Fig 1.
Examples of idealized magnitude spectra for stimuli in three conditions.
In all cases the spectral modulation depth is 20 dB. The top and bottom rows show standard and target stimuli, respectively. The leftmost column shows 0.5 rpo for a condition in which all 8 bands are target bands. The middle column shows 4 rpo for a condition in which target bands are centered on 0.5 and 1 kHz, and the remaining bands are unmodulated noise (masked condition). The rightmost column shows 2 rpo for a condition in which the target is a single band centered on 2 kHz, and the remaining bands are scaled to zero (quiet condition). The +/- 6-dB interval rove is not depicted in this figure.
Fig 2.
Psychometric functions by rate.
Example fits are shown for one listener. Functions are plotted on dB modulation depth in the left panel and log(dB) in the right panel. Color reflects spectral modulation rate.
Fig 3.
Thresholds as a function of spectral modulation rate for two tasks.
Thresholds in dB are plotted for detecting spectral modulation and spectral modulation phase reversal. Error bars show one standard deviation, computed in log units.
Fig 4.
Thresholds for one- and two-band targets as a function of band center frequency.
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.
Fig 5.
Examples of idealized magnitude spectra for 0.5 and 2 rpo.
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.
Fig 6.
Correlation between spectral modulation depth and correct detection of modulation phase reversal.
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.
Fig 7.
Thresholds as a function of spectral modulation rate.
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 Fig 3).