Group Delay

Group delay measures how much time different frequencies take to pass through a filter or speaker. If 1 kHz takes 2ms and 100 Hz takes 20ms, the bass arrives 18ms after the midrange — smearing transient attacks and blurring imaging. Linear-phase systems have constant group delay (all frequencies delayed equally); minimum-phase systems have frequency-dependent group delay.

Group delay is most audible in the bass region where it can exceed 10–20ms in ported speakers. Sealed speakers have lower group delay. In room acoustics, room modes create massive group delay at resonant frequencies — another reason bass traps are essential.