1 Introduction
Sound as an information channel has distinct advantages over other methods of communication, making it widely-used for warnings and alerts in various contexts and environments. Auditory warning signals in user environments are, more often than not, very simple, monotone sounds. In application, they are often annoying and difficult for users to recognize and understand (Block et al., 1999; Ulfvengren, 2006) During recent time there has been an increasing interest to investigate new and more complex nonspeech sounds to convey information in critical situations (Stevens et al., 2006;
Ulfvengren, 2006; McKeown, 2005). The Sonic studio, part of the Interactive Institute in Sweden, is a research unit focusing on applied research within sound, interactivity and new technology. Sound for information-delivery is a recently started research project at the studio. One particular focus is to explore alternative methods to design warning signals for user environments. So far, a literature study has been carried to with the aim to investigate the progress which has taken place within this branch of sound design research, identify issues related to this type of research, and to point out some new potential ways to design warning signals. The objective of this paper has been to present and discuss the important findings of this study.
2 Speech and non-speech sounds
A common approach in auditory display research today is to distinguish between speech and non-speech sounds. General advantages and disadvantages of both categories of sound have been proposed. Speech-based signals may require minimal learning (Leung et al. 1997) and are suggested to have advantages over non-speech sounds in situations when the information to be conveyed is very complex, when the number of warnings in a system is very large, or when the user is not required to make a