Relation between sound absorption and speech intelligibility in room, part 2: Case study based on geometric simulation

Abstract

Sound absorption works for reverberation suppression and noise reduction, both of which contribute to improving speech transmission performance. In the previous paper, its combined effect was theoretically investigated to clarify the relationship among of reverberation time, average absorption coefficient and speech intelligibility indices. In this paper, a case study is first conducted to examine the applicability of the theoretical estimation of clarity C50 based on geometric simulation. In rectangular rooms with different volumes, aspect ratios and absorption distributions, impulse responses are simulated for various source-to-receiver positions, and then the distributions of the simulated C50 are compared with the theoretical values. Furthermore, a subjective experiment on speech intelligibility is conducted by using a 6-channel sound field reproduction system, where a speech signal is convolved with the simulated impulse responses under background noise conditions. The results show the correlation between the listening difficulty rating and the estimated useful-to-detrimental ratio U50.