Sabine Equation

The Sabine equation is the most widely used formula for predicting reverberation time, expressing RT60 as a function of room volume and total absorption area. Developed by Wallace Clement Sabine in 1898, it assumes a perfectly diffuse sound field with uniform absorption distribution. The equation is documented in ISO 3382-2:2008 Annex A.1. While accurate for rooms with relatively low and evenly distributed absorption (average absorption coefficient below 0.3), the Sabine equation overestimates reverberation time in highly absorptive rooms because it does not account for the reduced energy available after each reflection. For rooms with average absorption coefficients above 0.3, the Eyring equation provides better accuracy. Despite its limitations, the Sabine equation remains the default calculation method in building regulations and acoustic design guides worldwide due to its simplicity and conservative predictions.