Removing floor reflections makes sound unnatural to human listeners

Evidence

Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative—unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1297

Categorization

• QUESTION: What range of floor-reflection timing and spectral content does the brain treat as natural? Could relate to head-related transfer function experience.
• ADDENDUM: Directly relevant to the ‘Grafting & Growth’ article’s theme of natural infrastructure — here, the floor as an ever-present natural acoustic element the brain is calibrated to.