomitant Diagnosis.

Purpose: This study sought to determine if children with childhood apraxia of speech (CAS) plus another major diagnosis (CAS+) are equivalent in communication and motor profiles to those with a primary diagnosis of CAS and no indication or report of any other diagnosis (CAS-Primary). Method: This retrospective case-control study included a chart review of 143 children who were suspected of having CAS at Children's Hospital-Wisconsin between 1998 and 2004. Participants were between 30 and 127 months old and included 107 males. Participants were assigned to the suspected CAS-Primary group (n = 114) if they had characteristics of CAS but no other major diagnosis (e.g., galactosemia) and to the CAS+ group (n = 29) if a comorbid diagnosis was present. Groups were compared across demographic, communication, and motor characteristics. Results: Children with CAS+ evidenced more severe motor profiles than those with CAS-Primary, χ2 = (1, n = 122) = 4.952, p = .026, and a small-to-medium effect size (Φ = .201). On average, communication profiles also tended to be more severe among those with CAS+ wherein receptive language was poorer and phonemic inventories were smaller than those with CAS-Primary. Conclusions: These retrospective data suggest that comorbid diagnosis may play an important role in communication and motor development in children with suspected CAS. These exploratory findings should motivate future prospective studies that consider the role of concomitant diagnoses in symptom profile and response to treatment in children with CAS.

Oral and Laryngeal Diadochokinesis Across the Life Span: A Scoping Review of Methods, Reference Data, and Clinical Applications.

PURPOSE: The aim of this study was to conduct a scoping review of research on oral and laryngeal diadochokinesis (DDK) in children and adults, either typically developing/developed or with a clinical diagnosis. METHOD: Searches were conducted with PubMed/MEDLINE, Google Scholar, CINAHL, and legacy sources in retrieved articles. Search terms included the following: DDK, alternating motion rate, maximum repetition rate, sequential motion rate, and syllable repetition rate. RESULTS: Three hundred sixty articles were retrieved and included in the review. Data source tables for children and adults list the number and ages of study participants, DDK task, and language(s) spoken. Cross-sectional data for typically developing children and typically developed adults are compiled for the monosyllables /pʌ/, /tʌ/, and /kʌ/; the trisyllable /pʌtʌkʌ/; and laryngeal DDK. In addition, DDK results are summarized for 26 disorders or conditions. DISCUSSION: A growing number of multidisciplinary reports on DDK affirm its role in clinical practice and research across the world. Atypical DDK is not a well-defined singular entity but rather a label for a collection of disturbances associated with diverse etiologies, including motoric, structural, sensory, and cognitive. The clinical value of DDK can be optimized by consideration of task parameters, analysis method, and population of interest.

Developmental Functional Modules in Infant Vocalizations.

Purpose Developmental functional modules (DFMs) are biological modules that are defined by their structural (morphological), functional, or developmental elements, and, in some cases, all three of these. This review article considers the hypothesis that vocal development in the first year of life can be understood in large part with respect to DFMs that characterize the speech production system. Method Literature is reviewed on relevant embryology, orofacial reflexes, craniofacial muscle properties, stages of vocal development, and related topics to identity candidates for DFMs. Results The following DFMs are identified and described: laryngeal, pharyngo-laryngeal, mandibular, velopharyngeal, labial complex, and lingual complex. These DFMs and their submodules, considered along with phenomena such as rhythmic movements, account for several well-documented features of vocal development in the first year of life. The proposed DFMs, rooted in embryologic, histologic, and kinematic properties, serve as low-dimensional control variables for the developing vocal tract. Each DFM is semi-autonomous but interacts with other DFMs to produce patterns of vocal behavior. Discussion Considered in relation to contemporary profiles and models of vocal development in the first year of life, DFMs have interpretive and explanatory value. DFMs complement other approaches in the study of infant vocalizations and are grounded in biology.

Breath group analysis for reading and spontaneous speech in healthy adults.

AIMS: The breath group can serve as a functional unit to define temporal and fundamental frequency (f0) features in continuous speech. These features of the breath group are determined by the physiologic, linguistic, and cognitive demands of communication. Reading and spontaneous speech are two speaking tasks that vary in these demands and are commonly used to evaluate speech performance for research and clinical applications. The purpose of this study is to examine differences between reading and spontaneous speech in the temporal and f0 aspects of their breath groups. METHODS: Sixteen participants read two passages and answered six questions while wearing a circumferentially vented mask connected to a pneumotach. The aerodynamic signal was used to identify inspiratory locations. The audio signal was used to analyze task differences in breath group structure, including temporal and f0 components. RESULTS: The main findings were that spontaneous speech task exhibited significantly more grammatically inappropriate breath group locations and longer breath group duration than did the passage reading task. CONCLUSION: The task differences in the percentage of grammatically inadequate breath group locations and in breath group duration for healthy adult speakers partly explain the differences in cognitive-linguistic load between the passage reading and spontaneous speech.

