Optimizing Auditory Input for Foreign Language Learners Through A Verbotonal-Based Dichotic Listening Approach

Abstract The quality of the physical language signals to which learners are exposed and which result in neurobiological activity leading to perception should be prioritized as it constitutes a variable that is rarely, if ever, considered in language learning. The current study identifies an optimal audio language input signal for Chinese EFL/ESL learners generated by modifying the physical features of language-bearing audio signals. This is achieved by applying the principles of verbotonalism in a dichotic listening context. Low-pass filtered (320 Hz cut-off) and unfiltered speech signals in four different configurations were selectively directed to each hemisphere of the brain through the contralateral ear. The four types of auditory stimuli were: low-pass filtered stimuli in both ears (FL-FR), filtered stimuli in the left ear and unfiltered stimuli in the right ear (FL-R), unfiltered stimuli in the left ear and filtered in the right ear (L-FR), and unfiltered stimuli in both ears (NL-NR). Temporal and spatial neural signatures for the processing of the signals were detected in a combined Event-Related Potential (ERP) and functional Magnetic Resonance Imaging (fMRI) experiment. Results showed that the FL-R configuration provided optimal auditory language input by actively exploiting left-hemispheric dominance for language processing and right-hemispheric dominance for melodic processing, i.e., each hemisphere was fed the signals that it should be best equipped to process and it actually did so effectively. In addition, the L-FR configuration was identified as entirely non-optimal for language learners. Other outcomes included significant load reduction through exposure to FL-FR signals as well as the confirmation that non-language signals were recognized by the brain and did not trigger any language processing. These various outcomes will necessarily entail further research.