Results for neural synchronization. (a) ITPC, (b) mean ITPC at the stimulation frequency (4 Hz) and at the 4 Hz fundamental/harmonic series (4:4:20 Hz), and (c) the average ratio (Q) for synchronization to the stimulation frequency (F0) and the harmonics (F1:F4) are plotted for each age group (younger, older) and envelope shape (ramped, damped). Topographies in (a) represent mean ITPC at the 4 Hz stimulation frequency and are shown for each envelope shape (ramped, damped) and age group (younger, older). Error bars indicate SE. *p < 0.05.