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.

What Acoustic Studies Tell Us About Vowels in Developing and Disordered Speech.

Purpose Literature was reviewed on the development of vowels in children's speech and on vowel disorders in children and adults, with an emphasis on studies using acoustic methods. Method Searches were conducted with PubMed/MEDLINE, Google Scholar, CINAHL, HighWire Press, and legacy sources in retrieved articles. The primary search items included, but were not limited to, vowels, vowel development, vowel disorders, vowel formants, vowel therapy, vowel inherent spectral change, speech rhythm, and prosody. Results/Discussion The main conclusions reached in this review are that vowels are (a) important to speech intelligibility; (b) intrinsically dynamic; (c) refined in both perceptual and productive aspects beyond the age typically given for their phonetic mastery; (d) produced to compensate for articulatory and auditory perturbations; (e) influenced by language and dialect even in early childhood; (f) affected by a variety of speech, language, and hearing disorders in children and adults; (g) inadequately assessed by standardized articulation tests; and (h) characterized by at least three factors-articulatory configuration, extrinsic and intrinsic regulation of duration, and role in speech rhythm and prosody. Also discussed are stages in typical vowel ontogeny, acoustic characterization of rhotic vowels, a sensory-motor perspective on vowel production, and implications for clinical assessment of vowels.

Anatomic development of the oral and pharyngeal portions of the vocal tract: an imaging study.

The growth of the vocal tract (VT) is known to be non-uniform insofar as there are regional differences in anatomic maturation. This study presents quantitative anatomic data on the growth of the oral and pharyngeal portions of the VT from 605 imaging studies for individuals between birth and 19 years. The oral (horizontal) portion of the VT was segmented into lip-thickness, anterior-cavity-length, oropharyngeal-width, and VT-oral, and the pharyngeal (vertical) portion of the VT into posterior-cavity-length, and nasopharyngeal-length. The data were analyzed to determine growth trend, growth rate, and growth type (neural or somatic). Findings indicate differences in the growth trend of segments/variables analyzed, with significant sex differences for all variables except anterior-cavity-length. While the growth trend of some variables displays prepubertal sex differences at specific age ranges, the importance of such localized differences appears to be masked by overall growth rate differences between males and females. Finally, assessment of growth curve type indicates that most VT structures follow a combined/hybrid (somatic and neural) growth curve with structures in the vertical plane having a predominantly somatic growth pattern. These data on the non-uniform growth of the vocal tract reveal anatomic differences that contribute to documented acoustic differences in prepubertal speech production.

Analysis of diadochokinesis in ataxic dysarthria using the motor speech profile program.

AIMS: The Diadochokinetic Rate Analysis (DRA) in the KayPENTAX Motor Speech Profile is a computer program for the analysis of diadochokinesis (DDK). The objective of this study is to evaluate the suitability, reliability, and concurrent validity of the results from the DRA protocol and hand measurement for individuals with ataxic dysarthria, which is characteristically associated with dysdiadochokinesis. METHODS: Twenty-one participants with ataxic dysarthria were recorded as they repeated various syllables as quickly and steadily as possible. The DDK samples were executed by the DRA protocol at different thresholds and were also hand-measured. Analyses were based on the percentage of nonexecutable DDK samples, defined as samples in which the lowest peak intensity during CV syllables is lower than the highest peak intensity during intersyllable pauses, and the comparisons of the results between repeated analyses at different thresholds and between automatic and manual measuring methods. RESULTS: (1) More than one third of the DDK samples were nonexecutable; (2) the reliability at different thresholds and concurrent validity between different measuring methods were both satisfactory, and (3) temporal variation parameters were more inconsistent between different measuring methods than intensity variation parameters. CONCLUSION: DRA has notable limitations in its clinical application but there is a considerable potential for improving its performance.

Auditory-Perceptual Assessment of Fluency in Typical and Neurologically Disordered Speech.

