Abstract
Laboratory simulation of sound and vibration in cars have been used to investigate the effect of infra-sound on ride comfort caused by steady vibration and impact harshness. In the first experiment using steady vibration, subjects sitting on a seat attached to vibrators were asked to evaluate the magnitude of discomfort caused by sound. The results showed that audible sound and vibration reduced the discomfort caused by infra- and low frequency sound. In the second experiment using shock due to impact harshness, subjects were asked to judge the magnitude of shock caused by transient vibration transmitted to subjects' bodies and total discomfort caused by both shock and sound. It was shown that sound did not affect evaluations of the magnitude of shock, but that evaluations for total discomfort were influenced by sound, and in particular by infra-sound.
