1 School of Communication Sciences & Disorders, McGill University, Montréal, Quebec, Canada.
2 Centre for Research in Brain, Language and Music, Montréal, Quebec, Canada.
3 Department of Psychology, Concordia University, Montréal, Quebec, Canada.
4 Centre for Research in Human Development, Montréal, Quebec, Canada.

Purpose This study examined the utility of the Language ENvironment Analysis (LENA) recording system for investigating the language input to bilingual infants. Method Twenty-one French-English bilingual families with a 10-month-old infant participated in this study. Using the LENA recording system, each family contributed 3 full days of recordings within a 1-month period. A portion of these recordings (945 minutes) were manually transcribed, and the word counts from these transcriptions were compared against the LENA-generated adult word counts. Results Data analyses reveal that the LENA algorithms were reliable in counting words in both Canadian English and Canadian French, even when both languages are present in the same recording. While the LENA system tended to underestimate the amount of speech in the recordings, there was a strong correlation between the LENA-generated and human-transcribed adult word counts for each language. Importantly, this relationship holds when accounting for different-gendered and different-accented speech. Conclusions The LENA recording system is a reliable tool for estimating word counts, even for bilingual input. Special considerations and limitations for using the LENA recording system in a bilingual population are discussed. These results open up possibilities for investigating caregiver talk to bilingual infants in more detail.