Infant preference for specific phonetic cue relations in the contrast between voiced and voiceless stops.

Acoustic variability in the speech input has been shown, in certain contexts, to be beneficial during infants' acquisition of sound contrasts. One approach attributes this result to the potential of variability to make the stability of individual cues visible. Another approach suggests that, instead of highlighting individual cues, variability uncovers stable relations between cues that signal a sound contrast. Here, we investigate the relation between Voice Onset Time and the onset of F1 formant frequency, two cues that subserve the voicing contrast in German. First, we verified that German-speaking adults' use of VOT to categorize voiced and voiceless stops is dependent on the value of the F1 onset frequency, in the specific form of a so-called trading relation. Next, we tested whether 6-month-old German learning infants exhibit differential sensitivity to stimulus continua in which the cues varied to an equal extent, but either adhered to the trading relation established in the adult experiment or adhered to a reversed relation. Our results present evidence that infants prefer listening to speech in which phonetic cues conform to certain cue trading relations over cue relations that are reversed.