Convention Paper
Aspects of Reverberation Echo Density
AES Convention 123 · Paper 7163 · October 2007
Abstract
Echo density, and particularly its time evolution at the reverberation impulse response onset, is thought to be an important factor in the perceived time domain texture of reverberation. In this paper, the psychoacoustics
of reverberation echo density is explored using reverberation impulse responses synthesized via a Poisson process to have a variety of static and evolving echo densities. In addition, a recently proposed echo density measure called the normalized echo density, or NED, is explored, and related via a simple expression to
echo density specified in echoes per second using echo patterns with static echo densities. A continuum of perceived time-domain texture was noted, from “sputtery” around 100 echoes per second to “smooth” above about 20,000 echoes per second, at which point it was perceptually identical to Gaussian noise. The character of the reverberation impulse response onset was explored for various rates of echo density increase, and ranged from “sputtery” for long mixing times to “instantly smooth” for short mixing times.
