Canonical Babbling Development in Infancy: A Systematic Review and Meta-Analysis of Methodological and Ambient Language Influences

Canonical babbling, or the production of adult-like consonant-vowel syllables in infancy,represents a critical milestone in pre-linguistic vocal development and predicts later speech andlanguage outcomes. This systematic review and meta-analysis synthesized findings from 43studies and 1,291 infants aged 5-24 months across 16 language environments to examine howmethodological and contextual factors influence the most common measure of canonical babbling:the canonical babbling ratio (CBR). Results confirmed a robust, linear increase in CBR with age,reinforcing its role as a consistent developmental marker. Different CBR measures yieldedcomparable developmental trajectories. Sampling method significantly affected CBR values, withinteractive free play sessions eliciting higher CBRs than naturalistic home recordings, particularlyin older infants. In contrast, the location of data collection had no effect. Ambient languagecomplexity also shaped CBR: infants acquiring languages with more complex syllable structures(e.g., English, Dutch) initially exhibited lower CBRs compared to infants acquiring languageswith less complex syllable structures (e.g., Mandarin, Spanish). Despite these initial differences,babbling trajectories were predicted to converge by approximately 21 months as infants exposedto languages with more complex syllables demonstrated accelerated CBR growth. Publicationbias was detected, with smaller samples more likely to report inflated CBRs. To address thisissue, simulation-based analyses are reported to estimate sample size recommendations forimproved precision in future research. Together, these results support CBR as a meaningfuldevelopmental marker while offering practical guidance for future research directions andcontinued clinical applications.