The aim of the present study was to investigate cognitive, emotional, and physiological effects of two background noise conditions (high noise: 51 LAeq and low noise: 39 LAeq) during work in a simulated open-plan office, followed by four restoration conditions (river movie with sound, only river sound, silence, and office noise) after the work period. Students (N = 47) went through one practice session and two experimental sessions, one each with the low and high noise conditions. In each experimental session they worked for two hours with tasks involving basic working memory processes. We also took physiological measures of stress (cortisol and catecholamine) and self-reports of mood and fatigue. The results showed that the participants remembered fewer words, rated themselves as more tired and less motivated in high noise compared to low noise. The participants showed high levels of cortisol when they arrived to the experimental session and they had a significant (p <.001) decline in both noise conditions after two hours of work. An identical decline was shown in the norepinephrine levels (p < 0.001). The restoration phase also indicated that the sound conditions may promote different restorative experiences. To conclude, the present study showed that noise level can be of importance for working memory performance and subjective feelings of tiredness and motivation in an open-plan office and that varying sound conditions may promote different restorative experiences.

When spoken information is presented in unfavourable listening conditions a larger part of the available and limited information processing resources must be allocated to the identification of the words spoken. This leaves fewer resources for the further processing of the speech (the interpretation and storing of the information). In such circumstances understanding and memory of speech might be impaired although each word has been correctly heard. This hypothesis was confirmed in two previous studies where memory of a word list was shown to be impaired when presented in unfavourable listening conditions: unfavourable signal/noise ratio (Kjellberg, Ljung & Hallman, 2008) and a too long reverberation time (Ljung & Kjellberg, in press). Kjellberg et al. also found that the noise effect was weaker the better the working memory capacity (as measured with a reading span task).

This paper reports two experiments on the effects of degraded speech signals on memory for spoken lectures. Experiment 1 showed that broadband noise impairs university students’ memory for a spoken lecture, even though the participants heard what was said. Experiment 2 showed that reverberation has detrimental effects to school adolescents’ memory for spoken lectures, similar to broadband noise. The results suggest that poor listening conditions (resulting from background noise and/or long reverberation time) impair memory and learning, even if the conditions allow the listeners to hear what is said. Since the goal for students and pupils attending to lectures is to remember the lecture rather than just hearing what is said, the results presented here indicate that standards for acceptable signal-to-noise ratios and reverberation times in buildings designed for learning should consider the distinction between speech intelligibility and memory. Standards should be based on memory criteria instead of intelligibility criteria.