What are the sources of variation in the input, and how much do they matter for language acquisition? This study examines frequency variation in manner-of-articulation classes in child and adult input. The null hypothesis is that segmental frequency distributions of language varieties are unigram (modelable by stationary, ergodic processes), and…

Type/Token Ratios (TTRs) frequently fail to discriminate between children at widely different stages of language development, and may fall as children get older. Such effects are caused by a negative, though non-linear, relationship between sample size and TTR. Standardization of the number of tokens before computing TTRs is recommended.…