In noise reduction, having read that directivity index is used to reduce diffuse noise and white noise gain reduces spatially white noise, I would like to know the difference between both the noise types. Is it that diffuse noise is identically distributed but not white? Hope some one could help :)
In a diffuse noise field the noise energy flows in all directions with equal probability. This does not mean that the noise at one point is uncorrelated with the noise measured at another point. On the other hand, for spatially white noise, also called incoherent noise, the noise signals at two different points in space are always uncorrelated.
An example for a diffuse noise field is noise in a car or in an office. An example for spatially white noise would be amplifier noise in a microphone array, where the noise in each channel is independent of the noise in other channels.