The use of piecewise linear regression to explore development of children's listening-in-noise ability

To explore the development of speech-in-noise comprehension, we tested children 15–48 months in a preferential-looking paradigm; children saw two images and were told which to attend to ( “Find the keys!”). The target voice was masked either by a 9-voice blend (primarily energetic masking) or a single talker (providing informational masking; IM). We used piecewise linear-mixed-effects modeling to identify phases of developmental growth and their corresponding changepoints. Based on 51 participants to date, performance in multitalker babble was best described by a linear model with gradual improvement over time, but the 1-voice-masker condition was well-fit by a combination of three phases: a period of rapid growth until 25.3 months, followed by a period of relative stagnation until 43.4 months, then a second growth period. Bonino et al. (2021) argued that substantial development in IM ability occurs prior to 30 months, which corresponds well with our first phase. The second growth period may represent an increase in the ability to integrate “acoustic glimpses”; prior studies found that 5-year-olds, but not 30-month-olds, can restore interrupted speech, and our elbow at 43 months fits with this timeline. This demonstrates the usefulness of piecewise linear-mixed-effects as an approach to studying development.