2901. EQUIPMENT

2901 EQUIPMENT 2901.1 Sound-level meters and microphones shall meet Type II specifications per ANSI S1.4-1971. 2901.2 Each sound-level meter shall be qualified annually. 2901.3 Each sound-level meter and microphone device shall meet the following specifications: (a) External calibration devices with a known sound pressure level output at a single known frequency between two hundred (200) Hz and one thousand (1,000) Hz, as specified by the manufacturer; (b) Windscreen with insertion loss less than five tenths (0.5) dB(A) below eight (8) kHz; (c) Stopwatch, capable of cumulative operation and accurate to two percent (2%) or better; (d) Wind speed indicator with at least twenty percent (20%) accuracy at twelve miles per hour (12 mph); and (e) Earphones with impedance meeting the sound level meter manufacturer's specifications. SOURCE: Final Rulemaking published at 26 DCR 1499, 1501 (September 28, 1979).