JCPSLP Vol 23 Issue 2 2021

(around 5 months). This is in contrast to the sCAS group, for whom 55% were reported by their parents as having not made many sounds. Parents of the children with delayed phonology were significantly more likely to report that their child had babbled as an infant (100%), compared with children with sCAS, and in keeping with report of the DLD and TD groups who were also all reported to have babbled. The PD group were also more likely to have been reported to have produced variegated babble compared to the sCAS group. Parents of children with delayed phonology were more likely to have reported their child as babbling more than or the same as other children (as with the TD group), compared to both other clinical groups. The prelinguistic vocalisation results suggest differences in the early developmental profile of infants later diagnosed with different speech sound disorders. Children presenting with delayed phonological development as preschoolers were not recalled to have had obvious differences in vocalisations and babbling in infancy, in contrast to the children with sCAS whose parents reported anomalies in the prelinguistic period. Given babbling is considered one of the infant’s earliest displays of speech motor control, it may be particularly sensitive to disorders with an underlying speech motor control deficit (Maassen, 2002). Developmental milestones The PD children were reported to have sat upright earlier than the other clinical groups, similar to the TD children (5–6 months) and within developmental expectations. Reported age of smiling and reported age of first steps were similar for all groups in this study. These observations suggest the PD children did not display overt delays in developmental milestones in infancy. Language milestones The emergence of first words and two-word combinations for children with delayed phonology was found to be reported as similar to that of the TD group (9–10 months), and within developmental expectations. In contrast, the sCAS and DLD groups were later in their reported age of emergence of first words, and the sCAS group was significantly later in their reported emergence of two words (at nearly 3 years of age). These results are consistent with theoretical accounts of phonological impairment, where delays in phonology can occur without concomitant language difficulties (McLeod & Baker, 2017). Feeding and dribbling Reported rates of feeding issues for children with PD were similar to those in the TD group and less than for the other clinical groups. Dribbling issues were reported less frequently for the PD children than the sCAS children, consistent with some clinical observations (Davis & Velleman, 2000). Limitations This study relied on the recall ability of the parents involved, and/or their ability to access child health records and notes relevant to the items under investigation. Parents have been shown to be reliable at identifying canonical babbling at the time of its occurrence (Ambroseet al., 2016; Oller et al., 2001). The reliability of retrospective report, however, has not been established, and many factors may impact on this ability (i.e., birth order/position in family, number of siblings). However, the large majority of parents in the present study did not use the unsure option and reported using aids to

p = .036. Matching the TD group, fewer children with PD (3/20 or 15%) were reported to have feeding difficulties than the sCAS and DLD children (9/20 or 45%, for both groups). Dribbling The PD group was significantly less likely to have reported dribbling problems (2/20 or 10%) than the sCAS group (9/20 or 45%), FET p = .015, but there was no difference in comparison to the DLD (4/20 or 20%), FET p = .331, or TD groups (2/20 or 10%). Table 2. Mean (and standard deviation) for parental reported age of emergence (months) of each key measure for the sCAS, PD, DLD and TD groups

Groups

sCAS

PD

DLD

TD

Key measures

M (SD)

M (SD)

M (SD)

M (SD)

Vowel noises

8.2 (3.4)

5.6 (2.7)

8.2 (3.4)

4.9 (2.4)

Reduplicated babbling Variegated babbling

11.0 (2.0)

7.8 (2.0)

10.1 (3.1)

7.2 (1.9)

–

10.2 (2.5)

12.2 (3.5)

9.2 (1.8)

Sat upright

7.4 (2.6)

6.0 (1.1)

7.2 (1.7)

5.6 (1.8)

Smiled

8.6 (3.6)

7.8 (3.3)

16.8 (22.5)

6.9 (3.6)

Crawling

9.1 (2.4)

8.0 (1.8)

9.1 (1.9)

7.5 (1.6)

First steps

13.6 (3.0)

12.3 (2.3)

12.5 (3.2)

11.7 (1.7)

First words

14.0 (6.7)

10.1 (2.5)

13.0 (4.75)

9.2 (2.5)

Two-word combination

33.3 (7.1)

17.21 (4.7)

27.0 (10.4)

14.6 (4.1)

Note. Data for sCAS, DLD and TD comparison groups reproduced from Highman et al. (2008).

Discussion This study sought to quantify the parental report of early vocalisation behaviours in children with phonological delay, compared to those with sCAS, DLD and typically developing speech and language. On most items, parents in the PD group reported their child in a similar way to the group with typical speech and language development. This was in contrast to our previously reported results for children with sCAS (Highman et al., 2008), who were reported to be significantly less vocal, less likely to babble, later in the emergence of first words, and later in the emergence of two word combinations than the typically developing children, as well as specifically less likely to have babbled and later in two-word emergence than the comparison clinical group (DLD). We now reflect on each aspect in turn. Vocalisations and babbling Children with PD were reported by their parents as having vocalised and made sounds as an infant, like the TD group, but in contrast to the sCAS and DLD groups. Of note, all children in the PD group were reported as having “made many sounds” as an infant. They were also reported to have engaged in “cooing” at a similar age to TD infants

98

JCPSLP Volume 23, Number 2 2021

Journal of Clinical Practice in Speech-Language Pathology