ECMA 74 8th-Edition2003好东西，分享

Standard
ECMA-74
8th Edition / December 2003
Measurement of Airborne Noise Emitted by Information Technology and Telecommunications Equipment


1 Scope 1
2 References 1
3 Terms and definitions 3
3.1 General definitions 3
3.1.1 basic noise emission standard (B-type standard) 3
3.1.2 noise test code (C-type standard) 3
3.1.3 information technology and telecommunications equipment 3
3.1.4 functional unit 3
3.1.5 work station 3
3.1.6 operating mode 3
3.1.7 idle mode 3
3.1.8 floor-standing equipment 3
3.1.9 table-top equipment 3
3.1.10 wall-mounted equipment 3
3.1.11 sub-assembly 4
3.1.12 rack-mounted equipment 4
3.1.13 standard test table 4
3.2 Acoustical definitions 4
3.2.1 sound pressure, p 4
3.2.2 time-averaged sound pressure level, LpT 4
3.2.3 emission sound pressure level, Lp 4
3.2.4 time-averaged emission sound pressure level, LpeqT 4
3.2.5 A-weighted impulse sound pressure level, LpAI 5
3.2.6 C-weighted peak emission sound pressure level, LpCpeak 5
3.2.7 sound power, W 5
3.2.8 reference sound source, 5
3.2.9 frequency range of interest 5
4 Conformance requirements 5
5 Installation and operating conditions 6
5.1 Equipment installation 6
5.1.1 General 6
5.1.2 Floor-standing equipment 6
5.1.3 Table-top equipment 6
5.1.4 Wall-mounted equipment 7
5.1.5 Rack-mounted equipment 7
5.1.6 Hand-held equipment 7
5.1.7 Sub-assemblies 7 - i -
5.2 Input voltage and frequency 7
5.3 Equipment operation 7
6 Method for determining sound power levels of equipment in reverberation rooms 8
6.1 General 8
6.2 Measurement uncertainty 8
6.3 Test environment 9
6.3.1 General 9
6.3.2 Meteorological conditions 9
6.4 Instrumentation 10
6.4.1 General 10
6.4.2 The microphone and its associated cable 10
6.4.3 Frequency response of the instrumentation system 10
6.4.4 Reference sound source 10
6.4.5 Filter characteristics 10
6.4.6 Calibration 10
6.5 Installation and operation of equipment: General requirements 10
6.6 Microphone positions and source locations 10
6.6.1 General 10
6.6.2 Number of microphone positions, reference source locations and equipment locations 11
6.6.3 Microphone arrangement 11
6.7 Measurement of sound pressure level 11
6.7.1 General 11
6.7.2 Measurement duration 11
6.7.3 Corrections for background noise 11
6.8 Measurement of the sound pressure level of the reference sound source 11
6.9 Calculation of space/time-averaged band sound pressure level 11
6.10 Calculation of sound power level 11
6.10.1 Calculation of band sound power levels 11
6.10.2 Calculation of A-weighted sound power level 11
7 Method for determining sound power levels of equipment under essentially free-field conditions over a reflecting plane 14
7.1 General 14
7.2 Measurement uncertainty 14
7.3 Test environment 15
7.3.1 General 15
7.3.2 Meteorological conditions 15
7.4 Instrumentation 15
7.4.1 Microphone and its associated cable 15
7.4.2 Calibration 15
7.5 Installation and operation of equipment: General requirements 16 - ii -
7.6 Measurement surface and microphone positions 16
7.6.1 General 16
7.6.2 Microphone positions on the measurement surface 17
7.7 Measurement of sound pressure levels 17
7.7.1 General 17
7.7.2 Measurement duration 17
7.8 Calculation of surface sound pressure level and sound power level 18
8 Method for measuring emission sound pressure levels at defined operator and bystander positions 18
8.1 General 18
8.2 Measurement uncertainty 18
8.3 Test environment 19
8.3.1 General 19
8.3.2 Meteorological conditions 19
8.4 Instrumentation 19
8.5 Installation and operation of equipment 19
8.6 Microphone positions 19
8.6.1 At the operator position(s) 19
8.6.2 At the bystander positions 20
8.6.3 Microphone orientation 20
8.7 Measurement of sound pressure levels 21
8.7.1 General 21
8.7.2 Measurement duration 22
8.7.3 Calculation of A-weighted emission sound pressure levels from band levels 22
8.8 Calculation of the mean emission sound pressure level at the bystander positions 22
9 Information to be recorded and reported 23
9.1 Information to be recorded 23
9.1.1 Equipment under test 23
9.1.2 Acoustical environment 23
9.1.3 Instrumentation 24
9.1.4 Acoustical data 24
9.2 Test report 26
Annex A - Test accessories 29
Annex B - Measurement surfaces 33
Annex C - Installation and operating conditions for specific equipment categories 37
- iii -
Annex D - Identification and evaluation of prominent discrete tones 67
Annex E - Detection of impulsive sound pressure levels 79
Annex F - Bibliography 81