Surface absorption can override the usual ranking of room mode strengths

Evidence

However, this is not always the case, as a tangential mode in a room with four reflecting surfaces could be stronger than the axial mode between the other two absorbing surfaces. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2011

Categorization

• QUESTION: How do real listening rooms deviate from the textbook axial > tangential > oblique ordering?