JCPSLP Vol 17 No 3 2015

Ambrose, VanDam and Moeller (2011), toddlers who are D/ HH are exposed to approximately 1400 adult words per hour. In a separate study, Hart and Riseley (1995) reported that children who are NH from professional and working- class families heard on average 1702 adult words per hour. Contradicting this apparent discrepancy in the number of words heard, VanDam et al. (2012) found that the D/HH group ( N = 22) and the NH group ( N = 8) were exposed to approximately the same number of adult words, and the children who are D/HH did not participate less in conversational turns. The resulting weaker expressive and receptive language skills were attributed to the quality of the conversational turns, in conjunction with the impact of the hearing loss (Ambrose et al., 2011). This recent study contradicts previous research noting disparities between the populations (Lederberg & Mobley, 1990), causing the language quantity in the HLE to be difficult to predict. Aims The current study had two aims: first, to compare the quality of the HLE of children with and without hearing loss; and second, to consider differences in quantitative language measures recorded in the HLE, namely adult word count, conversational turn count, and child vocalisation count. It should be noted that previous studies had not yielded conclusive findings, and there were often small sample sizes and lack of detail regarding the measures. With regards to parent and child responsiveness, it was hypothesised that the D/HH child–caregiver dyad would demonstrate less successful child and caregiver initiations, fewer connected utterances, and more failed utterances. Similarly, more behavioural directives and a decreased ratio of successful child to caregiver initiations were expected, indicating higher parental conversational control. Fewer caregiver expansions were also expected, signifying a less supportive linguistic environment.

The measures of adult word count (number of adult words spoken near the child), conversational turn count (verbal exchanges between an adult and the child occurring within five seconds of each other), and child vocalisation count (vocalisations at least 50 milliseconds in duration and surrounded by 300 milliseconds of silence) were hypothesised to differ between the groups. This hypothesis was non- directional due to the limited and inconsistent findings from

the literature. Method Participants

Five children who were D/HH and their caregivers were recruited from Telethon Speech and Hearing, a facility that provides early intervention and specialist services for children with speech, language, and hearing difficulties in Western Australia. The children were fitted with a hearing aid or cochlear implant. Five NH children and their caregivers were recruited via the researchers’ informal networks. The NH children were matched by hearing age (plus or minus three months) and gender. Participant matching by maternal education level (e.g., undergraduate degree, trade qualification) was also attempted. See Table 1 for participant characteristics, and Table 2 for the nature of intervention received by the D/HH children. All participants’ primary language at home was English. The NH children passed an audiological screening at 25dB across the frequencies of 500, 1000, 2000, and 4000 Hz in a quiet room. Their language was deemed typically developing (falling within one standard deviation of the mean) using a 52-question caregiver survey, the LENA Developmental Snapshot, or three subtests of the Clinical Evaluation of Language Fundamentals – Preschool (2nd ed.) if over 36 months of age. The LENA Developmental Snapshot permitted time constraints to be adhered to, whilst providing results highly correlated with other standardised language assessments (see Gilkerson & Richards, 2008).

Table 1. Participant characteristics of D/HH and NH children

Chronological age months; days

Hearing age Hearing aid (HA) / Cochlear implant (CI)

Mother’s education level

Diagnoses

HI Female 1 38m; 14d

36m; 7d

HA from 2m; 7d, CI from 35m; 24d

Post graduate degree None

NH Female 1 33m; 7d

–

–

Bachelor degree

None

HI Female 2 51m; 3d

48m; 29d

HA (bilateral) from 2m; 5d

Post-graduate degree

Possible oral motor weakness affecting upper lip and lifting of tongue Mild stutter (<2% syllables stuttered)

NH Female 2 47m; 27d

–

–

Bachelor degree

HI Male 3

42m; 1d

26m; 20d

CI from 14m; 11d

Diploma of education None

NH Male 3 28m, 4d

–

–

Bachelor degree

None

HI Male 4

35m; 1d

34m; 4d

HA from 27d

Senior secondary education (Year 12)

Treacher Collins Syndrome

NH Male 4 33m; 3d

–

–

Trade qualification

None

Did not provide

None

HI Female 5 39m; 10d

31m

HA at approximately 8m; CI (right) at 18m; 26d and (left) at 43m

NH Female 5 29m; 28d

–

–

Post-graduate degree

None

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JCPSLP Volume 17, Number 3 2015

Journal of Clinical Practice in Speech-Language Pathology