Lawrence D. Shriberg

Phonological Disorders I: A Diagnostic Classification System.

Data are presented to support the validity and utility of a diagnostic classification system for persons with phonological disorders. Rationale for the classification system is developed from current reviews of issues and concepts in phonology and classification systems. The system proceeds from a worksheet for reduction of phonological and other assessment data, through five hierarchical levels of classification entries. The system will accommodate lower-level elaboration of etiological subgrouping, pending appropriate research. A retrospective classification study of 43 children with delayed speech is described. Procedural details relating classification procedures to two companion papers (Shriberg & Kwiatkowski, 1982a, 1982b) are provided.

Developmental Phonological Disorders I: A Clinical Profile

Detailed information on the speech, language, prosody, and voice characteristics of children with developmental phonological disorders is central to diverse research questions. The present study provides a clinical profile of 178 children with developmental phonological disorders. It includes information from prior reports (Shriberg & Kwiatkowski, 1982a; Shriberg, Kwiatkowski, Best, Hengst, & Terselic-Weber, 1986) and from several new measures on a sample of 64 children. The speech, prosody-voice, and causal-correlates profiles for the most recent sample are consistent with prior findings, providing a descriptive profile for forthcoming subgroup research and companion studies addressing short-term (Shriberg, Kwiatkowski, & Gruber, 1994) and long-term (Shriberg, Gruber, & Kwiatkowski, 1994) speech-sound normalization.

Reliability studies in broad and narrow phonetic transcription

A 16-category framework is proposed to review the sources of variance in studies of phonetic transcription reliability. The same framework is used to analyse transcription agreement data collected in the course of a project in child phonology, including 22 reliability estimates from five consensus transcription teams who transcribed eight subject groups. Detailed agreement data at the level of consonants, vowels and diphthongs, feature classes, and diacritics are presented for each of the 16 categories, including such traditional measurement variables as sampling mode (continuous speech; articulation tests), agreement type (intra-judge; inter-judge), and level of transcription (broad; narrow). Tabular and plotted data are deliberately presented at the lowest feasible levels for readers interested in specific questions at these levels. A total of 16 generalizations about transcription reliability are derived from descriptive and inferential statistical findings. The primary conclusion is that for certain c...

Risk Factors for Speech Delay of Unknown Origin in 3-Year-Old Children

One hundred 3-year-olds with speech delay of unknown origin and 539 same-age peers were compared with respect to 6 variables linked to speech disorders: male sex, family history of developmental communication disorder, low maternal education, low socioeconomic status (indexed by Medicaid health insurance), African American race, and prolonged otitis media. Abnormal hearing was also examined in a subset of 279 children who had at least 2 hearing evaluations between 6 and 18 months of age. Significant odds ratios were found only for low maternal education, male sex, and positive family history; a child with all 3 factors was 7.71 times as likely to have a speech delay as a child without any of these factors.

Developmental Apraxia of Speech: I. Descriptive and Theoretical Perspectives

Developmental apraxia of speech (DAS) is a putative diagnostic category for children whose speech errors presumedly (a) differ from the errors of children with developmental speech delay (SD) and (b) resemble the errors of adults with acquired apraxia of speech. The studies reported in this series (Shriberg, Aram, & Kwiatkowski, 1997a, 1997b) concern both premises, with primary focus on the first--that children with DAS can be differentiated from children with SD on the basis of one or more reliable differences in their speech error profiles. Immediate goals are to identify a diagnostic marker for DAS and to consider implications for research and clinical practice. A long-term goal is to identify the phenotype marker for DAS, on the assumption that it may be a genetically transmitted disorder. This first paper reviews relevant descriptive and theoretical perspectives. Findings from a local ascertainment study support the clinical functionality of the term suspected DAS.

Pleiotropic Effects of a Chromosome 3 Locus on Speech-Sound Disorder and Reading

Speech-sound disorder (SSD) is a complex behavioral disorder characterized by speech-sound production errors associated with deficits in articulation, phonological processes, and cognitive linguistic processes. SSD is prevalent in childhood and is comorbid with disorders of language, spelling, and reading disability, or dyslexia. Previous research suggests that developmental problems in domains associated with speech and language acquisition place a child at risk for dyslexia. Recent genetic studies have identified several candidate regions for dyslexia, including one on chromosome 3 segregating in a large Finnish pedigree. To explore common genetic influences on SSD and reading, we examined linkage for several quantitative traits to markers in the pericentrometric region of chromosome 3 in 77 families ascertained through a child with SSD. The quantitative scores measured several processes underlying speech-sound production, including phonological memory, phonological representation, articulation, receptive and expressive vocabulary, and reading decoding and comprehension skills. Model-free linkage analysis was followed by identification of sib pairs with linkage and construction of core shared haplotypes. In our multipoint analyses, measures of phonological memory demonstrated the strongest linkage (marker D3S2465, P=5.6 x 10(-5), and marker D3S3716, P=6.8 x 10(-4)). Tests for single-word decoding also demonstrated linkage (real word reading: marker D3S2465, P=.004; nonsense word reading: marker D3S1595, P=.005). The minimum shared haplotype in sib pairs with similar trait values spans 4.9 cM and is bounded by markers D3S3049 and D3S3045. Our results suggest that domains common to SSD and dyslexia are pleiotropically influenced by a putative quantitative trait locus on chromosome 3.

