Three-Month-Olds Prefer Speech to Other Naturally Occurring Signals

Human infants show a preference for listening to speech, but little is known about how infants listen to other naturally occurring sounds. Here, we test infants’ listening bias for speech against a range of naturally occurring sounds that share properties of speech to varying extents and we aim to better characterize the speech properties that attract infant attention. We compared 3-month-olds’ listening patterns for five types of sounds: nonnative speech, rhesus macaque vocalizations, human noncommunicative vocalizations, human communicative nonspeech vocalizations, and environmental sounds. Across three experiments, 3-month-olds preferred speech to the other four types of sounds. The set of acoustic properties we measured—pitch, peak amplitude, nonzero-root mean square amplitude, frequency difference and amplitude variance—did not predict infant looking time. Our results demonstrate that young infants attend selectively to speech over many other naturally occurring stimuli, an important tool for learning language.