GB/T 6881.1-2002 in English

本标准规定了应用具有规定声学特性的混响测试室，来确定作为频率函数的声源辐射声功率的实验室方法。基本标准系列的其他文件提出了不同的环境要求，具有那些特性的房间不适用于本标准。

Scope

1.1 This standard stipulates that when the sound source operates under the standard weather conditions corresponding to the characteristic negative reactance ρс=400 N s/m (upper 3) (ρ is the air density, с is the speed of sound), the sound power generated by it is measured. Direct method and comparative method, which specifies the requirements of the test room, the location of the sound source and the rules of the general operating conditions, the instruments and techniques for carrying out the square mean sound pressure level measurement, so as to calculate the octave frequency range of the sound source with class 1 accuracy or 1/3 octave sound power level. The quantity to be measured is the time-averaged band sound pressure level and the quantities to be determined are the A-weighting and band sound power level. Other quantities that may be chosen are other frequency-weighted sound power levels calculated from frequency band measurements. This standard does not provide methods for determining the directivity and transients of sound sources. Usually the frequency range to be considered is 1/3 octave of the center frequency from 100 Hz to 10000 Hz. Appendix C gives guidelines for the use of specified methods for extending the frequency range to lower frequencies. This standard does not apply to 1/3 octave bands in the frequency range higher than 10000 Hz. For high frequencies, the method of ISO 9295 is recommended. 1.2 The method specified in this standard is applicable to the steady-state noise described by ISO 12001 with respect to broadband, narrowband and discrete frequency components. Noise can be generated by machines, components, devices and accessories. This standard applies to sources whose volume is at least not greater than 2% of the volume of the reverberation chamber used for testing, and whose volume is greater than 2% of the volume of the room, and may exceed the standard deviation given in Table 2.