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www.speechpathologyaustralia.org.au
JCPSLP
Volume 17, Number 3 2015
147
The audio file was transcribed into a Word document
and analysed using the following codes: a successful
child initiation, successful caregiver initiation, connected
utterance, failed utterance, behavioural directive, or
caregiver expansion. The ratio of successful child to
caregiver initiations was also calculated. These measures
were selected as their presence, or absence, provides
an indication of how supportive the HLE is of language
acquisition. See the Appendix for the definitions adhered to
for these codes. An inter-rater reliability analysis using the
Kappa statistic was performed. A total of 297 utterances
from six participants’ recordings were independently
coded for comparison, and there was an almost perfect
agreement,
k
= .949 (95% CI, .919 to .978,
p
< .005).
Results
The first aim of this study was to compare the quality of the
HLE between the two groups. The non-parametric Mann
Whitney
U
test was selected due to the small sample size in
each group (
N
= 5). This test is robust against violations to
normality and is not affected by outliers in the data, and is
therefore a suitable choice for this study. A
p
value of <.05
indicated a statistically significant difference between the
groups. It was hypothesised that the HLE of the children
who were D/HH would be less supportive of language
development. This hypothesis was strongly supported (see
Table 3). Five out of seven measures returned a significant
result, with all but one generating a large effect.
The second aim was to examine whether the quantity of
language exposure was different between the groups. The
hypothesised difference in adult word count, conversational
turn count, and child vocalisation count was not supported.
Adult word count in the D/HH group (
Mdn
= 10335, Range
= 4824–19401) was not significantly different to the NH
group (
Mdn
= 7261, Range = 2617–11857),
U
= 10.0,
p
=
.690,
r
= .17. There was a non-significant difference in the
conversational turn count of the D/HH group (
Mdn
= 293,
Range = 134–659) and the NH group (
Mdn
= 409, Range =
247–666),
U
= 12.0,
p
= 1.000,
r
= .03. The child vocalisation
count was also not significantly different in the D/HH (
Mdn
= 1367, Range = 319–2567) and NH (
Mdn
= 1334, Range
= 887-3292) groups,
U
= 12.0,
p
= 1.000,
r
= .03.
Discussion
The aim of this study was to investigate differences in the
quality and quantity of interaction in the HLE between
children who are D/HH and their caregivers, and children
Table 2. Description of intervention received by
D/HH children
Child
Intervention
HI Female 1 Weekly sessions at Telethon Speech and Hearing
since 4/5 months of age.
HI Female 2 Weekly sessions at Telethon Speech and Hearing
since 3 months of age. Articulation therapy from 3
years.
HI Male 3 Twice weekly sessions at Telethon Speech and
Hearing since birth.
HI Male 4 Weekly sessions at Telethon Speech and Hearing
since 3 months of age. Recently changed to
fortnightly sessions.
HI Female 5 Nature of therapy received at Telethon Speech and
Hearing not provided.
Table 3. Descriptive measures, significance, and effect size for quality of interaction measures
Measure
D/HH (
N
= 5)
Median (range)
NH (
N
= 5)
Median (range)
Significance Effect size (
r
)
Number of successful child initiations
17 (13–24)
32 (22–50)
.008**
.76
a
Number of successful caregiver initiations
16 (12–20)
22 (20–28)
.004**
.80
a
Number of connected utterances
44 (27–144)
196 (85–220)
.016*
.69
a
Number of failed utterances
30 (22–42)
22 (13–30)
.075
.50
a
Number of behavioural directives
17 (10–36)
9 (8–28)
.048*
.56
a
Number of caregiver expansions
5 (1–11)
18 (6–31)
.048*
.56
a
Ratio of successful child to caregiver initiations
1.26 (0.75–1.43)
1.28 (1.05–2.45)
.211
.30
b
Note.
All significance levels were one-tailed.
a
large effect
b
medium effect *
p
< .05; **
p
< .01.
Procedure
The Language Environment Analysis (LENA) system is an
audio-recording device used to collect and analyse verbal
information about the HLE (Aragon & Yoshinaga-Itano,
2012). As part of the therapy program at Telethon Speech
and Hearing, caregivers were provided with feedback
surrounding the HLE using the LENA system. The audio
recordings for this group were therefore pre-existing. The
children wore the device continuously for up to 16 hours,
and the caregivers were instructed on the use of the device,
including communicating and interacting naturally. The
caregivers rated how typical the day was on a 5-point Likert
scale in terms of communication, events that occurred, and
overall behaviour. No days were scored at 2 or below.
The audio recordings for both groups were input into
the LENA system, which automatically generated data
for adult word count, conversational turn count, and child
vocalisation count. Two participants did not record for the
entire day, and consequently did not provide a complete
recording. As such, measures were calculated from a
5-hour period (from 9am to 2pm) for all participants to
ensure consistency. The LENA system calculated data
for each of the five hours, and the hour with the median
number of conversational turns was identified. This hour
was coded to provide the conversational quality measures,
thus ensuring a representative sample of the language
environment.