Figure 2
From: Active control of broadband sound through the open aperture of a full-sized domestic window
A-weighted energy-average spectrum of 100 Hz to 1 kHz band-limited (a) gaussian white noise, (b) highway noise, (c) MRT pass-by noise, and (d) aircraft fly-by noise, before active control 
, after active control 
, and with windows fully shut without active control 
.
