I was making some recordings of bass frequencies to check the response of my controll room. While I was setting up the mic in different positions round the room I had a 100Hz sine I generated in soundforge running on my K-ROK monitors fairly loud. I was getting the expected peak & cancellation effect as I walked round the room...Anyway, after about 10mins I just paused soundforge and immediately played a track I had completed an hour earlier. The only way I can explain the effect is by comparing it to coming out of a cinema on a sunny day. The mix was bright - full of detail as I remembered it, but now the bass end sounded lousy. I could pinpoint the eq needed to correct the lack of focus on the bass & kick in secconds. The 'clarity effect' died away in a couple of minutes. Has anyone here ever noticed this?