Perceptual Evaluation of Model- and Signal-Based Predictors of the Mixing Time in Binaural Room Impulse Responses

When creating virtual acoustic environments, the computational demands can be reduced by using generic late reverberation. Beyond the “mixing time,” the diffuse reverberation no longer contains details of the specific location. Therefore, a perceptually validated model for predicting the mixing time of different spaces will be helpful. This study evaluates various predictors of the perceptual mixing time using 9 different spaces. Both model- and signal-based estimators of mixing time were examined for their ability to predict the results of a group of expert listeners. For a shoebox-shaped room, the average perceptual mixing time can be predicted by the enclosure’s ratio of volume over surface area V/S and by vV, which serve as indicators of the mean free path length and the reflection density, respectively. Moreover, the “echo density profile” by Abel and Huang (AES paper 6985) can be used to predict the perceptual mixing time from measured data.