Bang, Kachergis, Weisleder, Marchman
Some
theories of language development propose that children learn more effectively
when exposed to speech that is directed to them (target child directed
speech, tCDS) than when exposed to speech that is directed to others
(other-directed speech, ODS). During naturalistic daylong recordings, it is
useful to identify periods of tCDS and ODS, as well as periods when the child
is awake and able to make use of that speech. To do so, researchers typically
rely on the laborious work of human listeners who consider numerous features
when making judgments. In this paper, we detail our efforts to automate these
pro-cesses. We analyzed over 1,000 hours of audio from daylong recordings of
153 English- and Spanish-speaking families in the U.S. with 17- to 28-month-old
children that had been previously coded by hu-man listeners for periods of
sleep, tCDS, and ODS. We first explored patterns of features that
character-ized periods of sleep, tCDS, and ODS. Then, we evaluated two
classifiers that were trained using auto-mated measures generated from
LENATM, including frequency (AWC, CTC, CVC) and duration (mean-ingful speech,
distant speech, TV, noise, silence) measures. Results revealed high
sensitivity and speci-ficity in our sleep classifier, and moderate sensitivity
and specificity in our tCDS/ODS classifier. Moreo-ver, model-derived
predictions replicated previously-published findings showing significant and
posi-tive links between tCDS, but not ODS, and children’s later vocabularies
(Weisleder & Fernald, 2013). This work offers promising tools for
streamlining work with daylong recordings, facilitating research that aims to
better understand how children learn from everyday speech environments.