A sharp resonant peak in a room’s steady-state curve predicts prolonged bass ringing.

Evidence

In Figure 14.15(c) it can be seen that the reduced frequency resolution of the waterfall plot has smoothed the 42 Hz resonant peak seen clearly in (b). However, the reward is that we are able to see the prolonged ringing as time moves forward in the waterfall. A sharp resonant peak in the steady-state room curve correlates with significant ringing. The bass was intolerably boomy within 0.5 m of the wall. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1572