消音材料 meaning in English

acoustic material
acoustical coating
quieter material
sound-suppression material

Standard test method for measuring acoustical and airflow performance of duct liner materials and prefabricated silencers
测定导管衬里材料和预制消音材料的声及气流特性的标准试验方法
Sound wave passing through different mediums produces varied intensity diminution ; hence , greater sound muting materials can be utilized for noise reduction
音波透过不同介质，会产生不同的穿透损失，故利用特殊的消音材料，以达到消音效果。