The perception of non-native phonological categories in adult-directed and infant-directed speech: An experimental study

In the present study, we test whether adult listeners detect phonological contrasts faster and more accurately in non-native infant-directed speech (IDS) than in non-native adult-directed speech (ADS). 21 participants listened to pairs of speech signals and their task was to decide as quickly as possible whether the signals constitute the same or different words. Each pair of signals contained target vowels or consonants representing a certain category of contrast that was phonologically relevant in a given language but not in Polish, i.e., the native language of the participants of the listening test. The signals were presented in a random order, and each pair occurred in the material twice. Although we demonstrated significant acoustic-phonetic differences between the utterances realized in the IDS and ADS speaking styles, the listeners in our study were not significantly more accurate or faster in the identification of contrasts in either IDS or ADS stimuli.