The effects of talker variability and variances on incidental learning of lexical tones

Multi-talker variability has been found to be very effective in the perception and production training of nonnative sound categories in the past few decades. The phonetic training paradigms were mostly explicit learning in which learners received feedback of the categories when exposed to the training stimuli. More recently, studies have started to investigate how auditory categories are learned by adults incidentally during unsupervised training—a simulation of sound category learning in a natural environment without any experimenter-provided feedback. The stimuli used in incidental learning were mostly re-synthesized nonspeech sound categories due to the ease of manipulating the variance of different acoustic dimensions. Very few studies examined the effect of talker variability on incidental learning of novel speech categories. This study investigated whether American adults without any tone language experience can learn Mandarin Chinese lexical tones incidentally by playing a video game. We also examined the effects of carefully manipulated variability of the re-synthesized stimuli and the natural variability of multitalkers on lexical tone category learning. In addition to tone discrimination and identification, we also examined the participants’ cue-weighting change after the incidental learning. The result showed that novel speech categories, lexical tones in this case, can be learned incidentally. The results also showed that multi-talker stimuli not only led to better generalization for the identification of tones in stimuli not present in the training but also made learners have a more nativelike cue-weighting in tone perception. The results suggest that the manipulation of variance on significant acoustic dimensions such as pitch direction and height may not be as robust as talker variability in terms of learning lexical tones when incidental learning occurred.