This study is a validation of the LENA system for the Italian language. In Study 1, to test LENA’s accuracy, seventy-two 10-minute samples extracted from daylong LENA recordings were manually transcribed for 12 children longitudinally observed at 1;0 and 2;0. We found strong correlations between LENA and human estimates in the number of Adult Word Count (AWC) and Child Vocalisations Count (CVC) and a weak correlation between LENA and human estimates in Conversational Turns Count (CTC). In Study 2, to test the concurrent validity, direct and indirect language measures were considered on a sample of 54 recordings (19 children). Correlational analyses showed that LENA’s CVC and CTC were significantly related to the children’s vocal production, a parent report measure of prelexical vocalizations and the vocal reactivity scores. These results confirm that the automatic analyses performed by the LENA device are reliable and powerful for studying language development in Italian-speaking infants.

The validity of the Language ENvironment Analysis (LENA) System was evaluated for Dutch. 216 5-min samples (six samples per age per child) were selected from daylong recordings at 5, 10 and 14 months of age of native Dutch-speaking younger siblings of children with autism spectrum disorder (N = 6) and of typically developing children (N = 6). Two native Dutch-speaking coders counted the amount of adult words (AWC), child vocalisations (CVC) and conversational turns (CT). Consequently, correlations between LENA and human estimates were explored. Correlations were high for AWC at all ages (r = .73 to .81). Regarding CVC, estimates were moderately correlated at 5 months (r = .57) but the correlation decreased at 10 (r = .37) and 14 months (r = .14). Correlations for CT were low at all ages (r = .19 to .28). Lastly, correlations were not influenced by the risk status of the children.