Things to note when measuring and calibrating noise meters
1) Reference sound pressure level: 94dB.
2) Reference incident direction: axial direction of microphone
3) Microphone reference point: center of microphone diaphragm.
4) Correction data from sound pressure response to free field response (reference to incident direction).
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 tube equipped with the equivalent electrical impedance on the preamplifier.
6) Highest noise floor: When the sound level meter is placed in a low-level sound field and the microphone is replaced by the above-mentioned adapter and short-circuited, the highest possible local noise is 23dB (electrical noise level is 23dB).
7) Maximum sound pressure level allowed on the microphone: 145dB
8) Maximum peak input voltage of electrical input device: 10 Vp-p
9) The operating voltage range of the sound level meter when it meets the technical requirements: 4.8V~6V.
10) After the environmental conditions change, the typical time required to reach stability under reference environmental conditions is at least 12 hours, and at least 19 hours under other environmental conditions.
