Rate at which Echo Density Builds

• After the initial reflection, the rate at which echoes reach the listener increases rapidly.
• A listener can distinguish differences in echo density up to a density of 1 echo/ms:
  • the amount of time required to reach this threshold influences the character of the reverberation (  100 ms in a good situation).
  • this time is roughly proportional to the square root of the volume of a room (small spaces are characterized by rapid buildup of echo density).