GB/T 16404.2-1999 Acoustics--Determination of sound power levels of noise sources using sound intensity--Part 2: Measurement by scanning (English Version)
General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest
GB/T 16404.2-1999
Scope
This standard specifies a method for measuring the sound intensity component perpendicular to the measuring surface, which should surround the noise source to be measured. The measurement surface is divided into several adjacent surface elements, and the area integral of the sound intensity perpendicular to the measurement surface is approximated by scanning the sound intensity probe on each surface element along a continuous path covering the surface element to a certain extent. The measuring instrument measures the average normal acoustic meridian component and the mean square sound pressure during each scan. Scanning can be performed with manual or mechanical systems. The weighted sound power level for a limited frequency band is calculated from the measured octave band or 1/3 octave band values. The method can be used for any sound source with a defined fixed measurement surface. On this measurement surface, as defined in 3.13, the noise generated by the measured sound source and other obvious external sound sources should be stable in time. The measurement surface is selected according to the size and shape of the sound source. The method can be used in field or special purpose test environments. This standard specifies auxiliary methods for judging accuracy levels, which are listed in Appendix B. If the accuracy of the results obtained by this method does not meet the requirements of this standard, the test process should be modified in the specified way. This standard does not apply to any frequency band where the measured sound power is negative. This standard can be applied to sound sources in any environment where changes in the environment over time do not degrade the accuracy of sound intensity measurements to an unacceptable level, or where sound intensity measurement probes do not encounter velocities that are Acceptable or unstable airflow (see 5.2.2, 5.3 and 5.4). This standard does not apply when the test conditions are so severe that the requirements of this standard cannot be met, such as when the external noise level may exceed the dynamic performance of the measuring instrument or change too much during the test period. Note 1: In this case other methods, such as the method specified in GB/T 16539 using surface vibration levels to determine sound power levels, may be more applicable.
GB/T 16404.2-1999 history
1999GB/T 16404.2-1999 Acoustics--Determination of sound power levels of noise sources using sound intensity--Part 2: Measurement by scanning