The interplay between prior knowledge and semantic coherence during processing of degraded speech: an fMRI study
2015 (English)In: Abstract book: Third International Conference on Cognitive Hearing Science for Communication, 2015, 181-181 p.Conference paper, Poster (Other academic)
Degraded speech is rendered more intelligible both by semantic coherence and preceding text cues. Recently, we showed that the perceptual clarity of noise-vo-coded speech (NVS) is still enhanced by semantic coherence when cues are provided and that prior knowledge enhances perceptual clarity of NVS when semantic coherence is low (Signoret et al., 2015). Here, we investigated the neural correlates of this interaction. Twenty participants listened to sentences and performed an unrelated attentional task during sparse-imaging fMRI. The sentences had high or low semantic coherence, and were either clear, degraded (6-band NV) or unintelligible (1-band NV). Each spoken word was preceded (200 ms) by either a matching cue or a consonant string. Preliminary results revealed significant main effects of both Coherence and Cue in the superior temporal gyrus bilaterally and a significant interaction between Coherence and Cue when speech was degraded, in superior and middle temporal gyri bilaterally and left precentral gyrus. Investigation of this interaction revealed greater activation for high compared to low coherent sentences when cues were provided in the left-lateralized regions and greater activation without than with cues when semantic coherence was low in bilateral regions. The opposite contrasts elicited no significant activation. This pattern of results indicates that the increases in perceptual clarity of NVS attributable to semantic coherence and prior knowledge are supported by similar neural mechanisms organized in bilateral temporal regions, but that when perceptual clarity is optimized by both factors, it is supported by left-lateralized mechanisms.
Place, publisher, year, edition, pages
2015. 181-181 p.
IdentifiersURN: urn:nbn:se:liu:diva-123963OAI: oai:DiVA.org:liu-123963DiVA: diva2:894517
Third International Conference on Cognitive Hearing Science for Communication (CHSCOM2015), Linköping, Sweden, 14–17 June 2015