Not only is it important to know how large the overall change in vibration should be for occupants to perceive an improvement in comfort, but also how large this change should be in specific frequency bands. Relative difference thresholds (RDT) of primary (0.5-4 Hz) and secondary (9-80 Hz) ride are estimated for 14 automotive engineers seated in a vehicle on a 4-poster test rig over two roads. Resulting stimuli differed in magnitude and spectral shape. The median RDTs estimated for primary and secondary ride were 16.68% and 13.82% on the smooth road, and 9.50% and 24.67% over the rough road. Statistically significant differences were found in the medians of the RDTs between (1) primary and secondary ride on the two roads and (2) the two roads for changes in the primary and secondary ride, suggesting that Weber's law does not hold.
Keywords: Difference threshold; multi-axis vibration; ride comfort; vibration-induced discomfort; whole-body vibration.
Relative difference thresholds of primary and secondary ride are estimated that can be used to evaluate whether modifications to vehicle characteristics result in perceivable changes of vehicle vibration. Results suggest that Weber’s law does not hold implying that relative difference thresholds should be used that closely match the stimuli characteristics.