Fig. 8.

“Chunk slopes,” in milliseconds per week, were determined by the absolute values of changing chunk duration (see Materials and Methods). These slopes reflect changes in chunk duration during the first 8 weeks after deafening; the larger the magnitude of the slope, the more chunk duration changed. Each bird is represented by a singlesymbol, and the code is as follows: ●, young adult (n = 6); ▪, middle-aged adult (n = 3); and −, old adult (n = 7). The slope of the young birds is consistently above that of the other two age groups. The highest value corresponds to a bird deafened at 81 d of age.