The Millington-Sette equation reduces to the simpler Sabine equation when absorption is below 0.3

Evidence

Equation A5.3 is also known as the Millington-Sette equation. Although Equation A5.3 can be used irrespective of the absorption level, it is still more complicated than the Sabine equation, and if the absorption coefficient is less than 0.3, it can be approximated very effectively by it, as discussed previously. Thus, in many contexts, the Sabine equation, Equation A5.1, is preferred. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2861

Categorization

• XREF: Names the Millington-Sette equation and ties it back to the Sabine equation from earlier chapters.
• SHARE: A nice practical trivia point for someone who designs or specs room acoustics: there is a numerical threshold (α = 0.3) below which the complicated formula can be safely replaced by the simple one.