# Quickly generate Local Decay Times and validate Eyring and Sabine results for the room RT

The Local Decay Time feature of EASE allows you to perform a quick check of local Reverberation Time figures through a special Ray Tracing technique, producing more accurate local results than the statistical formulas in a short time frame.

The calculations can be performed at several locations in the room simultaneously.

The motivation:

Both Eyring and Sabine conceived generalized formulas for the calculation of the RT based on the assumptions that the absorbing materials are homogeneously distributed over the room surfaces, and that the reverberant sound field in the room is nearly diffuse. From the equations a single set of frequency dependent RTs are calculated for the room.

The formulas are extremely useful in a wide range of applications and accepted worldwide. However, the assumptions above are true to only a certain degree, depending on the circumstances. In fact, the Reverberation Time in a room can vary greatly with position, due to the geometrical properties of the room and to the distribution pattern of acoustic materials! For instance, a listener seated under a balcony might not have the same subjective feeling of sound persistence as a listener located at the center of the hall. The Local Decay Time routine lets you immediately analyze this effect.

How it works:

EASE sends out a customizable number of rays from the selected listener positions. As the rays travel through the room, the program keeps track of their energy and time. Each ray is computed for 60 dB loss and averaged with all other rays. This average is then used to predict the Local Decay Time at each specific location.