While the human perception of diesel engine noise has been the subject of numerous studies, the
perception of the vibrational disturbance reaching the driver has not previously been investigated.
This contribution presents the results of a recent research study performed at Sheffield University
which analysed the nature of diesel engine idle, and modelled the associated human growth function.
The results have shown that the largest component of diesel idle irregularity arriving at the steering
wheel is amplitude modulation of the firing frequency and that the human subjective response grows
with a power exponent greater than 1.0 for modulation values greater than 0.2
