Article Figures & Data
Figures
- Figure 1.
An illustration depicting the generation of the noise-vocoded signal. The input signals were bandpass filtered into 4 (BPF1), 8 (BPF2), 16 (BPH3), and 32 (BPF4) channel bands prior to Hilbert transformation. After separating the envelopes from the temporal fine structures, the vocoder speech signal was generated by adding a noise carrier to the envelopes.
- Figure 2.
Spectrograms for the number of channels (4, 8, 16, and 32) at cutoff frequencies of 50 or 500 Hz. With fewer channel bands and a lower cutoff frequency, the speech becomes more spectrally degraded and difficult to understand.
- Figure 3.
Sample waveforms averaged from the corresponding electrodes for N2 and P3b. For N2, it represents the average values obtained from Fz, FC1, FC2, and Cz channels. For P3b, it represents the average values obtained from CP1, CP2, P3, Pz, and P4 channels.
- Figure 4.
Digit span test. The correct score was higher in the early-blind group than in the sighted group in the forward (p < 0.001) and backward (p = 0.004) conditions.
- Figure 5.
Monosyllable word recognition in noise. The early-blind subjects demonstrated better recognition compared with the sighted subjects in all SNR conditions (all p < 0.01).
- Figure 6.
Sentence recognition in noise. The speech recognition threshold was significantly lower in the early-blind group compared with the sighted group for the SSN test (p = 0.002) and the ISTS noise test (p < 0.001).
- Figure 7.
Vocoded speech recognition under envelope cutoff frequencies of 50 Hz (left panel) and 500 Hz (right panel). The early-blind group showed better recognition compared with the sighted group (p < 0.001). Group showed an interaction with channels (p = 0.007) but not with the envelope cutoff frequency (p = 0.057).
- Figure 8.
N2 latency and amplitude. The early-blind group showed a shorter latency in the 8-channel test (p = 0.022) and the 16-channel test (p = 0.049) and a greater amplitude in the 8-channel test (p = 0.034) compared with the sighted group (Bonferroni-corrected p < 0.05).
- Figure 9.
P3b latency and amplitude. The early-blind group tended to show a greater amplitude in the 8-channel test compared with the sighted group (p = 0.067; Bonferroni-corrected p < 0.05).
Tables
Subject Age (years) Onset Sex Visual acuity Cause of blindness B01 32 Birth F Light perception Retinopathy of prematurity B02 25 Birth M No light perception Optic atrophy B03 28 Birth F Light perception Optic atrophy B04 22 Birth F No light perception Retinopathy of prematurity B05 27 Birth M Light perception Microphthalmos B06 39 Birth M Light perception Optic atrophy B07 32 Birth M No light perception Persistent hyperplastic primary vitreous B08 22 Birth F No light perception Retinopathy of prematurity B09 28 Birth M No light perception Retinopathy of prematurity B10 39 Birth F No light perception Cataract B11 34 Birth F Light perception Retinoblastoma B12 28 Birth M No light perception Retinopathy of prematurity B13 29 Birth F No light perception Retinopathy of prematurity B14 26 Birth M No light perception Corneal opacity B15 30 Birth F No light perception Retinopathy of prematurity B16 34 Birth M Light perception Retinopathy of prematurity B17 35 Birth M Light perception Cause unknown B18 31 Birth M Light perception Cause unknown B19 36 Birth F Light perception Retinopathy of prematurity B20 34 Birth M NO light perception Meningitis B21 37 Birth F NO light perception Optic atrophy B22 25 Birth M NO light perception Cause unknown B23 27 Birth M NO light perception Retinopathy of prematurity B24 32 Birth M Light perception Cause unknown B25 26 Birth M Light perception Xanthochromism Sum of square df Mean square F p SNR 4,695.30 4.00 1,173.83 456.52 <0.001 0.905 Group 300.304 1 300.304 46.511 <0.001 0.492 SNR*Group 19.816 4 4.954 1.927 0.108 0.39 Residual 493.68 192.00 2.57 Sum of square df Mean square F p Channels 11,986.85 3.00 3,995.62 873.45 <0.001 0.905 Envelop 453.690 1.000 453.690 256.051 <0.001 0.842 Group 345.960 1 345.960 20.604 <0.001 0.300 Channels*Group 57.420 3.00 19.140 4.184 0.007 0.080 Channels*Envelop 74.090 3 24.697 16.641 <0.001 0.257 Envelop*Group 6.760 1.000 6.760 3.815 0.057 0.074 En*Ch*Gr 11.700 3 3.900 2.6828 0.053 0.052 Residual (channels) 658.73 144.00 4.57 Residual (envelop) 85.050 48.000 1.772 Residual (channels*envelope) 213.710 144 1.484
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