The effect of intermittent noise on lexically-guided perceptual learning in native and non-native listening

There is ample evidence that both native and non-native listeners deal with speech variation by quickly tuning into a speaker and adjusting their phonetic categories according to the speaker's ambiguous pronunciation. This process is called lexically-guided perceptual learning. Moreover, the presence of noise in the speech signal has previously been shown to change the word competition process by increasing the number of candidate words competing for recognition and slowing down the recognition process. Given that reliable lexical information should be available quickly to induce lexically-guided perceptual learning and that word recognition is slowed down in the presence of noise, and especially so for non-native listeners, the present study investigated whether noise interferes with lexically-guided perceptual learning in native and non-native listening. Native English and Dutch listeners were exposed to a story in English in clean speech or with stretches of noise. All the /l/ and /ɹ/ sounds in the story were replaced with an ambiguous sound half-way between /l/ and /ɹ/. Although noise altered the pattern of responses for the non-native listeners in a subsequent phonetic categorization task, both native and non-native listeners demonstrated lexically-guided perceptual learning in both clean and noisy listening conditions. We argue that the robustness of perceptual learning in the presence of intermittent noise for both native and non-native listeners is additional evidence for the remarkable flexibility of native and non-native perceptual systems even in adverse listening conditions.