1. A perceptual investigation of prosodic accuracy in children with typical language and specific language impairment
Peter Richtsmeier Lisa Goffman Purdue University
Research supported by Grant #R03DC to Peter Richtsmeier
BBTOP scores are potentially a big deal.
Rating Scale
Dependent Measures
Ratings on a perceptual scale of foot stress from 1 (iambic) to 5 (trochaic)
Number of Repetitions needed to make each rating
Number of Unexpected Ratings, or ratings that did not match the prosodic category (iamb or trochee) of the adult model
Overall Design: 3 × 2 × 3
Language Groups (Adults, SLI, TD) by Prosodic Groups (Iambs, Trochees) by Word Locations (2-syllable words, First 2 of 4 syllables, Last 2 of 4 syllables) 1 2 3 4 5
Iambic
Weakly Iambic
Neither
Weakly Trochaic
Trochaic
Background on Production of Within-Word Stress Contours
Children with typical language development (TD):
One- and two-year-old children often omit unstressed syllables [2]
Children must learn to shorten unstressed vowels [1, 4, 5]
One- and two-year-olds use F0, amplitude, and duration to mark stress in their speech [4], often inconsistently [5]
Children with language impairments, including specific language impairment (SLI):
Omit unstressed syllables, especially grammatical morphemes, into preschool age. [2]
Differ from TD peers in both the acoustic and articulatory expression of within-word stress. [3]
Perceptually-based standardized tests have been investigated for SLI [6] and for childhood apraxia of speech [7] with some success.
Speakers and Raters
Child Speakers
Adult Speakers – 8 adult females, native English speakers, normal speech and hearing
Adult Raters – 12 adults, native English speakers, normal speech and hearing. Nine were female. All were enrolled in the clinical SLP graduate program at Purdue University.
Group N
Age Range **
SPELT
PPC
* †
BBTOP
PPVT-4
EVT *
CMMS
SLI 8
4;5 – 5;6
81.6
61.5
77.4
106.8
97.3
109.6 TD
3;8 - 5;8
116.1
82.3
101.0
107.5
112.3
116.6
For one-tailed t-tests, ** indicates p < .01, * indicates p < .05, † BBTOP scores for 4/8 TD children.
For children with TD, all passed the SPELT and 4/8 were given and passed the BBTOP. For children with SLI, none passed the SPELT and 5/8 did not pass the BBTOP.
Results
Ratings Repetitions Unexpected
Ratings
Materials
Target Word Types
Words Adults
Produced
Words Children Produced
2-syl Trochaic
re.də
ti.də
do.sə
po.fə
4-syl Trochaic
do.lə.re.sə
so.lə.ti.rə
la.tə.so.rə
mi.fə.po.bə
2-syl Iambic
lə.do
tə.re
sə.la
bə.mi
4-syl Iambic
də.ti.rə.la
rə.so.tə.do
tə.la.sə.re
pə.fa.mə.be
Outstanding Questions
When all syllables are present, does the production of stress by children with SLI still differ markedly from children with TD and adults?
Do adults, children with SLI, and children with TD differ in production of within-word stress depending on whether the word is iambic (e.g., ‘giraffe’) or trochaic (e.g., ‘pencil’)?
Do children with SLI have difficulty producing stress in longer, phonologically complicated words?
Iambs Trochees Histograms
Token Counts and Missing Productions
One production of each of 16 words was taken from each adult speaker. Up to 4 (out of 9 original) productions of each of 4 words were taken from each child speaker. Productions that included phonetic errors, for example [pa.mi] instead of [bə.mi], were included from children. However, children’s productions needed to include the same number of syllables as appeared in the adults words, so [fa.mə.be] instead of [pə.fa.mə.be] was not included. The figure to the right shows the number of missing syllables from the original production data, organized by language group and word type. The N values are the number of children who contributed to the totals.
Conclusions
Adults were given far more prototypical ratings, with fewer repetitions, and with fewer unexpected ratings than either the TD or SLI groups, suggesting immature prosodic development in both groups of children.
Across the dependent variables, children with SLI differed significantly from their TD peers on iambic words, suggesting an area of relative weakness.
Stress contour production by children with SLI did not appear any worse in four-syllable words compared to two-syllable words.
References
Overview of Method
The study had two parts:
As part of a larger ongoing study, productions of nonsense words with alternating stress patterns were collected from children with TD and children with SLI. Adult productions served as models in this larger study.
Here, twelve adult raters with phonetic training judged child and adult productions for prosodic prototypicality.
Procedure
One rating for each two-syllable word and two ratings for each four-syllable word; one for each two-syllable part. For example, [pə.fa] and [mə.be].
Raters could listen to each word any number of times before making a rating.
Productions were blocked by speaker, and the two parts of four-syllable words were always in succession. Word order within a speaker block and speaker order were randomized.
[1]. Allen, G., & Hawkins, S. (1980). Phonological rhythm: Definition and development. In G. Yeni-Komshian, J. Kavanagh, & G. Ferguson (Eds.), Child Phonology, Vol I: Production. New York: Academic Press.
[2]. Gerken, L. A. & McGregor, K. (1998). An Overview of Prosody and Its Role in Normal and Disordered Child Language. Am J Sp Lang Pathol, 7;38-48.
[3]. Goffman, L. (1999). Prosodic influences on speech production in children with specific language impairment and speech deficits: Kinematic, acoustic, and transcription evidence. JSLHR, 42,
[4]. Kehoe, M., Stoel-Gammon, C., & Buder, E. H. (1995). Acoustic correlates of stress in young children's speech, JSLHR, 38,
[5]. Pollock, K. E., Brammer, D. M., & Hageman, C. F. (1993). An acoustic analysis of young children’s productions of word stress. Journal of Phonetics, 21, 183–203.
[6]. Samuelsson, L., Scocco, C. & Nettelbladt, U. (2003). Towards assessment of prosodic abilities in Swedish children with language impairment. Logoped Phoniatr Vocol, 28,
[7]. Shriberg, L., Aram, N., & Kwaitkowski, J. (1997). Developmental apraxia of speech: II. Toward a diagnostic marker. JSLHR, 40, 286–312.