Language use in everyday life can be studied using lightweight, wearable recorders that collect long-form recordings—that is, audio (including speech) over whole days. The hardware and software underlying this technique are increasingly accessible and inexpensive, and these data are revolutionizing the language acquisition field. We first place this technique into the broader context of the current ways of studying both the input being received by children and children's own language production, laying out the main advantages and drawbacks of long-form recordings. We then go on to argue that a unique advantage of long-form recordings is that they can fuel realistic models of early language acquisition that use speech to represent children's input and/or to establish production benchmarks. To enable the field to make the most of this unique empirical and conceptual contribution, we outline what this reverse engineering approach from long-form recordings entails, why it is useful, and how to evaluate success. Expected final online publication date for the Annual Review of Linguistics, Volume 8 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Language use in everyday life can be studied using light-weight, wearable recorders that collect long-form recordings, i.e. audio (including speech) over whole days. We first place this technique into the broader context of the current ways of studying both the input being received by children as well as children’s own language production, laying out the main advantages and drawbacks of long-form recordings. We then go on to argue that a unique advantage of long-form recordings is that they can fuel realistic models of early language acquisition that use speech for representing children’s input and/or for establishing production benchmarks. To enable the field to make the most of this unique empirical and conceptual contribution, we outline what this reverse-engineering approach from long-form recordings entails, why it is useful, and howto evaluate success.

Data availability statement:The data and code necessary to reproduce the analyses presented here are publicly accessible from https://osf.io/t8r5j/ Acknowledgments: HC thanks The Vanuatu Cultural Centers in Port Vila and Malakula, especially directors Marcellin Ambong, Richard Shing, and Numa Fred Longga for their support.