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Jasmine F Awad, Woon Ju Park, Ione Fine; Enhanced auditory segregation in early blind individuals. Journal of Vision 2019;19(10):167. doi: https://doi.org/10.1167/19.10.167.
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© ARVO (1962-2015); The Authors (2016-present)
Early loss of vision forces blind individuals to rely on auditory information to track the position and motion of objects in space. Here we examined whether early blindness leads to an enhanced ability to segregate moving and stationary auditory stimuli on the basis of frequency. Methods. Participants were seven EB individuals and three sighed controls (SC; matched by age and musical experience). Auditory segregation abilities were measured using a psychophysical notch paradigm. Stimuli consisted of three simultaneously presented non-overlapping broadband white noise stimuli. The target was a mid-frequency band (851–1691Hz). Masking notch width was manipulated by changing the width of two flanking masking noise bands. For the narrowest notch the low frequency noise band fell between 300Hz–776Hz, and the high frequency noise band fell between 1856–4800Hz. For the widest notch low and high frequency noise bands fell between 300Hz–534Hz and 2694–4800Hz respectively. In the static task subjects had to detect the presence of the target band, and in the motion task subjects had to report its direction of motion. Amplitude threshold was measured at each notch width and the slope of threshold as a function of notch width was used to characterize auditory filter widths. Results. As expected, thresholds decreased as a function of notch width for both sighted and blind participants, across both tasks (ANOVA, group × task × notch width: F(4, 70) = 34.53, p< 0.0001). Slopes were steeper in the static task, suggesting narrower filters for detection than motion direction judgments (F(1, 70) = 11.07, p=0.0014). EB participants showed steeper slopes than SC participants for both tasks, indicating narrower perceptual auditory filters as a result of early blindness F(4, 70) = 34.53, p< 0.0001). These results suggest that early blindness leads to an increased ability to segregate auditory objects based on auditory frequency.
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