The noise-reducing effects of the cotton-yarn earplugs was evaluated by comparing the hearing threshold value of ear before and after the earplug wearing among 30 noise-free workers.

• 本文以非噪声作业青年30名为受试者,佩戴棉纱耳塞,用真耳阈值法作60耳的棉纱耳塞隔声值评价。