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Experiments with Frequency Band Filtered Auditory and Visual Speech: A SPIN task and MEG imagining| old_uid | 3149 |
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| title | Experiments with Frequency Band Filtered Auditory and Visual Speech: A SPIN task and MEG imagining |
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| start_date | 2007/09/06 |
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| schedule | 13h30 |
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| online | no |
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| summary | The first study examined used an Auditory Only (AO) and an Auditory-Visual (AV) SPeech In Noise (SPIN) identification task to examine how auditory and visual speech cues interact. Auditory speech was filtered using an approach developed by Zeng et al (2005) [PNAS, 102, 2293-2298] into "AM" stimuli (where the temporal envelope was modulated at the centre frequency of each of four sub-bands and then summed) and AM+FM stimuli which also included the gradual changes around a fixed frequency in the sub-band. The results show an advantage for the AM+FM (compared to AM only); this FM advantage was the same size for both the AO and AV speech conditions. This pattern suggests that the filtered auditory speech used and visual speech provided non-redundant cues for speech identification.
The second study investigated the affect of seeing the talker on auditory evoked fields (N100m) for speech, filtered speech and non-speech stimuli. Neuromagnetic responses to Auditory Only (AO) and (AV) were recorded with a 306-channel whole-scalp neuromagnetometer and a behavioural task (syllable detection) was also used. The behavioural data showed an AV latency and hit-rate advantage for all auditory stimuli. The neuromagnetic data showed N100m reached maximal amplitude to the speech stimuli was smaller to the filtered speech stimuli and considerably smaller to the non-speech stimuli. The N100m amplitude was decreased for both the speech and filtered speech stimuli in AV condition, as compared to AO. This reduction effect was more pronounced in the right than in the left hemisphere. There was no significant N100m reduction for the non-speech stimuli. This pattern is consistent with a functional asymmetry in the temporal processing of speech. |
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| responsibles | Lœvenbruck, Welby |
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