Fig 1.
Audiogram (mean ± 1 SE) of the averages (right and left) of YNH (red line), ONH (black line) and OHI (dashed-gray line) adults. Thin lines represent the PTA of the individual subjects, while thick lines represent the grand average. YNH and ONH have pure-tone averages ≤ 25 dB HL from 125 to 4000 Hz, while OHI have an average hearing loss across 500–4000 Hz of 26 dB HL or worse.
Fig 2.
Grand averages for YNH (n = 17, left column), for ONH (n = 15, middle column) and for OHI (n = 14, right column) of FFRs to the stimulus envelope recorded in quiet (black) vs -6 dB noise (red). Overall results show a stronger response in younger adults in both the transition (18–68 ms) and steady-state (68–170 ms) regions. The presence or absence of hearing loss in older adults does not significantly affect the strength of the response.
Fig 3.
RMS values ± 1 SE for ONH (black) and OHI (Gray) adults in the transition (left) and steady-state (right) regions for all of the noise levels tested. Higher amplitudes were noted in the quiet condition in the YNH vs. either ONH or OHI. A steeper amplitude decline from quiet to noise conditions was noted in YNH compared to ONH or OHI groups. p-values in this figure refer to the results of the post-hoc independent t-tests analysis. *p < 0.05, **p < 0.01.
Fig 4.
Pearson correlation coefficients ± 1 SE of the quiet-to-noise correlation for YNH (red), ONH (black) and OHI (gray) in the transition (left) and steady-state (right) regions for all of the noise levels tested. Significant differences were noted between YNH and OHI but not between YNH and ONH or ONH and OHI. p-values in this figure refer to the results of the post-hoc independent t-tests analysis. *P < 0.05, **p < 0.01, ***p < 0.001.
Fig 5.
Correlation values measured in the MEG experiment.
Left: plots of r values for each YNH (red), ONH (black) and OHI (gray) participant at each condition tested (o = Quiet, * = +3 dB, Δ = 0 dB, Υ = -3 dB, + = -6 dB) plotted in ascending noise order with respect to the quiet condition. Right: Reconstruction accuracy value 1 ± SE of the speech envelope of the foreground for YNH, ONH and OHI in quiet and in noise. The bottom horizontal line shows the noise floor. Older adults’ reconstruction fidelity is significantly better than that of the younger adults at all of the noise levels tested, but at -6 dB in OHI. No significant differences and no interactions were found between ONH and OHI.
Fig 6.
Reconstruction accuracy in quiet and at all the noise conditions tested for the 3 integration windows tested: 500, 350, and 150 ms.
Significant differences across the 3 integration windows were found only in ONH in both quiet and at all the noise conditions tested. The size of the integration window seems to be playing a critical role only in older adults with normal hearing. *p < 0.05, **p < 0.01, ***p < 0.001.
Fig 7.
Unadjusted scale score of the Flanker Inhibitory Control and Attention test for each subject plotted in ascending order.
NHY scored significantly better than ONH and OHI, but no significant differences were found between ONH and OHI. ***p < 0.001.