Laboratory-based experiments were conducted to
evaluate the effect of the frequency and scale of
transient vibration events on the human detection of
road surface type by means of steering wheel vibration.
The study used steering wheel tangential direction
acceleration time histories which had been measured in
a mid-sized European automobile that was driven over
three different types of road surface. The steering
acceleration stimuli were manipulated by means of the
mildly non-stationary mission synthesis (MNMS)
algorithm in order to produce test stimuli which were
selectively modified in terms of the number, and size, of
transient vibration events they contained. Fifteen test
participants were exposed to both unmanipulated and
manipulated steering wheel rotational vibration stimuli,
and were asked to indicate, by either “yes or no”,
whether the test stimuli was from a target road surface
which was displayed on a board. The findings suggested
that transient vibration events play a key role in the
human detection of road surface type in driving
situations. Improvements of up to 20 percentage points
in the rate of correct detection were achieved by means
of selective manipulation of the steering vibration
stimuli. The results also suggested, however, that no single setting of the MNMS algorithm proved optimal
for all three road surface types that were investigated
