A consideration of the relationship between subjective unpleasantness and body surface vibrations induced by complex low-frequency noise

摘要

To investigate the relationship between subjective unpleasantness and body surface vibrations induced by complex low-frequency noise, we performed two experiments. In Experiment 1, we used seven types of low-frequency noise stimuli: 2 pure tones (31.5 and 50 Hz) and 5 complex noises composed of the pure tones. In Experiment 2, we used seven types of noise stimuli in which a 31.5-Hz tone was replaced with a 25-Hz tone. The sound pressure level of each noise component in the noise stimulus was equal to or higher than 90 dB(SPL). The body surface vibrations were measured at the right and left anterior chest, and the right and left anterior abdomen of male subjects. Subjective unpleasantness was rated on a scale of 1 to 5, and correlated with the vibration acceleration levels (VALs) of the vibrations measured on the body surface. As a result, it was found that the ratings of the unpleasantness were, on the whole, in significant correlation with the VALs. In addition, we estimated the 'suitable' frequency-weightings for the VAL to optimize the correlation with the unpleasantness. The results of the estimation were not conclusive but, based on a reasonable hypothesis, consistent with the, results of another study in which low-frequency pure tones were used as the noise stimuli. These results supported the idea that not only the loudness of the noise but also the vibrations, induced by the noise contributed to the subjective unpleasantness of persons exposed to high-level low-frequency noise.