Study on prediction and evaluation of sound attenuation by various types of low-height noise barriers

摘要

Low-height noise barriers of about one meter in height placed along urban roads usually have open cuts because access control does not apply to them. In addition, by taking the surrounding landscape into consideration, the barriers may requirevarious designs and materials.The authors first define the two indices of sound reduction effects such as insertion loss (IL) and section-averaged insertion loss (SA·IL), and then propose the methods for calculating the effects by the following types of barriers: (1) theinfinite-length planter type which is considered as absorptive wide barrier; (2) the infinite-length panel type whose material has small transmission loss and (3) the type with open cuts added on (1) and (2). The calculation methods for the planter typeare verified by model experiments. Finally, the authors analyze the relationship between the sound reduction effects and the parameters for designing the low-height noise barriers such as evaluation section length, opening ratio, transmission loss of thematerial and so on.