The measurement of noise or sound shall be made with a sound level meter meeting the standards prescribed by the American National Standards Institute. The instruments shall be maintained in calibration and good working order. A calibration check shall be made of the system at the time of any noise measurement. Measurements recorded shall be taken so as to provide a proper representation of the noise source. The microphone shall be positioned so as not to create an unnatural enhancement or diminution of the measured noise. A windscreen for the microphone shall be used when required. The measurement shall be an “A” weighted, slow response sound level.