Combined analyses of the effects of background speech with varying intelligibility onto objective measures of performance and subjective assessments

Recently, a lot of emphasis has been put onto the investigation of effects of background speech on cognitive performance and the economic impacts resulting thereof. Negative effects of background speech on short-term memory performance have been shown in several laboratory studies. It is assumed that these results are of great practical importance to employees' performance in open-plan offices. The Speech Transmission Index (STI), a measure of speech intelligibility, is considered to be a suitable physical set value to predict the decline of performance. However, effects on cognitive performance are not the only issue to discuss with regard to the presence of background speech in open-plan offices. It has already been shown that the results of subjective assessments and objective measures of performance do not necessarily match. Employees may be able to compensate for performance effects by an increase of effort but in turn perceived workload may increase. Additionally background speech can reduce the feeling of privacy. These effects may not be directly visible but need to be considered in the long term as job satisfaction may decline and absenteeism may increase. Thus being able to perform well, does not necessarily mean that everything is fine. A holistic approach needs to incorporate both, effects on performance as well as on well-being. The reported results consider the effects of background speech varying in intelligibility (STI) onto both, objective and subjective measures. It is shown that subjective assessments, e.g. of workload, disturbance, as well as privacy and objective measures of performance correlate with the STI.