Developmental Apraxia of Speech: II. Toward a Diagnostic Marker

This second paper in a series on developmental apraxia of speech (DAS) (Shriberg, Aram, & Kwiatkowski, 1997a) reports findings from two studies. Study I compares speech and prosody-voice profiles of a group of 14 children with suspected DAS to profiles of 73 children with speech delay (SD). Results suggest that the only linguistic domain that differentiates some children with suspected DAS from those with SD is inappropriate stress. Study II cross-validates these findings, using retrospective data from a sample of 20 children with suspected DAS evaluated in a university phonology clinic over a 10-year period. Discussion considers methodological and conceptual issues in the measurement of linguistic stress. Theoretical issues and implications for research and clinical practice are deferred for synthesis of the present findings with those from a multi-site cross-validation project (Shriberg, Aram, & Kwiatkowski, 1997b).

Extensions to the Speech Disorders Classification System (SDCS)

This report describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). Part I describes a classification extension to the SDCS to differentiate motor speech disorders from speech delay and to differentiate among three sub-types of motor speech disorders. Part II describes the Madison Speech Assessment Protocol (MSAP), an ∼ 2-hour battery of 25 measures that includes 15 speech tests and tasks. Part III describes the Competence, Precision, and Stability Analytics (CPSA) framework, a current set of ∼ 90 perceptual- and acoustic-based indices of speech, prosody, and voice used to quantify and classify sub-types of Speech Sound Disorders (SSD). A companion paper provides reliability estimates for the perceptual and acoustic data reduction methods used in the SDCS. The agreement estimates in the companion paper support the reliability of SDCS methods and illustrate the complementary roles of perceptual and acoustic methods in diagnostic analyses of SSD of unknown origin. Examples of research using the extensions to the SDCS described in the present report include diagnostic findings for a sample of youth with motor speech disorders associated with galactosemia, and a test of the hypothesis of apraxia of speech in a group of children with autism spectrum disorders. All SDCS methods and reference databases running in the PEPPER (Programs to Examine Phonetic and Phonologic Evaluation Records) environment will be disseminated without cost when complete.

A diagnostic marker for childhood apraxia of speech: the coefficient of variation ratio

Terms such as isochrony, syllable segregation, scanning speech and staccato‐like rhythmic quality have been used to characterize the temporal regularity that may be a core feature of apraxia of speech. The present report describes a procedure to quantify temporal regularity in children with suspected apraxia of speech (sAOS). Conversational speech samples from 15 such children, together with samples from 30 3–6‐year‐old children with normal speech acquisition and 30 3–6‐year‐old children with moderate to severe speech delay of unknown origin, were selected from an audio archive. Signal processing routines were developed to identify and measure the duration of speech and pause events in 24 utterances from the speech samples of each of the 75 speakers. A value termed the coefficient of variation expressed the normalized variability in the durations of each participants speech events and pause events within each utterance. A metric termed the coefficient of variation ratio, derived by dividing the coefficient of variation for pause events by the coefficient of variation for speech events, expressed a speakers relative temporal variation in the two domains. The 15 children with sAOS had higher coefficient of variation ratios than the 30 children in each of the two comparison groups, indicating that the children with sAOS had proportionally more variation in the duration of pause events and/or less variation in the duration of speech events. Findings are interpreted as supporting the view that a constraint in speech timing is a core feature of the praxis disorder that defines a developmental form of apraxia of speech.

Encoding, memory, and transcoding deficits in Childhood Apraxia of Speech

A central question in Childhood Apraxia of Speech (CAS) is whether the core phenotype is limited to transcoding (planning/programming) deficits or if speakers with CAS also have deficits in auditory-perceptual encoding (representational) and/or memory (storage and retrieval of representations) processes. We addressed this and other questions using responses to the Syllable Repetition Task (SRT) [Shriberg, L. D., Lohmeier, H. L., Campbell, T. F., Dollaghan, C. A., Green, J. R., & Moore, C. A. (2009). A nonword repetition task for speakers with misarticulations: The syllable repetition task (SRT). Journal of Speech, Language, and Hearing Research, 52, 1189–1212]. The SRT was administered to 369 individuals in four groups: (a) typical speech–language (119), (b) speech delay–typical language (140), (c) speech delay–language impairment (70), and (d) idiopathic or neurogenetic CAS (40). CAS participants had significantly lower SRT competence, encoding, memory, and transcoding scores than controls. They were 8.3 times more likely than controls to have SRT transcoding scores below 80%. We conclude that speakers with CAS have speech processing deficits in encoding, memory, and transcoding. The SRT currently has moderate diagnostic accuracy to identify transcoding deficits, the signature feature of CAS.