Alan, am i right in thinking that it's the same thing happening when i have a steady pink noise playing through the front speakers, with the spl meter at the LP, and when i move around the room a little, the meter registers the variations (in SPL) caused by varying reflections of my body movements?

when i'm finished calibrating my system with Audyssey, i check speaker levels with my SPL meter and the receivers' test tones, and i have to stand just outside the AV room while i do the measurements so i can get good readings on the meter.