Evaluation of Accurate Artificial Reverberation Algorithm

Artificial reverberation algorithms aim at reproducing the frequency-dependent decay of sound in a room that is perceived as plausible for a particular space. In this study, we evaluate a feedback delay network reverberator with a modified cascaded graphic equalizer as an attenuation filter in terms of accurate reproduction of measured impulse responses of three rooms with different decay characteristics. First, the late reverb is synthesized by the proposed method and mixed with the early reflections separated from the original signal. The synthesized and measured signals are compared in terms of their decay characteristics and reverberation time values. The experiment shows that the proposed reverberator design reproduces real impulse responses well, although the decay-rate error exceeds the just noticeable difference of 5% in many cases. Additionally, perceptual qualities of the synthesized sounds were assessed through a listening test. Four qualities were tested for three room impulse responses and three kinds of stimuli. The results show that for the qualities reverberance, clarity, and distance, on average 75-79% of participants noticed only a slight or no difference between the measured and synthetic reverbs. Similar results were obtained for the speech and signing voice stimuli and the reverberation of lecture room and concert hall.