1. A. Sound Level Meter. A precision sound level meter meeting all the requirements of American National Standards Specification for Sound Level Meters ANSI S1.4—1971, or later revision, for a type 1 or a type S-1A instrument shall be used. The sound level meter shall be calibrated and certified annually with a method traceable to the U.S. National Bureau of Standards to verify its performance within design tolerances.

2. B. Acoustical Calibrator.

   1. (1) An acoustical calibrator of the microphone coupler-type shall be used for calibration of the sound level meter. The frequency of the calibration signal shall be 1000 Hz, ±5 percent.
   2. (2) The calibrator shall be adjusted and certified annually with a method traceable to the U.S. National Bureau of Standards to verify its correct performance within ±0.5 dB.

3. C. Microphone Windscreen.

   1. (1) A windscreen of the type recommended by noise meter manufacturers shall be used for all measurements to protect from wind noise. Installation of the windscreen may not cause a change in the sensitivity of more than ±.05 dB in the frequency range from 50 Hz to 5KHz or more then ±2 dB in the frequency range from 5 KHz.
   2. (2) It is sufficient that this compliance be demonstrated only at the annual system calibration and certification.
4. D. Anemometer. An anemometer, which has a steady-state accuracy within ±10 percent of any reading above 10 mpg (16 km/h), may be used to determine the wind velocity prevalent at the time of measurement.

Authority: Transportation Article, §§12-104(b), 22-601, 22-603, 22-605, 22-607, 22-608, 22-610, Annotated Code of Maryland

Effective date:

Regulations .01A, .02B, C, E, .03, and .04 adopted effective October 1, 1975 (2:22 Md. R. 1370)

Regulations .01B, .05—.08 adopted effective December 24, 1975 (2:29 Md. R. 1741)

Regulations .01C, .02, .09—.11 adopted effective October 1, 1975 (2:22 Md. R. 1371)

Regulations .07, .09, and .11 amended effective November 11, 1977 (4:24 Md. R. 1806)

Chapter revised effective April 9, 1984 (11:7 Md. R. 626)

Annotation: COMAR 11.14.05 cited in Attorney General Opinion No. 83-025 (June 15, 1983)

COMAR 11.14.05 Noise Abatement Program recodified to COMAR 11.14.07

Chapter revised effective April 17, 2000 (27:7 Md. R. 706)