The home environment and its relation to vocalizations in the first year of life

Prior data has shown that the home environment impacts child development; however, there remains a paucity of research on how the home environment relates to child and adult words. Therefore, the aim of this prospective and quantitative study was to examine the relationship between the home environment and the quantity of vocalizations or words, and conversational turns produced by infants and parents at 3 and 12 months of age.

Seventy-two (56% male) full-term infants were assessed at 3 and 12 months of age. The home environment was assessed in person via interview and observation of the child's home using the Infant-Toddler Home Observation for Measurement of the Environment (IT-HOME) Inventory subscales. Vocalizations were measured using the Language Environment Analysis (LENA) device, which measures the adult word count, child vocalization count and conversational turn count. These measures were then averaged for the most voluble, or vocal hour, in the recording period.

At 3 months, IT-HOME Learning Materials scores were significantly associated with a decrease in adult words. We found a statistically significant difference in LENA outcomes between 3 and 12 months when stratified by sex. Specifically, male infants had significantly fewer vocalizations at 12 months when compared to 3 months, whereas females had more vocalizations. There was also a statistically significant difference in IT-HOME Learning Materials, Organization, Responsivity, and Total scores when comparing 3- and 12-month time points.

These findings reveal that the home environment changes significantly over the first year of life. At 3 months, Learning Materials in the home were related to adult words, while between 3 and 12 months, several aspects of the home significantly changed. Male children had reduced vocalizations between 3 and 12 months; whereas, female children had increased vocalizations during the same time points. Future research should focus on examining these outcomes with multiple measures, time points, and patient populations.