Music Production
Estimate room RT60 from volume and absorption.
Helpful for studio acoustics planning.
RT60 (reverberation time at 60 dB) is the international standard for measuring reverberation in acoustic spaces. It quantifies how long it takes for sound to decay 60 decibels below its initial level after the sound source stops. RT60 is the most important metric for characterizing a room's acoustic character and is essential for predicting how spaces will sound. Different rooms have different RT60 values at different frequencies—high frequencies typically decay faster than low frequencies due to air absorption and material characteristics. RT60 affects recording quality, mixing accuracy, and the perceived 'liveness' of a space. Professionals use RT60 measurements and calculations to design recording studios, concert halls, and other critical listening environments. Understanding RT60 helps engineers match reverb settings to the acoustic characteristics of their spaces and make informed treatment decisions.
RT60 is calculated using the Sabine formula, which relates room volume, surface absorption, and decay time. You input room dimensions, materials for each surface, and whether there's air conditioning or HVAC noise. The calculator computes volume, estimates absorption coefficients for each material at different frequencies, and calculates RT60 at octave bands (125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz). The frequency-dependent results show realistic decay characteristics, as different frequencies decay at different rates in real rooms.
RT60 = 0.161 × V / (A), where V is room volume in cubic meters and A is total absorption in sabins. One sabin = 1 m² of material with absorption coefficient of 1.0. For a 100 m³ room with 20 m² of absorption: RT60 = (0.161 × 100) / 20 = 0.805 seconds. Adding absorption increases the denominator, reducing RT60.
Target 0.3-0.5 seconds, with consistency across frequencies. This provides neutral acoustics without excessive reverberation or deadness. Too much RT60 (over 0.8s) makes mixing difficult; too little (under 0.2s) sounds unnatural.
Different materials absorb different frequencies differently. High frequencies are absorbed more readily than low frequencies. This frequency dependence is realistic and important for accurate acoustic treatment planning.
Use a sound level meter and signal generator. Play a test tone, stop abruptly, and measure how long the sound takes to drop 60 dB. Modern smartphone apps can estimate RT60 from hand claps, though they're less accurate than proper instruments.
No, natural-sounding rooms have slightly longer RT60 at low frequencies. However, extreme variations (RT60 of 2 seconds at 100 Hz but 0.3 seconds at 4 kHz) sound unbalanced. Aim for modest frequency variation, typically 0.5-1 second difference between lowest and highest octaves.
