Children hear the forest.

How do children develop the ability to recognize phonetic structure in their native language with the accuracy and efficiency of adults? In particular, how do children learn what information in speech signals is relevant to linguistic structure in their native language, and what information is not? These questions are the focus of considerable investigation, including several studies by Catherine Mayo and Alice Turk. In a proposed Letter by Mayo and Turk, the comparative role of the isolated consonant-vowel formant transition in children's and adults' speech perception was questioned. Although Mayo and Turk ultimately decided to withdraw their letter, this note, originally written as a reply to their letter, was retained. It highlights the fact that the isolated formant transition must be viewed as part of a more global aspect of structurein the acoustic speech stream, one that arises from the rather slowly changing adjustments made invocal-tract geometry. Only by maintaining this perspective of acoustic speech structure can we ensure that we design stimuli that provide valid tests of our hypotheses and interpret results in a meaningful way.