If the wall is parallel to the driver, then the sound wave is reflected back towards the driver but the reflected sound is out of phase with the initial wave as illustrated on the right.
(the wall; is; parallel to the driver) (the sound wave; is reflected; back towards the driver; T:then) (the reflected sound; is; out of phase with the initial wave; T:as illustrated on the right)
the wall the sound wave the reflected sound
is is reflected is
parallel to the driver
back towards the driver T:then
out of phase with the initial wave T:as illustrated on the right