噪音减弱 meaning in Chinese

noise reduction
sound reduction

Road traffic noise reducing devices . test method for determining the acoustic performance . part 3 : normalized traffic noise spectrum
道路交通噪音减弱装置.声性能测试方法.第3部分:正常交通噪音范围
Road traffic noise reducing devices . test method for determining the acoustic performance . part 1 : intrinsic characteristics of sound absorption
道路交通噪音减弱装置.声性能测试方法.第1部分:声吸收的内在特性
Road traffic noise reducing devices . test method for determining the acoustic performance . part 2 : intrinsic characteristics of airborne sound insulation
道路交通噪音减弱装置.声性能测定试验方法.第2部分:气载声隔绝固有特性