The earphones for air conduction and bone conduction testing were TDH-39P and Radioear B-71 models, which accorded with GB/T 4851.1 and GB/T 485 4.3 criteria after adjustment. The impedances of electrode were all less than 5 k ?

• 气、骨导测试所用耳机分别为TDH-39P和RadioearB-71；经校准；符合GB/T4854.；1与GB/T4854