The Decibel Analysis for Research in Teaching (DART; Owens et al., 2017), a sound-based metric of learner-centeredness, is highly accessible, requires no training, and can be conducted with minimal classroom observations; yet, DART has not been evaluated in comparison with other validated metrics or in consideration of potentially confounding classroom characteristics (e.g. enrollment, classroom size, number of doors). We analyzed recordings from 42 class sessions of an undergraduate biology course with DART, the Reformed Teaching Observation Protocol (RTOP), and nine classroom characteristics. We found that enrollment was the best single predictor of the DART output of learner- centeredness, percent Multiple Voice.