Reverberation time recommendations for noisy industrial workshops

Abstract

Industrial workshops or any other industrial premises where noisy machines are operated should be as acoustically absorbent as possible. On the other hand, acoustic treatments are expensive (especially when correcting existing premises), messy, and not always compatible with the implemented production processes. Therefore, there is a need for acoustic specifications to find the best compromise between cost and efficiency. In France, for noisy industrial workshops to be compliant, the regulation requires the rate of decay of sound per distance doubling (DL2) to exceed compulsory limit values, unless this does not have a significant impact on workers' exposure to noise. However, that rate of decay is difficult and time consuming to evaluate. The purpose of this paper is to provide recommendations based on reverberation time (RT), which is not only easier to measure but is also widely used. The D2L values are conventionally measured in industrial workshops together with RT values and thus a database compiling both RT and DL2 values was available. It has been used to draw up reference limits for RT values consistent with the DL2 regulation limits. These reference limits were validated by comparison with the literature and with a new set of data collected specially for the purposes of performing that comparison. The final limits are divided into four categories: compliant/non-compliant, for furnished/empty industrial workshops, using a 95/99% confidence interval. They are intended to enable the acoustic treatment of a workshop to be evaluated using a simple metric, either at the design stage or for monitoring or occupational inspection purposes.