Home / Standards / GB/T 4963-1985 GB/T 4963-1985 Abolished Normal equal-loudness contours for pure tones under free field listening conditions 自由场纯音标准等响线 Standard Type GBT ICS N/A CCS A42 Status 废止 Issue Date 1985-02-28 Implementation 1985-10-01 Responsible Dept 中国科学院 Drafting Unit N/A