The design and implementation of non-verbal auditory warnings.

There are many common problems in the use of non-verbal auditory warnings in the working environment. They are often too loud, too numerous, and they are frequently confusing. These problems have a range of consequences, many of them serious. However, there now exist a number of guidelines and sets of experimental data that address these problems and provide fairly comprehensive solutions. In this article the underlying problems are highlighted, and the guidelines and research that have addressed the central issues of correct loudness levels and psychological appropriateness, particularly warning confusion and 'urgency mapping', are reviewed and evaluated. It is argued that a proper ergonomics approach to auditory warning design and implementation is not a luxury, but a necessity. A number of projects in which advanced, ergonomic auditory warning systems have been developed are described in detail, and some new research questions are proposed.