RT60
Definition
The time it takes for sound in a room to decay by 60 decibels after the source stops. RT60 is the standard measurement for characterizing the reverberant properties of an acoustic space. A shorter RT60 indicates a drier, more controlled room; a longer RT60 indicates a more reverberant space.
In Simple Terms
How long sound lingers in a room after it stops. A tiled bathroom has a long RT60 — sound rings for seconds. A carpeted bedroom has a short one — sound dies quickly. Mixing rooms aim for an RT60 around 0.3–0.4 seconds: controlled but not dead.
In Practice
A mixing room with an RT60 of 0.3 seconds provides accurate monitoring conditions. A concert hall with an RT60 of 2.0 seconds provides the lush, reverberant acoustic that enhances orchestral music but would be disastrous for critical mixing decisions.