Acoustic climate inside a canteen and mitigation solutions

The acoustic environment inside a canteen is an important feature to guarantee speech intelligibility and speech privacy, as well as to reduce the exposure levels. Unfortunately this aspect is not always properly taken into account as others, like cleanliness. This paper describes the case-study of the canteen at the National Agency for Environmental Protection (APAT), having a capacity of 220 seats. The acoustic environment has been characterized by measuring the main acoustic descriptors for speech intelligibility (Reverberation Time, STI, C80 and D50) and evaluating the noise exposure levels for the users. The comparison of the results with the recommended values showed a bad situation, especially in the speech frequency range, which requires acoustic corrections to improve the quality of the acoustic environment. To identify these corrections a numerical model of room acoustics, implemented on a commercial software, has been used to evaluate the effects produced by different corrections. The proposed correction improves the acoustic performances up to a good level, without modifying the structural parts and existing walls. Moreover, the solution allows to maintain the hall's usability without obstructing user mobility, screening natural lighting and reducing number of seats.