Reverberant sound stays constant across a room while direct sound falls with distance

Evidence

The reverberation part of the sound in a room behaves differently compared with the direct sound and early reflections from the perspective of the listener. The direct sound and early reflections follow the inverse square law, with the addition of absorption effects in the case of early reflections, and so their amplitude varies with position. However, the reverberant part of the sound largely remains constant with the position of the listener in the room. This is not due to the sound waves behaving differently from normal waves; instead, it is due to the fact that the reverberant sound waves arrive at the listener from all directions. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1746

Categorization

• XREF: Connects to the direct-sound vs. reverberant-field distinction that underpins critical distance and clarity in room acoustics; relevant to why space perception shapes listening.
• QUESTION: Worth chasing: how far does a listener have to move before the constant reverberant field noticeably dominates the decaying direct sound?