Correlation between spectral modulation depth and correct detection of modulation phase reversal.

<p>Correlations are plotted as a function of carrier band frequency, with results shown separately for each of the five spectral modulation rates. Symbols and lines indicate the correlation values based on 500 trials from each of four listeners. Shaded regions indicate the 95% confidence intervals around those estimates.</p

Thresholds as a function of spectral modulation rate.

<p>Thresholds for spectral modulation phase reversal in dB are plotted as a function of spectral modulation rate. Thin grey lines show thresholds for individual naïve listeners, and the thick black line shows the mean across naïve listeners. Circles show results from five highly practiced listeners (also shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195686#pone.0195686.g003" target="_blank">Fig 3</a>).</p

Thresholds for one- and two-band targets as a function of band center frequency.

<p>Thresholds are plotted as a function of band center frequency for targets spanning two octave-wide bands (left) or one octave-wide band (right). Filled symbols indicate thresholds obtained in the presence of unmodulated noise in the non-target bands (masked condition), and open symbols indicate that target bands were presented without flanking maskers (quiet condition). Each panel shows results for a different modulation rate, as indicated at the top of the panel. Error bars show one standard deviation, computed in log units.</p

Thresholds as a function of spectral modulation rate for two tasks.

<p>Thresholds in dB are plotted for detecting spectral modulation and spectral modulation phase reversal. Error bars show one standard deviation, computed in log units.</p

Examples of idealized magnitude spectra for 0.5 and 2 rpo.

<p>In both cases the nominal spectral modulation depth is 10 dB. The top and bottom rows show standard and target stimuli, respectively. The +/- 6-dB interval rove is not depicted in this figure.</p

Masking release relative to unmodulated noise.

<p>Mean masking release is plotted for modulated noise conditions relative to the unmodulated condition for hearing-impaired (HI; left panel) normal controls with stimulus presentation at either the same intensity (NH; middle panel) or same sensation level (NH_SL; right panel). The difference in mean thresholds relative to the Unmod-M condition at 2, 4, 8, and 16 bands are plotted for the monaural asynchronous condition (Async-M; circles), the dichotic asynchronous condition (Async-D; triangles), the better of the dichotic control conditions (Control-D; bowties), and the mean of the synchronous conditions (Sync-M; dashed line). Error bars indicate standard error of the mean (n = 9 for HI group; n = 7 for NH group; n = 8 for NH_SL group). The shaded region at the bottom of each panel indicates the range over which masking release might be accounted for by reductions in masker level associated with amplitude modulation (3.2 dB).</p

Mean speech recognition thresholds (in dB SNR) for each primary test condition and the better of the control conditions.

<p>Mean speech recognition thresholds (in dB SNR) for each primary test condition and the better of the control conditions.</p

The effect of hearing loss on dichotic benefit.

<p>Dichotic benefit (i.e., the difference between Async-D and Async-M conditions) for hearing-impaired (HI) and normal hearing controls (NH and NH_SL). Error bars indicate one standard deviation. Whereas the dichotic advantage increased significantly for NH listeners as band number increased, HI and NH_SL listeners received similar benefit at all band numbers (NH_SL group was only tested at 4 and 8 bands). Significant differences between groups are indicated by an asterisk (p < 0.05) or two asterisks (p < 0.001).</p

Masking release relative to unmodulated noise.

<p>Mean masking release is plotted for modulated noise conditions relative to the unmodulated condition for hearing-impaired (HI; left panel) normal controls with stimulus presentation at either the same intensity (NH; middle panel) or same sensation level (NH_SL; right panel). The difference in mean thresholds relative to the Unmod-M condition at 2, 4, 8, and 16 bands are plotted for the monaural asynchronous condition (Async-M; circles), the dichotic asynchronous condition (Async-D; triangles), the better of the dichotic control conditions (Control-D; bowties), and the mean of the synchronous conditions (Sync-M; dashed line). Error bars indicate standard error of the mean (n = 9 for HI group; n = 7 for NH group; n = 8 for NH_SL group). The shaded region at the bottom of each panel indicates the range over which masking release might be accounted for by reductions in masker level associated with amplitude modulation (3.2 dB).</p

Schematics of monaural and dichotic masking conditions.

<p>Primary conditions are represented on the top row, and control conditions are shown below. Only left-ear (L) schematics are visually depicted for monaural conditions, but right (R) ear conditions were also tested. As the legend indicates, each condition is represented as a 2-by-2 box in which the left and right columns represent stimulation of the left and right ears, respectively, and the top and bottom rows represent the speech and noise stimuli, respectively. In each box, frequency from 0.1 to 10 kHz is represented vertically, and a time span of 200 ms is represented horizontally. Speech is represented via spectrogram, and noise is represented in black. Amplitude modulation is performed at a rate of 10 Hz, and frequency bands are equally spaced on a logarithmic scale. The order of the primary conditions in the top row is an indication of the expected ranking in thresholds, with the worst performance starting on the left, with the Unmod-L and Unmod-R conditions, and the best performance on the right, with the Sync-L and Sync-R conditions. The numbers of bands tested per condition are given below each condition schematic.</p