In this paper we highlight the importance to take into account the variability of acoustic parameters with the occupancy level. It is important from an academic point of view to interpret the non-monotonic subjective appreciation of the effect of room occupancy level on the comfort and vocal messages intelligibility. This is particularly significant for acoustic engineers in real time estimation of acoustic parameters for public address sound systems such as those used in railway stations. To illustrate this, we consider the case of a university campus restaurant as a typical confined public establishment with different occupancy levels. As expected, a monotonic decrease of the reverberation time (T60), and a monotonic increase for sound clarity (C50 and C80) and sound definition (D50 and D80) are found when the occupancy level increases. In contrast, a non-monotonic variation is observed in the evolution of the octave band mixing time (MT) as the occupancy level is increased. The mixing time is important for the estimation of early to late reverberation ratio known to be highly correlated with speech intelligibility. We use I-SIMPA: open source software for 3-D sound propagation modeling of the considered space. The calibration is made through impulse responses measured when the restaurant is empty. On-line/off-line acoustic modeling of spaces with occupancy level consideration is therefore important to take into account the monotonic/non-monotonic dynamic room acoustic parameters changes as they are closely related to the reverberation effect on comfort and sound intelligibility.

Authors: Mzah, Yosra; Maarfi, Seddik; Ghozi, Raja; Jaidane, Meriem
Affiliations: Ecole Nationale d’Ingénieurs de Tunis, Tunis, Tunisia; CEA LinkLab, Telnet Innovation Labs, Ariana, Tunisia(See document for exact affiliation information.)
AES Conference: 60th International Conference: DREAMS (Dereverberation and Reverberation of Audio, Music, and Speech) (January 2016)
Paper Number: 7-2
Publication Date: January 27, 2016
Subject: Paper Session 7

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