Purpose: The aim of this study is to investigate how speech fluency in typical and atypical speech is perceptually assessed by speech-language pathologists (SLPs). Our research questions were as follows: (a) How do SLPs rate fluency in speakers with and without neurological communication disorders? (b) Do they differentiate the speaker groups? and (c) What features do they hear impairing speech fluency? Method: Ten SLPs specialized in neurological communication disorders volunteered as expert judges to rate 90 narrative speech samples on a Visual Analogue Scale (see Kempster, Gerratt, Verdolini Abbott, Barkmeier-Kraemer, & Hillman, 2009; p. 127). The samples-randomly mixed-were from 70 neurologically healthy speakers (the control group) and 20 speakers with traumatic brain injury, 10 of whom had neurogenic stuttering (designated as Clinical Groups A and B). Results: The fluency rates were higher for typical speakers than for speakers with traumatic brain injury; however, the agreement among the judges was higher for atypical fluency. Auditory-perceptual assessment of fluency was significantly impaired by the features of stuttering and something else but not by speech rate. Stuttering was also perceived in speakers not diagnosed as stutterers. A borderline between typical and atypical fluency was found. Conclusions: Speech fluency is a multifaceted phenomenon, and on the basis of this study, we suggest a more general approach to fluency and its deviations that will take into account, in addition to the motor and linguistic aspects of fluency, the metalinguistic component of expression as well. The results of this study indicate a need for further studies on the precise nature of borderline fluency and its different disfluencies.

Single-Word Speech Intelligibility in Children and Adults With Down Syndrome.

Purpose: A single-word identification test was used to study speech production in children and adults with Down syndrome (DS) to determine the developmental pattern of speech intelligibility with an emphasis on vowels. Method: Speech recordings were collected from 62 participants with DS aged 4-40 years and 25 typically developing participants aged 4-7 years. Panels of 5 adult lay listeners transcribed the speech recordings orthographically, and their responses were scored in comparison with the speakers' target words. Results: Speech intelligibility in persons with DS improved with age, especially between the ages of 4 and 16 years. Whereas consonants contribute to intelligibility, vowels also played an important role in reduced intelligibility with an apparent developmental difference in low versus high vowels, where the vowels /æ/ and/ɑ/ developed at a later age than /i/ and /u/. Interspeaker variability was large, with male individuals being generally less intelligible than female individuals and some adult men having very low intelligibility. Conclusion: Results show age-related patterns in speech intelligibility in persons with DS and identify the contribution of dimensions of vowel production to intelligibility. The methods used clarify the phonetic basis of reduced intelligibility, with implications for assessment and treatment.

Dysarthria in Mandarin-Speaking Children With Cerebral Palsy: Speech Subsystem Profiles.

Purpose: This study explored the speech characteristics of Mandarin-speaking children with cerebral palsy (CP) and typically developing (TD) children to determine (a) how children in the 2 groups may differ in their speech patterns and (b) the variables correlated with speech intelligibility for words and sentences. Method: Data from 6 children with CP and a clinical diagnosis of moderate dysarthria were compared with data from 9 TD children using a multiple speech subsystems approach. Acoustic and perceptual variables reflecting 3 speech subsystems (articulatory-phonetic, phonatory, and prosodic), and speech intelligibility, were measured based on speech samples obtained from the Test of Children's Speech Intelligibility in Mandarin (developed in the lab for the purpose of this research). Results: The CP and TD children differed in several aspects of speech subsystem function. Speech intelligibility scores in children with CP were influenced by all 3 speech subsystems, but articulatory-phonetic variables had the highest correlation with word intelligibility. All 3 subsystems influenced sentence intelligibility. Conclusion: Children with CP demonstrated deficits in speech intelligibility and articulation compared with TD children. Better speech sound articulation influenced higher word intelligibility, but did not benefit sentence intelligibility.

Early Predictors and Correlates of Communication Function in Children With Cerebral Palsy.

Birth characteristics and developmental milestones were evaluated as early predictors/correlates of communication in children with cerebral palsy. The hypothesis was that maternal report of child's age for vocal play and first words would predict current functional communication. A case series of 215 children, 2 to 17 years (mean age = 8.2 years, SD = 3.9) with cerebral palsy was recruited from medical practices in 3 Michigan cities. Early developmental data were collected by maternal interview. The child's Communication Function Classification System (CFCS) level was obtained from parent. Predictors of less functional communication included gestational age >32 weeks, number of comorbidities, age of first words after age 24 months, and use of communication methods other than speech. Several birth characteristics and developmental language milestones were predictive of later communication performance for children with cerebral palsy. These characteristics and milestones should trigger referrals for communication evaluations, including speech, language, hearing, and/or augmentative and alternative communication.

Vowel acoustic space development in children: a synthesis of acoustic and anatomic data.

