Energy Decay Curve

For measuring and defining reverberation time $t_{60}$ , Schroeder introduced the so-called energy decay curve (EDC) which is the tail integral of the squared impulse response at time $t$ :

$$\hbox{EDC}(t) \isdef \int_t^\infty h^2(\tau)d\tau$$

Thus, $\hbox{EDC}(t)$ is the total amount of signal energy remaining in the reverberator impulse response at time $t$ . The EDC decays more smoothly than the impulse response itself, and so it is more useful than ordinary amplitude envelopes for estimating $t_{60}$ .