A Driving Simulator Study to Examine the Role of Vehicle Acoustics on Drivers' Speed Perception

In recent years, there has been a desire by vehicle manufacturers to reduce the in-cab noise of vehicles, in order to improve driver comfort and enhance the enjoyment of in-vehicle entertainment systems. This reduction of in-cab noise is accompanied by policy initiatives to reduce transport related noise by implementing low noise road surfaces. However, it is not known how such reductions in the availability of auditory cues affect drivers’ ability to judge speed, and there is a danger that drivers will increase their speed, to compensate for the absence of auditory cues. In this study, drivers were required to maintain speed at 30 and 70 mph, in the absence of a speedometer, with and without accompanying vehicle noise. Results showed that drivers’ ability to maintain the correct speed profile was much more variable in the absence of accompanying vehicle noise and this variation was found to be higher when drivers were asked to travel at higher speeds of 70 mph. Drivers were also found to travel faster than the required speed in the absence of vehicle noise, although their ability to maintain speed was generally worse at 70 mph, even in the presence of auditory cues.