Standing waves are everywhere, well almost. Get a hold of an SPL meter and a test CD with test tones. You will find all sorts of standing waves, echoes, peaks and reflections that interfere with the pure unadulterated signal from the speakers. Everywhere you find a sound pressure level at least say, 4 or 5 dB above the average sound pressure in the room you got a problem. Don’t be surprised to find some peaks greater than 6 dB above average. Think of it like a lot of speakers playing simultaneously, with some playing 10 times louder than your speakers when playing at moderately loud levels. Every room is different and every speaker produces different radiation patterns.
