Currently, architectural room acoustic metrics make no real distinction between a room impulse response and the auditory system's internal representation of a room. These metrics are generally based on impulse responses, and indirectly assume that the internal representation of the acoustic features of a room is independent of the sound source. However, while a room can be approximated as a linear, time-invariant system, auditory processing is highly non-linear and varies a great deal over time in response to different acoustic inputs. Listeners were presented with various signals (clicks, long-duration noise, music, and speech) convolved with impulse responses consisting of Gaussian noises with different rates of exponential decay. Listeners were asked to adjust the reverberation time of one of the signals to match the other. Analyses of the data show that the source signal has a significant influence on perceived reverberance. Also, listeners were less accurate when matching reverberation times between different signals than they were with identical signals, suggesting that predicting subjective measures of reverberance from room impulse responses faces severe limitations that cannot be neglected. Results further suggest that the auditory system does not have a well-developed temporal representation of the diffuse reverb tail.

Currently, architectural acousticians make no real distinction between a room impulse response and the auditory system’s internal representation of a room. With this lack of a good model for the auditory representation of a room, it is indirectly assumed that our internal representation of a room is independent of the sound source needed to make the room characteristics audible. In a perceptual test, we investigate the extent to which this assumption holds true. Listeners are presented with various pairs of signals (music, speech, and noise) convolved with impulse responses for different rooms. They are asked to evaluate the differences between rooms and disregard differences between the source signals. Multidimensional scaling is used to determine the extent to which the source signal influences the internal representation of the room and which room acoustical characteristics are important/perceivable for each sound type.