Figure 2.

Tasks. Three sounds were presented on each trial. The listener's task was to choose the sound (signal) that was different from the other two (standards). A, In the modulation-depth-discrimination tasks (spectrotemporal shown), the signal had a shallower modulation depth (left) than the standards (middle and right). The more similar the modulation depths that could be discriminated, the better the threshold. B, In the modulation-detection task, the signal was modulated (left) and the standards were not (middle and right). The shallower the signal modulation depth that could be detected, the better the threshold.