Diffusion and scattering continue to be hot topics in room acoustics and in particular in auditorium acoustics. It is being heavily debated how scattering due to surface roughness and room geometry relates to the level of diffusivity in a room. We suggest the Dynamic Diffusion Curve (DDC) as a tool for evaluation of the level of diffusion in an impulse response. The idea is that a high degree of diffusion is connected with a low directional trend; theoretically an ideal diffuse sound field has equal probability of any direction of propagation and thus the intensity should be low, whereas a one-dimensional propagating sound wave has a high intensity level (equal to the sound pressure level).

DDC is derived from the difference between the decay curve derived from the backwards integrated squared impulse response measured or simulated with an omni-directional microphone and the decay curve of the backwards integrated intensity impulse response, which can be measured or simulated by a combination of three intensity probes or three figure-of-eight microphones (x, y and z directions). So, DDC is a measure of the amount of non-directional energy as a function of the time during the decay process.