JCPSLP Vol 23 Issue 2 2021

Implementation science

Retrospective parent report of early vocal behaviours in children with phonological delay Chantelle Highman, Chloe Harper, Neville Hennessey, and Suze Leitão

Children with speech sound disorders comprise a heterogenous group and often form a large part of a speech-language pathologist’s caseload in a paediatric setting. The early vocal development of these children is of interest, both in understanding the nature of various speech difficulties and for informing the possibility of early identification. Limited babbling has been reported and observed in children later diagnosed with childhood apraxia of speech (CAS); however, the early development of children with more common speech sound disorders, such as phonological delay (PD), has not been extensively studied. The present study sought to quantify parent report of the early vocal, language and motor development of children with PD. Questionnaire data indicated that the PD group reported results similar to those of the typically developing group on key vocal, language and motor behaviours in early development. S peech sound disorders (SSDs) represent the most common type of communication disorder on the caseloads of Australian speech-language pathologists (SLP) (McKinnon et al., 2007), consistent with international findings (Brumbaugh & Smit, 2013; Joffe & Pring, 2008). Prevalence figures for children of all ages range from 2% to 25% (Dodd, 2005), and at 3.4% for children aged four (Eadie et al., 2015). These children, however, comprise a heterogeneous group, with a range of difficulties in aspects of speech sound acquisition, processing, and production (McLeod & Baker, 2017). SSDs are broadly classified according to the observed pattern of presentation and associated hypothesised underlying deficits. At the highest level of classification, speech sound disorders of a motor speech nature (i.e., childhood apraxia of speech, dysarthria) are often contrasted with those of a phonological nature (McLeod & Baker, 2017). There is increasing interest in the pre-linguistic period in children with speech and language disorders, that is, the time before first words emerge (Oller et al., 1999). The potential to identify difficulties early, and therefore the potential to provide more timely intervention, contributes

to this interest. Anomalies in pre-linguistic vocalisations have been reported in children with both recognised neurodevelopmental disorders such as autism (e.g., Brisson et al., 2014), as well as idiopathic speech and language delays/disorders (Morgan & Wren, 2018; Oller et al., 1999; Overby et al., 2020). The extent to which indicators of SSDs may be apparent in the early vocalisations and babbling of later diagnosed children, however, is not yet clear. A late onset of canonical babbling has been identified in some children with restricted expressive language at 2 years of age (Eilers et al., 1996; Stoel-Gammon, 1989). Stoel-Gammon (1989), for example, reported on two children with restricted phonological and lexical development at 2 years of age, one of whom had demonstrated late canonical babbling and the other limited consonant variety in their babble. Larger cohort studies have also highlighted the importance of this pre-speech milestone. In a sample of over 3400 infants, Oller and colleagues (1999) reported persistently smaller expressive vocabularies from 18 to 30 months in children who were not babbling by 10 months of age. Using parent-reported communication measures for a sample of over 1700 children, communication development at 12 months of age was a stronger predictor of language ability at 24 months of age than 12 commonly accepted risk factors drawn from the literature (Reilly et al., 2007). More specific research investigating different types of speech and language difficulties has been limited, however. Children with childhood apraxia of speech (CAS) have been described as having been “quiet” infants who do not babble much (Davis & Velleman, 2000). These clinical anecdotes have been supported by both retrospective studies of parent report (Aziz et al., 2010; Highman et al., 2008) and analysis of early home videos (Overby et al., 2020; Overby & Caspari, 2015). The prelinguistic development of children with phonological impairment not suspected to be of motor speech origin, however, has not been extensively researched. In 2008, we published a study quantifying parental report of early vocalisations in children with suspected childhood apraxia of speech (sCAS, n = 20), compared to those with developmental language disorder 1 (DLD, n = 20), and those with speech and language skills that were typically developing (TD; n = 20) (Highman et al., 200). We aimed to quantify and compare reports of early vocal development via a questionnaire completed by parents. Parents provided information about their child’s early babbling and vocalisations, as well as other developmental speech, language, and motor, milestones.

KEYWORDS INFANT VOCALISATIONS PARENTAL REPORT PHONOLOGICAL DELAY SPEECH SOUND DISORDERS THIS ARTICLE HAS BEEN PEER- REVIEWED

Chantelle Highman (top) and Chloe Harper

95

JCPSLP Volume 23, Number 2 2021

www.speechpathologyaustralia.org.au