Standard No.:	GB/T 4854.7-1999
English Name:	Acoustics-Reference zero for the calibration of audiometric equipment-Part 7：Reference threshold of hearing under free-field and diffuse-field listening conditions
Chinese Name:	声学 校准测听设备的基准零级 第7部分：自由场与扩散场测听的基准听阈
Chinese Classification:	A42    Physics and Mechanics
Professional Classification:	GB    National Standard
ICS Classification:	17.140.01 17.140.01    Acoustic measurements and noise abatement in general 17.140.01
Source Content Issued by:	CSBTS
Issued on:	1999-03-08
Implemented on:	1999-9-1
Status:	superseded
Superseded by:	GB/T 4854.7-2008 Acoustics - Reference zero for the calibration of audiometric equipment - Part 7: Reference threshold of hearing under free-field and diffuse-field listening conditions
Superseded on:	2009-2-1
Target Language:	English
File Format:	PDF
Word Count:	6500 words
Translation Price(USD):	190.0
Delivery:	via email in 1~3 business day

本标准规定在下列使用条件下校准测听设备的基准听阈。A)听者不在时的声场由一自由平面行波(自由场)或一扩散场构成。若为自由平面行波，声源应在听者正前方(正入射)。B)若为自由场，声信号应为纯(正弦)音，若为扩散场，则应为1/3倍频带(白或粉红)噪声。C)声压级的测量应在听者不在时其头部的中心位置（两耳外耳道口联线的中点）。D)双耳收听。E)对应于基准听阈的声压级由一组人数合适的听者阈限的中数值确定。F)听者应为耳科正常人，年龄在18～25岁。G)听阈的确定用GB/T 16403规定的升降法或上升法。应予强调，阈限基准不同于GB 4854.1和GB/T 16402中规定的测听零级，因为后者属于用耳机的单耳测听，其声压级与规定的耦合腔和耳模拟器有关。因此，将本标准的基准和GB/T 4854.1或GB/T 16402中的基准作直接比较是不合适的。