Barbara Höhle

ABSTRACT Infants and adults use statistical information from the speech input to form phonetic categories. This ability has been shown by numerous experiments presenting the participants with either a bimodal or a unimodal distribution of sounds from an acoustic continuum. However, this ability seems to decrease across the first year of life in parallel with infants’ establishment of the native language phonetic categories.

1 INTRODUCTION Speech to infants—like speech to adults—unfolds as a continuous sequence of sounds in which word boundaries are not marked by a set of unique phonetic cues. Consequently, a crucial aspect of acquiring language involves breaking down this fluent speech stream into meaningful units that align with the words of the language.

One of the major challenges young infants face when learning their native language(s) is to find out which acoustic properties of speech are relevant in the phonological system of the language they hear and which are not. Two main approaches on how children may solve this problem have been put forth: one emphasizes the role of the emerging lexicon in the establishment of phonological categories and the other emphasizes the role of phonetic properties in the speech input.