Comparison of the smoothed spectra of two stellar twins, KIC 5295898 (with depressed modes; blue curve) and KIC 2157650 (with normal modes, nearly seen pole on; purple curve printed upside down). The width of the smoothing filter is 0.05 μHz, which is much smaller than the expected width of dipole modes if not mixed. A small shift in frequency is needed to superimpose the peaks.