Auditory babble as a masker of disruptive speech

Numerous studies have shown that task irrelevant background speech impairs the performance of working memory. This well established effect is related to practice in open-plan offices, where employees are potentially disturbed by the speech of their colleagues. One option to reduce the disruptive effect is masking the speech, for example by noise. In open-plan offices babble of voices might be a useful natural masker of disruptive speech. Prior studies suggest that a small number of one or two background voices cause a high level of disturbance, whereas six voices talking simultaneously produce significantly lower error rates. The aim of this study was to examine the potential benefit of background speakers placed outside the radius of distraction with regard to masking a speaker placed close to the receiver. Therefore working memory performance of subjects listening to a speaker and one to six background voices was tested. Additionally, the intelligibility of the presented speaker sentences was checked. We expected the performance to improve with the number of background voices, whereas intelligibility should decrease. The results show a significant trend towards an improvement of working memory performance when the number of babble voices grows from one to six.