LENA recordings for the first wave were completed between the August 1, 2017 and July 31, 2018 and recordings for the second wave were completed between February 1, 2018 and January 31, 2019. Each participant family undertook a LENA recording day within two months after turning 6 months and 12 months. Parents rarely used their ability to pause or stop the recording early, with 98.23% of families completing a full 16-hour recording day during the first wave and 97.55% of families during the second wave. Of the ten families that stopped the recording across both waves, six completed at least 10 hours of recording and noted the recording was stopped as the child went to sleep, therefore was included in the total sample. Three families in the first wave and one family in the second wave completed less than 10 hours of recording due to either device malfunction or choosing to stop the recording early and were excluded from further analysis.
The final analysis sample involved 227 families, with 164 in the high education group and 63 in the low education group for the first wave, and 245 families, with 166 in the high education group and 79 in the low education group for the second wave (See Table 1). Note recruitment continued between wave 1 and 2, consequently the larger sample in wave 2. For the first wave, children were aged between 5 and 8 months of age (mean = 5.81) and 53.3% were female. Mother’s average age at birth was 31.34, with 87.7% working until their pregnancy and 56.4% of children being first-born infants. In the second wave children were aged between 11 and 14 months (mean = 11.99) with the same percentage of females.
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As shown in Table 2 there was very little difference between the average number of adult words spoken, child vocalizations and conversational turns for the low and high education groups, at either wave. The only difference of note is at the first wave (6 months), with children in the low education group vocalizing slightly more than those in the high education group. This difference was not apparent in the second wave (12 months). The means from the adult word counts showed families in the high education group talk slightly more to their child than those in the low education group, with this difference growing at the second wave, but the differences are extremely small.
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The plots in Figure 2 – 4 depict the spread of the data demonstrating enormous variation within the two education groups across both waves. As an example, at the first wave the minimum AWC for the low educated group was 2,958 words per day and the maximum count was 37,397 words (mean = 16,747.75; SD = 7,228.62). The minimum AWC for the high educated group was 3,795 words and the maximum were 39,583 words per day (mean = 16,883.58; SD = 7,075.57). This highlights there is little difference between education groups but high variability within education groups and this is consistent for all three LENA measures, revealing high and low adult and child talkers within both education groups.
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Figure 2: Adult word count at 6 and 12 month wave of data collection by maternal education
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Figure 3: Child vocalization count at 6 and 12 month wave of data collection by maternal education
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Figure 4: Conversational turn count at 6 and 12 month wave of data collection by maternal education