Impacts of Reverberation Time, Absorption Location and Background Noise on Listening Conditions in Multi Source Environment

This paper is part of a PhD research project focusing on the prediction of the acoustical quality in living rooms and workspaces in institutions for mentally challenged people. One of the important activities in these rooms is simultaneous conversations. In this respect, the speech intelligibility index (STI) needs to be improved. The impact of the reverberation time (RT), the distribution of the absorptive materials and the introduction of a screen on STI are discussed briefly .However, these objective parameters have to be assessed through subjective judgement. Auralizations of the multi source environment are done according to different reverberation and absorption (with and without a screen) conditions. Then listening tests with the subjects are accomplished. The results indicate that the judgment of reverberation; loudness and type of noise source and its impact on speech intelligibility, listening effort and noise distraction, are a central issue. Lower RT values help for better speech intelligibility and introduction of a screen is an effective element for obtaining a lower noise level. However, the interaction between objective and subjective parameters shows some variance. The type and content of the noise source have an important impact on the subjective perception for a noise source of equal sound power. For all calculations, a computational model is used: ODEON 7.0.