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RT60 Room Acoustics

Estimate how reverberant a room is from its dimensions and surface type, and how hard it will fight your PA. Updates live as you type.

7 · RT60 Room Acoustics

How reverberant the room is, and how it'll fight you.

Sabine: RT60 = 0.161 × Volume ÷ (Surface area × absorption). Over ~1.5 s is a fight, add delays, tighten dispersion, point away from hard walls.

About this calculator

Estimate how reverberant a room is from its dimensions and surface type, and how hard it will fight your PA. Updates live as you type.

Questions

What is RT60?

RT60 is the reverberation time: the number of seconds for a sound to decay by 60 dB after the source stops. It is the single most useful number for how live or dead a room is. Speech stays clear up to around 1 second; much beyond 1.5 seconds and a room starts smearing music and lyrics.

What is the Sabine formula?

RT60 equals 0.161 times the room volume in cubic metres, divided by the total surface area times its average absorption coefficient. Hard surfaces absorb little (around 0.05), carpet and a crowd more (around 0.12), drapes and treatment more again (0.25 and up), so the room gets drier as absorption rises.

How do I tame a reverberant room?

You cannot change the building on the night, so control what the PA throws into it: tighten speaker dispersion, point boxes away from hard rear walls and ceilings, use delays so you can turn the mains down, and lift any soft furnishings or bodies that add absorption. Reducing reflected energy is what restores clarity.

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