Recalibration of auditory phonemes by lipread speech is ear-specific

Listeners quickly learn to label an ambiguous speech sound if there is lipread information that tells what the sound should be (i.e., phonetic recalibration Bertelson, Vroomen, & de Gelder (2003)). We report the counter-intuitive result that the same ambiguous sound can be simultaneously adapted to two opposing phonemic interpretations if presented in the left and right ear. This is strong evidence against the notion that phonetic recalibration involves an adjustment of abstract phoneme boundaries. It rather supports the idea that phonetic recalibration is closely tied to the sensory specifics of the learning context.