Although the equivalent continuous A-weighted sound pressure level (L Aeq) is widely used for environmental noise index, it is sometime not be sufficient to evaluate the perceived noisiness of road traffic noise, especially when it includes intermittent high-energy noise from the passing vehicles. In previous studies, the authors investigated the factors related to the specific noise and how they affect subjective impressions. However, few studies have focused on background noise. In this study, we examined how background noise levels and the degree of specific noise prominence influence perceived noisiness. To obtain the subjective evaluation in more realistic context, we conducted the experiment in a mock house to simulate living environment. The results showed that when the degree of specific noise prominence was high, the increase in noisiness caused by its presence remained consistent, regardless of background noise levels. However, when the degree was low, an increase in noisiness was observed only under high background noise conditions. Furthermore, when the degree was high, the perceived noisiness was lower than that of steady noise with an equivalent L Aeq. This might be caused by the positive effect of quiet background noise segments outweighed the negative impact of the specific noise events.
Kito et al. (Wed,) studied this question.