Analysis of reaction time at bDLF.

Before the auditory rehabilitation of each subject began, a local enhancement of frequency discrimination could be observed around the hearing-loss cut-off frequency. This local improvement was named bDLF and was also studied at three months post-rehabilitation (Figure 3).

Figure 3: Alteration in DLF in each subject. bDLF is located in the vicinity of the cut-off frequency of the hearing loss.
Figure 3: Alteration in DLF in each subject. bDLF is located in the vicinity of the cut-off frequency of the hearing loss.

Four DLF frequencies are represented: the reference frequency fref, bDLF-1/8 octave, bDLF, and fbDLF +1/8 octave. DLF performance at bDLF decreased in subjects F.P., D.P., A.D. and C.V. three months after the auditory rehabilitation and was unchanged in subject Y.M.. DLFs are plotted on a log scale as a percentage of the frequency tested. Bottom right: alteration in DLF for the control subject S.G.

A two-way repeated-measures ANOVA on RT before and three months after rehabilitation was performed at frequencies surrounding bDLF (bDLF, bDLF-1/8 octave, bDLF and bDL+1/8 octave). No differences in RT were observed with frequency (F3,7971)=1.053, p=0.37). However, RTs were significantly shorter after the auditory rehabilitation (F(1,7971)=28.606, p<10-4) (Figure 4). No significant interaction between the frequencies and the auditory rehabilitation was found (F(1,7971)=0.197, p=0.90).

Figure 4: Mean RT recorded around bDLF (bDLF-1/8; bDLF; bDLF+1/8) before and three months after auditory rehabilitation for the 5 subjects with a hearing aid.
Figure 4: Mean RT recorded around bDLF (bDLF-1/8; bDLF; bDLF+1/8) before and three months after auditory rehabilitation for the 5 subjects with a hearing aid.

fref is the reference frequency and was located one octave before Fc. Around bDLF, reaction times were significantly shorter at 3 months post-rehabilitation. Error bars represent standard errors.

In each subject, a two-factor ANOVA (rehabilitation and frequency relative to bDLF) was performed. Significant differences in RT before and after rehabilitation were found in each subject (subject F.P.: F(1.1543)=16.99, p<10-4; subject D.P.: F(1,1603)=12.17, p<10-3; subject Y.M.: F(1,1547)=59.2, p<10-4; subject A.D.: F(1,1638)=32.39, p<10-4; subject C.V.: F(1,1619)=49.40, p<10-4). In subjects D.P. and A.D., RTs were longer at 3 months post-rehabilitation, whereas they were shorter in subjects F.P., Y.M. and C.V.. In the control subject S.G., RT was significantly shorter at three months post-rehabilitation (F(1,1599)=17.01, p<10-4). No frequency effect or interaction was found (Figure 2).