Effect of stimulus Category. A. Main effect of stimulus category. Vocoder degraded speech (degraded IS and US) vs. vocoder degraded E (IS+US vs. 2E). The horizontal slice is at the coordinate z = -3 (p < 0.0001). IS-Intelligible Speech, US-Unintelligible Speech, ES-Environmental Sounds. In each group, the darker the color in the bar graphs of BOLD signal variation, the higher the level of vocoder degradation. In blue, areas from TVA localizer are presented at p < 0.05, FWE corrected. B. Degradation effect for speech vs. degradation effect for environmental sounds as defined by the expression (Speechdegraded-Speechnormal)-(Soundsdegraded-Soundsnormal). It can be algebraically rewritten as (Soundsnormal-Soundsdegraded)-(Speechnormal-Speechdegraded). The latter formula makes clear that the difference between normal and degraded stimuli in the right STS is smaller for speech compared with non-speech sounds. In each group, the darker the color in the bar graphs of BOLD signal variation, the higher the level of vocoder degradation.
Strelnikov et al. BMC Neuroscience 2011 12:122 doi:10.1186/1471-2202-12-122