Why Sabine over-predicts a dead room, and what Eyring fixes
Sabine's equation assumes sound is absorbed continuously. In a heavily treated room it is not, and the prediction comes out a third long.
Notes
Journal
Working papers: measurements we found worth writing up, arguments we keep having with architects, and the occasional room that refused to behave.
What a Schroeder diffuser’s well depths are actually doing
The wells are not decoration and the sequence is not arbitrary. It is a number-theoretic trick for making a wall scatter evenly.
Below the Schroeder frequency, proportion beats treatment
A small room does not have a reverberation time in the bass. It has a handful of resonances, and where they fall was decided when the walls were drawn.
Measuring a hall empty, and again full
An empty auditorium and an occupied one are different rooms. Everything hangs on how large the difference was allowed to be.
Insulating a wall is not treating a room
The single most common misunderstanding we are asked to correct — and the reason foam on a party wall has never once worked.