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Poster E75, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

The importance of cognitive plasticity and speaker’s voice in adaptation to distorted speech stimuli.

Dan Kennedy-Higgins1, Joseph T. Devlin2, Patti Adank1;1Department of Speech, Hearing & Phonetic Sciences, University College London, UK, 2Department of Experimental Psychology, University College London, UK

Everyday communication occurs in the presence of a myriad of distortions that all combine to make speech perception challenging. Whilst speech comprehension is often slower and less efficient in adverse listening conditions, listeners demonstrate significant and rapid plasticity in adaptation to the degraded incoming signal. Results of previous functional imaging studies suggest that individual differences in this rapid adaptation is dependent on the recruitment of higher level language areas beyond the temporal gyrus. Whilst activation in this region is important, the recruitment of the left inferior frontal, ventral premotor and inferior parietal regions is associated with greater levels of adaptation to distorted speech stimuli (Adank & Devlin, 2010; Davis & Johnsrude, 2003) with particular importance placed on the functional links that exist between these regions (Eisner, McGettigan, Faulkner, Rosen, & Scott, 2010). We aimed to investigate how behaviourally robust this system is in three ways, first, by using a within-group design (n=90) to examine how participants adapt to three different types of manipulations, noise-vocoding, time-compression, and speech in noise. Second, we examined the effect of mixed-speaker presentation on adaptation to distorted speech. Third, we investigated if and how individual differences in performance on an array of cognitive tasks links to perceptual adaptation to distorted speech. Following a battery of audiological and cognitive assessments, 90 participants (average age 21.4years +/- 2.74; 65 female) completed a speeded sentence verification task for sentences consisting of a noun plus predicate (e.g. Admirals are people/Admirals have fins). Sentences were blocked by distortion condition, with participants hearing 48 sentences per block (192 overall). Four different types of speech were used: clear (baseline); noise-vocoded (4 channel); time compressed (to 40% of original length) and speech in noise (-4dB SNR), in a counterbalanced order with the clear condition always presented first. Sentences were produced by four male speakers of southern British English. Accuracy and reaction times were used as indicators of adaptation. Participants adapted most to the time-compressed condition, followed by the noise condition with no adaptation occurring in the noise-vocoded condition. The results further showed that adaptation was speaker-specific, with listeners adapting to varying degrees across the four speakers. Lastly, greater overall performance was linked most closely to individual differences in performance on measures of executive functioning (e.g. working memory and vocabulary knowledge). These results suggest that cognitive mechanisms for adapting to distorted speech are affected by the type of distortion, but that the extent to which an individual adapts also depends on the speaker they are listening to as well as their individual cognitive flexibility. References: Adank, P., & Devlin, J. T. (2010). On-line plasticity in spoken sentence comprehension: Adapting to time-compressed speech. NeuroImage, 49(1), 1124-1132. doi: Davis, M. H., & Johnsrude, I. S. (2003). Hierarchical Processing in Spoken Language Comprehension. The Journal of Neuroscience, 23(8), 3423-3431 Eisner, F., McGettigan, C., Faulkner, A., Rosen, S., & Scott, S. K. (2010). Inferior Frontal Gyrus Activation Predicts Individual Differences in Perceptual Learning of Cochlear-Implant Simulations. The Journal of Neuroscience, 30(21), 7179-7186. doi: 10.1523/jneurosci.4040-09.2010

Topic Area: Perception: Speech Perception and Audiovisual Integration

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