Contribution to the study of the psychological effects of speech noise in open plan offices

It is now accepted that speech noise is the main source of discomfort for employees in open offices. The objective of this work is to evaluate the psychophysiological effects of intelligible speech on employees performing one or more tasks. To meet this objective, two experiments were carried out.
The first is to evaluate the decrease of performance (DP) during a seriel memory task for high intelligibility values. The acoustic indicator chosen is the STI (Speech Transmission Index). The results of the study on fifty-five participants show an effect of STI on DP. However, this experiment has limited ecological validity since it is of short duration and is limited to a very specific task.
The purpose of the second experiment is therefore to develop laboratory tests closer to open office working conditions and to study the effect of intelligible speech on psychological indicators. Thirty-nine participants participated in this experiment. Several measures such as psychological fatigue, sound discomfort and mental workload have been performed. Participants were subjected to three different noise conditions (stationary noise, modulated noise and speech) for three days. Each day, the participants did their work by being exposed to the same sound condition for 6h45min. The results show an effect of speech on the psychological state of participants. Speech seems to be the most tiring and annoying source of noise. It also leads to an additional mental load.
Beyond the results of these experiments, the psychological models used in this thesis can be adapted to conduct in-situ surveys to assess and prevent the psychological risks associated with noise in open offices.