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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.
Calibration Procedures
2.1 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 instrumentation involved shall have been carried out in a
laboratory 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
frequency. 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 known 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.
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