Minimizing floor-reflection dips in measured curves produced no audible improvement

Evidence

Very early in my explorations of loudspeaker/room interactions I was aware of the measurable effect of the floor reflection in steady-state room curves. It seemed like a problem that needed attention, so I devoted some time to modifying loudspeakers to minimize it, and followed through with subjective evaluations. I cannot claim to have been exhaustive, but I soon became frustrated when the curves looked better but the sound seemed not to have changed very much. I moved on to other problems that were clearly audible and never returned. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1295

Categorization

• QUESTION: Why do visible steady-state response artifacts from floor reflection fail to correlate with audibility? This seems like a core puzzle in psychoacoustics worth chasing.