Peristimulus histograms for a single-unit recording in response to the set of AM songs spanning the range of time–frequency scales between 0.5 and 64 msec. The responses to AM songs generated with time windows of >64 msec were similar to those obtained at 64 msec. The stimuli started at t = 2 sec and lasted ∼1 sec. This single unit and song were from bird zfa_18. This neuron is the same as that of Figure 5. Thesymbols (*, ♦) indicate the time–frequency scale that gave the best neural response (*) and the best discrimination among songs (♦) (see Figs. 6, 8, 10).