Figure 1.

Schematic of the quilting algorithm and example stimuli. (a) Quilting algorithm. A source signal is divided into equal-length segments (ranging from 30 to 960 ms). Segments are then reordered subject only to the constraint that they best match the segment-to-segment changes in the cochleogram of the source signal. Segment-to-segment changes were calculated from the 30-ms sections at the borders of each pair of segments, indicated by the dashed lines. In the equation defining the segment-to-segment change, $C_n^R(t,f)$ and $C_n^L(t,f)$ denote the cochleogram value at time t and frequency f of the right and the left border of the nth segment, respectively. (b) Example cochleograms of quilts made from 30- and 960-ms segments, from each of four source signals: German speech, a modulation-matched control signal, a co-modulation–matched control signal and noise-vocoded German speech. Quilts of long and short segments were not markedly different in visual appearance, but sound notably distinct in all cases.