A pilot study on acceptable sound levels for road traffic noise in urban parks

摘要

Intrusion of road traffic noise is one of the key issues to consider when designing soundscapes of urban parks. Several studies have discussed acceptable sound levels for road traffic noise in urban parks; however, almost all of them estimated acceptable sound levels from the dose-response relationship between sound levels and annoyance, or evaluation of acoustic comfort. Few studies have investigated acceptable sound levels directly. In this pilot study, psycho-acoustic experiments were conducted to assess acceptable sound levels for road traffic noise in an urban park directly. First, participants used semantic differential scales to evaluate soundscapes of five park videos recorded with a head and torso simulator. Then, the same five videos, each with six different added levels of road traffic noise, were presented in random order and participants were asked to evaluate whether the noise in each video was acceptable to them. The results show that a single level or a simple signal-to-noise ratio cannot explain acceptable levels. This conclusion suggests that guidelines or noise standards for urban parks should be established individually, depending on conditions and features of the respective parks. The effects of the evaluation of each park in relation to acceptable levels of road traffic noise are unclear in this study, and therefore further research is necessary.