GB/T 4129-2003
Acoustics-Requirements for the performance and calibration of reference sound sources used for the determination of sound power levels (English Version)

Standard No.

GB/T 4129-2003

Language

Chinese, Available in English version

Release Date

2003

Published By

General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China

Latest

GB/T 4129-2003

Replace

GB/T 4129-1995

Scope

This standard specifies the acoustic performance requirements for standard sound sources. -short-term stability and repeatability of sound power output; -spectral characteristics; To be determined by evaluating the radiation directivity pattern. Radiation pattern evaluation can only be performed in a semi-anechoic room environment due to directivity measurements (exception 5.5). For routine verification measurements, usually only frequency band sound power levels are determined. In this case, measurements can be performed under semi-anechoic or reverberant room conditions. This standard also specifies the sound source calibration method as a standard sound source, that is, under standard conditions (the characteristic impedance ρc of air is equal to 400 Pas/m), the standard sound source sound is represented by octave band and 1/3 octave band and A weighting. Calibration methods for power levels and specify different methods for radiation pattern evaluation and verification. NOTE: Standard sound sources can also be used for 1/2 octave band measurements, such as ISO 9295, but in this case the stability and reproducibility limitations described in this standard no longer apply. This standard not only specifies the calibration method of a standard sound source in a free field above a reflecting surface, but also specifies the calibration method of a standard sound source at different distances from the interface in a reverberation chamber. For the position of the standard sound source located on a reflective surface, the two different test environments mentioned above are considered equivalent in the frequency band greater than or equal to l00 Hz. Below 100 Hz, the measurement uncertainties of the two different test environments can be significantly different (see Table 1). This standard applies to standard sound sources. The sound source can be placed directly on the floor or mounted on a stand at a certain height from the floor. For sound sources placed on the floor, this standard only applies to sound sources whose maximum dimension in the height direction is less than 0.5 m and the maximum dimension in the horizontal direction is less than 0.8 m. According to this standard, only standard sound sources placed on the floor can be used for measurements at the measuring surface. For standard sound sources used or calibrated under reverberant room conditions, there is no maximum size limitation.

GB/T 4129-2003 history

• 2003 GB/T 4129-2003 Acoustics-Requirements for the performance and calibration of reference sound sources used for the determination of sound power levels
• 1995 GB/T 4129-1995 Acoustics--Determination of sound power levels of noise sources--Requirements for the performance and calibration of reference sound source