Issues with noise meter calibration and measurement that need to be addressed
1) Reference sound pressure level: 94dB .
2) Reference direction of incidence: axial direction of the microphone
3) Microphone reference point: the center of the microphone diaphragm.
4) Correction data from sound pressure response to free field response (referenced to the direction of incidence).
Frequency (Hz) 1k 1.25k 1.6k 2k 2.5k 3.15k
Correction value dB 0.2 0.3 0.4 0.5 0.6 0.8
Frequency (Hz) 4k 5k 6.3k 8k 10k 12.5
Correction value dB 0.2 0.3 0.4 0.5 4.5 6.2
5) Electrical input equipment: The equivalent electrical impedance can be used instead of the microphone for electrical signal testing. The capacitance of the equivalent electrical impedance is 20pF, and the insulation resistance is greater than 1GΩ. When using, screw the shielding cylinder equipped with the equivalent electrical impedance on the preamplifier.
6) The highest background noise: When the sound level meter is placed in a low sound level sound field and the microphone is replaced by the above adapter and short-circuited, the highest possible local noise is 23dB (the electrical noise level is 23dB).
7) The maximum sound pressure level allowed on the microphone: 145dB
8) Maximum peak input voltage for electrical input devices: 10 Vp-p
9) The operating voltage range when the sound level meter meets the technical requirements: 4.8V~6V.
10) After the environmental conditions change, the typical time required to achieve stability under the reference environmental conditions is at least 12 hours, and at least 19 hours under other environmental conditions.
