Influence of source directivity on noise level into industrial halls

In order to improve the accuracy of a room acoustical software, this study was aimed at simply characterizing the directivity of several noise sources, then taking into account this directivity in the processing, and finally assessing its influence on the noise level radiated into industrial halls.
Complete characterizations of both a test-source and a table-saw have been achieved in a hemi-anechoic chamber. Then, a simple characterization method has been achieved on two wood-working machines in a production hall: a planing machine and a surface-planing machine. The directivity of the test-source was then used as an input parameter of the room acoustical software for simulating a large set of industrial halls. Measurements were also achieved with several sources in an empty building and in a building containing a lot of scattering objects.
The measurements and the simulations show that the radiated field is nearly the same whatever the source directivity as soon as the building is full of objects. These results are independent from the source directivity or the acoustical treatment of the hall. The directivity of the wood-working machines is generally low. The influence of this directivity on the noise field is not negligible at the workplace but remains low in the rest of the hall whenever it is not empty.
The directivity of the machines measured in this study is a second-order factor for the noise exposure of the workers staying far from the machines. There is no requirement to introduce the directivity of such noisy machines in the room acoustical software in the case of a use for improving the efficiency of the acoustical treatment of the hall.