Effects of noise level and type of music on listening level of music through headphones in a train car

摘要

Although portable music devices are useful for passing time on trains, exposure to music using headphones for long periods carries the risk of damaging hearing acuity. The aim of this study is to examine the listening level of music through headphones in the noisy environment of a train car. Eight subjects adjusted the volume to an optimum level (L_(music)) in a simulated noisy train car environment. In Experiment Ⅰ, the effects of noise level (L_(train)) and type of train noise (rolling, squealing, impact, and resonance) were examined. Spectral and temporal characteristics were found to be different according to the train noise type. In Experiment Ⅱ, the effects of L_(train) and type of music (five vocal and five instrumental types) were examined. Each music type had a different pitch strength and spectral centroid, and each was evaluated by the amplitude of the first maximum peak (Φ_1) and the width of the first decay (W_(Φ(0)) of the autocorrelation function (ACF) of the music. Results showed that L_(music) increased as L_(train) increased in both experiments, while the type of music greatly influenced L_(music). The type of train noise, however, only slightly influenced L_(music). These results suggest that L_(music) can be estimated using L_(train) and the ACF factors Φ_1 and W_(Φ(0)).