Phonological mean length of utterance in specific language impairment: a multi-case study of children acquiring Finnish

How many words make a sample? Determining the minimum number of word tokens needed in connected speech samples for child speech assessment

Connected speech (CS) is an important component of child speech assessment in both clinical practice and research. There is debate in the literature regarding what size sample of CS is required to facilitate reliable measures of speech output. The aim of this study was to identify the minimum number of word tokens required to obtain a reliable measure of CS across a range of measures. Participants were 776 5-year-olds from a longitudinal community population cohort study (Avon Longitudinal Study of Parents and Children, ALSPAC). Children's narratives from a story retell task were audio-recorded and phonetically transcribed. Automatic analysis of the transcribed speech samples was completed using an automated transcription and analysis system. Measures of speech performance extracted included: a range of profiles of percentage consonant correct; frequency of substitutions, omissions, distortions and additions (SODA); percentage of syllable and stress pattern matches; and a measure of whole word complexity (Phonological Mean Length of Utterance, pMLU). Statistical analyses compared these measures at different CS sample sizes in increments using averages and weighted moving averages, and investigated how measures performed between CS samples grouped into word tokens of at least 50, 75 and 100, and restricted to samples of 50-74, 75-99 and 100-125. Key findings showed that sample sizes of 75 word tokens and above showed minimal differences in most measures of speech output, suggesting that the minimum requirement for samples of CS is a word count of 75. The exception to this is in the case of pMLU and measures of substitutions and distortions when a word count of 100 is recommended.

Whole-word measures and the speech production of typically developing Dutch children

In this study, the phonological whole-word measure Phonological Mean Length of Utterance was applied to identify stages in the phonological acquisition of Dutch children. Ninety spontaneous speech samples of 47 typically developing Dutch children from a previous study were examined. Samples were distributed across nine age groups ranging between 1;3-4;0 years. Across all age groups, PMLU of word productions increased significantly with the largest increase found below age 2;0 years. PMLU of the target words showed no significant increase across age groups. Outcomes suggest that the phonological whole-word measure PMLU can be further developed for clinical purposes in Dutch-speaking children. In the future, this measure could become relevant for the diagnosis and evaluation of therapy on the basis of spontaneous language.

Maternal input to children with specific language impairment during shared book reading: is mothers' language in tune with their children's production?

BACKGROUND

The literature on input addressed to children with specific language impairment (SLI) has shown contrasting results on the role that parents assume during conversational interactions. Some studies have shown that parents compensate for the child's linguistic limitations. In contrast, other studies have indicated that mothers are able to adjust their communication in response to their children's language characteristics.

AIMS

To assess the 'closeness of fit' between maternal input and child language profiles in children with SLI during shared book reading. To achieve this aim, the individual linguistic features of a group of children with SLI and their mothers were compared with those of two typically developing (TD) groups and the 'distances' (i.e., the differences between the mother's and her child's linguistic indices) within each dyad were compared.

METHOD & PROCEDURES

Three groups of children with their mothers participated in the study: 14 children with expressive SLI, 14 language age-matched TD children (LA-matched group), and 14 chronological age-matched TD children (CA-matched group). Each mother-child dyad was videotaped during two weekly sessions of shared book reading, at home. All sessions were entirely transcribed. For each session, the following indices were then considered: whole-word phonological indices, grammatical categories and lexical indices for types and tokens, and the distance between the mother's and the child's linguistic indices within individual dyads.

OUTCOMES & RESULTS

Analysis of the differences between phonological, lexical and morphosyntactic characteristics of the mothers' and children's language indicated that both children with SLI and their mothers produced adjectives and adverbs with lower phonological complexity and with higher frequency of use compared with the CA-matched group, and nouns with lower frequency of use and higher age of acquisition compared with the LA-matched group. In addition, individual dyads within the SLI group displayed reduced distances between linguistic indices produced by the mother and child compared with dyads within the CA-matched group.

CONCLUSIONS & IMPLICATIONS

On the whole these findings suggest that mothers of children with SLI are able to tune their language to their children's linguistic limitations. These findings may contribute to improving early intervention programmes with children with SLI by focusing on the mother-child interaction during shared book reading.