Additional sound capabilities in visually advanced simulators may offer researchers and practitioners better resources to evaluate in-vehicle auditory signals and advanced auditory displays. In the first part of the present report, the implementation of a new audio system in the Scania truck cabin for the driving simulators II and III at the Swedish National Road and Transport Research Institute (VTI) is described.

The new audio software is based on the Open Audio Library (OpenAL) implementation for the Macintosh Operating System OS X. It communicates with the existing simulator software using the Open Sound Control (OSC) standard. The remaining program code is open, which offers the possibility of adapting the audio system to future demands and specific needs of partners within the competence centre ViP (Virtual Prototyping and Assessment by Simulation).

Another aim of the present project was to investigate the potential of urgent alarms to raise annoyance and negatively affect drivers’ subsequent responses to unrelated, critical events on the road. While performing a simulated driving task, truck drivers received two types of warnings that were designed to differ significantly in perceived urgency. Several times in the trial an unexpected event occurred just seconds after drivers were presented with an unrelated warning, and the drivers had to brake immediately to avoid a collision. The results indicate that acoustic characteristics and semantic meaning may impact the perceived annoyance of in-vehicle warnings. Furthermore, the participants who received a high-urgency warning braked significantly harder and tended to brake later than the drivers who received a low-urgency warning.

The simulator study was also used to validate the reliability of the new audio system.