Cross-Modality Matching of Loudness and Perceived Intensity of Whole-Body Vibrations

In this study, two experiments were conducted to determine the point of subjective intensity equality (PSE) of pure tones and sinusoidal whole-body vibrations (WBV) at various frequencies (50Hz, 100Hz and 200Hz). In these experiments, sounds and vertical vibrations were simultaneously presented to subjects using circumaural headphones and a flat hard seat. In total, 10 participants were subjected to tones with a fixed loudness level (40 phon, 60 phon, 80 phon and 100 phon). The participants were asked to match the intensity of the vibration to the loudness of the tone, using the method of adjustment. In the first experiment, the participants were subjected to a vibration and tone with the same frequency. Alternatively, in the second experiment, the frequency of the vibration was maintained at 50Hz, while that of the tone was varied. The results revealed that a 20 phon increase in loudness level resulted in a 5-6 dB increase in matched acceleration level at loudness levels greater than 40 phon. This result was reproducible with small intra-individual variations; however, large inter-individual differences were observed.