Investigating common properties of across-channel processing in space, time and speech perception

[B] Brain mechanisms of across-channel processing

We conduct ABR and MEG measurements to monitor brain activities at different stages of auditory processing during exposure to between-frequency/between-ear silent gaps and voiced/voiceless consonants to identify neurophysiological correlates of across-channel processing. Our previous study (Nakano et al., 2008) suggests the inferior colliculus as a possible site for human across-channel processing although further studies are required. MEG can provide a mapping of surface cortical activities in response to subtle differences between voiced and voiceless consonants which occur on the order of 10 msec. ABR provides responses from the brainstem and are analyzed by the method proposed by Willy Wong (Dajani et al., 2005) which allows the reconstruction of speech from the ABR signal. This approach provides one way by which the sounds “heard” by the inferior colliculus can be used to explore the role of IC in across-channel processing.