Anechoic coatings with single cylindrical cavities are used traditionally whose effective frequency band is very narrow 传统的消声层使用单一圆柱腔谐振吸声,但是吸声频带很窄。
2.
Amendment 1 - transmission of audio and or video and related signals using infra - red radiation - part 2 : transmission systems for audio wide band and related signals 采用红外辐射的音频和或视频及相关信号的传输.第2部分:声频带和有关信号用传输系统.修改件1