I believe humans are insensitive to distortion until it reaches high levels especially in lower frequencies where we seem to tolerate a lot.
The Intellectual People Podcast - Ethan Winer (RealTraps)
Ethan Winer joins for an hour of explanation of room treatment and explains his views on many other audio related topics including his book The Audio Expert.
https://www.youtube.com/watch?v=yUmt8knPs0M
https://www.youtube.com/watch?v=yUmt8knPs0M