Speech Segmentation with Prosodic and Statistical Cues Is Language-Specific in Infancy

Speech segmentation is one of the first tasks infants face when learning their mother tongue. It has been argued that statistical learning could function as a gateway to speech segmentation in the absence of pre-existing knowledge about the language to be acquired. However, infants also segment speech with prosodic cues, such as lexical stress. Here, we review recent evidence from studies that look at how infants weigh statistical and prosodic information when segmenting continuous speech. We argue that the idea that statistical regularities have a main role in early speech segmentation, as evidenced in English-learning infants, is not found with German-learning infants. With more natural speech stimuli, German-learning infants only become sensitive to statistical regularities in the speech signal by their first birthday. We provide further support for this hypothesis by showing that there are cross-linguistic differences in how statistical models segment child-directed speech (CDS) and that CDS changes as infants grow. This suggests that speech input to younger infants is not tailored for speech segmentation with statistical cues, but that it is subject to cross-linguistic differences like prosody.