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ANNEX GENERAL CALIBRATION AND MEASUREMENT PROCEDURES
1.
Instrumentation
For the purpose of this Technical Memorandum sound level meters shall comply with International Electrotechnical Commission Publications 651 : 1980 (Type 1), and 804 : 1985 (Type 1), and other noise measuring and analysis instrumentation shall be of a comparable professional quality. Standard acoustical principles and practices shall be followed in the measurement and analysis of the noise under investigation.
2.
2.1
Calibration Procedures
Overall Calibration
To ensure measurement accuracy, within 12 months immediately
prior to taking any noise measurement or undertaking any noise analysis
for the purpose of this Technical Memorandum, overall calibration of the
involved shall have been carried out in a laboratory
instrumentation
suitably equipped for the purpose.
2.2 Field Calibration
Immediately prior to and following each noise measurement the accuracy of the sound level meter shall be checked using an acoustic calibrator generating a known sound pressure level at a known frequncy. Measurements may be accepted as valid only if the calibration levels from before and after the noise measurement agree to within 1.0 dB.
Where a tape recorder forms an integral part of the measuring system, a constant calibration signal corresponding to a known sound pressure level at a know frequency shall be applied at the beginning and end of each noise recording. A tape recording may be accepted as valid only if at the time of subsequent laboratory analysis the calibration levels from before and after the noise recording agree to within 1.0 dB.