PURPOSE: This article integrates published acoustic data on the development of vowel production. Age specific data on formant frequencies are considered in the light of information on the development of the vocal tract (VT) to create an anatomic-acoustic description of the maturation of the vowel acoustic space for English. METHOD: Literature searches identified 14 studies reporting data on vowel formant frequencies. Data on corner vowels are summarized graphically to show age- and sex- related changes in the area and shape of the traditional vowel quadrilateral. CONCLUSIONS: Vowel development is expressed as follows: (a) establishment of a language-appropriate acoustic representation (e.g., F1-F2 quadrilateral or F1-F2-F3 space), (b) gradual reduction in formant frequencies and F1-F2 area with age, (c) reduction in formant-frequency variability, (d) emergence of male-female differences in formant frequency by age 4 years with more apparent differences by 8 years, (e) jumps in formant frequency at ages corresponding to growth spurts of the VT, and (f) a decline of f0 after age 1 year, with the decline being more rapid during early childhood and adolescence. Questions remain about optimal procedures for VT normalization and the exact relationship between VT growth and formant frequencies. Comments are included on nasalization and vocal fundamental frequency as they relate to the development of vowel production.

Evidence-based practice in communication disorders: progress not perfection.

PURPOSE: This commentary is written in response to a companion paper by Nan Bernstein Ratner (Evidence-Based Practice: An Examination of its Ramifications for the Practice of Speech-Language Pathology). METHOD: The comments reflect my experience as Vice President for Research and Technology of the American Speech-Language-Hearing Association (ASHA). One of the responsibilities of the Vice President is to monitor the work of the Advisory Committee on Evidence-Based Practice. CONCLUSION: Evidence-based practice (EBP) is a challenging but attainable goal for audiology and speech-language pathology. Our professions have made rapid progress in developing the foundations for EBP. To be sure, a great deal of work remains to be done, but we have learned from the experiences of other professions and have built our own systems to support EBP.

Optimizing Vowel Formant Measurements in Four Acoustic Analysis Systems for Diverse Speaker Groups.

PURPOSE: This study systematically assessed the effects of select linear predictive coding (LPC) analysis parameter manipulations on vowel formant measurements for diverse speaker groups using 4 trademarked Speech Acoustic Analysis Software Packages (SAASPs): CSL, Praat, TF32, and WaveSurfer. METHOD: Productions of 4 words containing the corner vowels were recorded from 4 speaker groups with typical development (male and female adults and male and female children) and 4 speaker groups with Down syndrome (male and female adults and male and female children). Formant frequencies were determined from manual measurements using a consensus analysis procedure to establish formant reference values, and from the 4 SAASPs (using both the default analysis parameters and with adjustments or manipulations to select parameters). Smaller differences between values obtained from the SAASPs and the consensus analysis implied more optimal analysis parameter settings. RESULTS: Manipulations of default analysis parameters in CSL, Praat, and TF32 yielded more accurate formant measurements, though the benefit was not uniform across speaker groups and formants. In WaveSurfer, manipulations did not improve formant measurements. CONCLUSIONS: The effects of analysis parameter manipulations on accuracy of formant-frequency measurements varied by SAASP, speaker group, and formant. The information from this study helps to guide clinical and research applications of SAASPs.

Breath-group intelligibility in dysarthria: characteristics and underlying correlates.

PURPOSE: This study was designed to determine whether within-speaker fluctuations in speech intelligibility occurred among speakers with dysarthria who produced a reading passage, and, if they did, whether selected linguistic and acoustic variables predicted the variations in speech intelligibility. METHOD: Participants with dysarthria included a total of 10 persons with Parkinson's disease and amyotrophic lateral sclerosis; a control group of 10 neurologically normal speakers was also studied. Each participant read a passage that was subsequently separated into consecutive breath groups for estimates of individual breath group intelligibility. Sixty listeners participated in 2 perceptual experiments, generating intelligibility scores across speakers and for each breath group produced by speakers with dysarthria. RESULTS: Individual participants with dysarthria had fluctuations in intelligibility across breath groups. Breath groups of participants with dysarthria had fewer average words and reduced interquartile ranges for the 2nd formant, the latter a global measure of articulatory mobility. Regression analyses with intelligibility measures as the criterion variable and linguistic and acoustic measures as predictor variables produced significant functions both within and across speakers, but the solutions were not the same. CONCLUSIONS: Linguistic or acoustic variables that predict across-speaker variations in speech intelligibility may not function in the same way when within-speaker variations in intelligibility are considered.