Calculating speech noise exposure indicators in the tertiary sector

Through this study, two focuses are being considered for making progress in reducing sound discomfort in open-plan offices. The first focus for progress relates to developing calculation and prediction tools making it possible, as of the design stage, to obtain relevant indicators on the quality of the ambient sound that is conducive to performing work tasks requiring good concentration. The second focus relates to understanding the consequences on performance and on perceived tiredness or fatigue related to daily exposure to speech noise, which is the noise that is considered to be the most disruptive and annoying in open-place offices.
Regarding design tools, firstly there are now simple rules based on physical indicator target values that are measurable at the workplace (with the premises empty). These rules need to be improved in order to take into account the activity of the people, which is the main cause (apart from the acoustic quality of the materials) of good or poor ambient sound quality. Secondly, it is possible to use the INRS simulation software “RayPlus”, which is capable of predicting propagation of the acoustic field in a room, even though, in its current form, like all of the existing modelling tools, that software only supplies sound intensity values at various points of the empty room, i.e. the room without its occupants. Regarding exposure to speech noise, very few studies currently exist. Most of the work for analysing the influence of ambient noise on cognitive load relates to short-term laboratory experiments.
For the first focus of the study, a phase for identifying indicators that are relevant for assessing the quality of ambient sound will be conducted, at the end of which the RayPlus software will be upgraded, by incorporating the results of that analysis. Implementation of the new indicators will be validated by laboratory tests or by comparisons with workplace measurements. These new functions and features will constitute the basis for a new version of the software. The second focus will be conducted with the help of the Laboratoire de Vibration et Acoustique (Vibration and Acoustics Laboratory) of the INSA (National Institute of Applied Sciences) of Lyon, and in particular through setting up a thesis. The PhD student's assignment will be to define a relevant approach for assessing exposure to speech noise through subjective and objective measurements at the workplace, and through long-term laboratory testing.
This study will lead to presentations at conferences and to publications in international journals.