Influence of Low SPL Frequency on Annoyance of Road Traffic Evaluation in Various Situation

Abstract

In this study, we investigated an influence of the frequency of low sound pressure level on the annoyance to road traffic noise when a natural sound was inserted in various level. Road traffic noise were recorded and edited to have the same equivalent continuous A-weighted sound pressure level (L_Aeq) but having different frequency of the low SPL. In addition, a natural sound such as bird twittering noise was added when the S/N ratio to the road noise was -25, -10 or 0 dB, respectively. Subjective annoyance evaluation tests were conducted and the result showed the road noise having more frequency of the low SPL was evaluated as softer even though both sounds had the same L_Aeq when the S/N ratio was large at -25 dB. However, the influence was not observed when the S/N ratio was smaller at -10 or 0 dB. From these results, the influence of low SPL frequency on the annoyance was found to vary depending on the inserted natural sound level.