Acoustic treatment planner

How it is worked out

Sabine's formula, RT60 = 0.161 × volume ÷ total absorption, with the same absorption coefficients the design studio uses (for example plaster 0.03, carpet 0.35, an acoustic panel 0.9, a seated person about 0.45 m²). CEDIA/CTA-RP22 recommends 0.2–0.5 s for home cinemas: a room within that range gets no panel count, and a room above 0.5 s gets the panels that bring it to about 0.4 s, the middle of the range, so it does not sit on the edge (the design studio and Ask the Advisor use the same rule). It is an estimate for planning: furniture, curtains and bookcases all add absorption, so measure the finished room (the REW Analyzer reads the measurements).

Where panels matter most

• First reflections on the side walls and ceiling arrive just after the direct sound and blur dialogue and imaging. Panels there, at ear height, do the most for clarity.
• Front corners: thick bass traps tame the room modes that make some notes boom.
• Back wall: worth treating when the seat is close to it.
• Not everything: a room covered in thin foam sounds dead in the treble and still boomy in the bass. Mix absorption with soft furnishings, and keep some surfaces live.

Rules of thumb: panels of 5 cm or more for broadband absorption, 10 cm or more (with an air gap) to reach lower; bass traps thicker still.