Signal perception during performance of an activity under the influence of noise

Usually the perception of acoustic signals is investigated under conditions where the subjects pay full attention to the signals. It can be assumed that the threshold of signal perception is much higher if the attention has simultaneously to be focused on the execution of any kind of other activity. In the following experiment subjects have to perceive acoustic signals while solving different arithmetical tasks at the same time. The results (number of perceived signals, number of arithmetical tasks solved, reaction time, and solving time) show that the threshold of signal perception rises while other tasks are being performed simultaneously. Consequences for the recognition of warning signals in occupational safety and in traffic conditions are discussed.