Halving a speaker’s radiating angle doubles its critical distance.

Evidence

This is a very short distance! If the speaker is mounted in the wall, the Q increases to 2, because the speaker can only radiate into 2 π steradians; so the critical distance increases to: r RQ critical distance m cm = = × = 0 141 0 141 18 75 2 0 86 86 . — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1801

Categorization

• QUESTION: Why does halving the radiation angle snap the critical distance from 61 cm to 86 cm rather than doubling it — worth checking the square-root scaling in the RQ term.