Section 20-2901. EQUIPMENT

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2901.1Sound-level meters and microphones shall meet Type II specifications per ANSI S1.4-1971.

2901.2Each sound-level meter shall be qualified annually.

2901.3Each 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).

                    
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