The speech waveform is highly redundant, providing the listener with ensembles of potentially informative acoustic characteristics. Although it can be demonstrated that adults can respond differentially to independently varied acoustic-phonetic cues, it is likely that perceptual learning (Gibson, 1966) during childhood is required in order to achieve this level of speech processing. The voicing distinction in English (e.g. /g/ versus /k/) provides an excellent context for studying developmental changes in the perception of acoustic-phonetic information. It was hypothesized that among the acoustic cues to the prevocalic voicing distinction, voice onset time (VOT) would take priority as an effective cue over fundamental frequency (F0). A speech perception test was administered in which words that varied phonemically in their initial consonant (i.e. gate vs Kate) were presented in a two-alternative forced choice labeling procedure to four- and six-year-old children and adults. The stimuli were synthesized and varied factorially in terms of VOT and F0. Results show that, in contrast with adults, for children even at age six years, F0 is not a factor in judging the voicing of the prevocalic stops /g/ and /k/. Results contribute to growing evidence that speech perception undergoes significant change during childhood.