Objective To observe the sound attenuation effect of several kinds of hearing protectors (earplugs and earmuffs) in an infrasound generator sound field.
目的观察几种护耳器 (耳塞、耳罩 )对次声发生器次声场的隔声效果。
In this article,ingeniously utilized tab gate and two times location system and overflow canal, and designed injection mold.
