道磁性 meaning in Chinese

permeability

Cinematography - common to more than one film gauge - sound - specification for positions and width dimensions of recording and reproducing head gaps for three - , four - or six - track magnetic sound records on 35 mm and single - track on 17 . 5 mm motion - picture film containing no picture
电影技术.第5部分:多种胶片宽度的通用部分.第4节:伴音.第3小节:无图象的35mm和单轨17 . 5mm胶片上三四或六导道磁性声频记录用录音和放音头间隙的位置与宽度尺寸规范