part_subject: "NOISE EMISSION STANDARDS FOR TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS"
subpart_code: "C"
subpart_subject: "Measurement Criteria"
section_number: "201.22"
section_subject: "Measurement instrumentation."
cfr_reference: "40 CFR 201.22"
title_name: "Title 40"
title_subject: "Protection of Environment"
parts_covered: "Parts 190 to 259"
revised_date: "Revised as of July 1, 2019"
publication_date: "As of July 1, 2019"
contains_description: "Containing a codification of documents of general applicability and future effect"
publication_info: "Published by Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"
---
(a)A sound level meter or alternate sound level measurement system that meets, as a minimum, all the requirements of American National Standard S1.4-1971 1
for a Type 1 (or S1A) instrument must be used with the “fast” or “slow” meter response chacteristic as specified in Subpart B. To insure Type 1 response, the manufacturer's instructions regarding mounting or orienting of the microphone, and positioning of the observer must be observed. In the event that a Type 1 (or S1A) instrument is not available for determining non-compliance with this regulation, the measurements may be made with a Type 2 (or S2A), but with the measured levels reduced by the following amount to account for possible measurement instrument errors pertaining to specific measurements and sources:
1 American National Standards are available from the American National Standards Institute, Inc., 1430 Broadway, New York, NY 10018.
(b)A microphone windscreen and an acoustic calibrator of the coupler type must be used as recommended by: (1) the manufacturer of the sound level meter or (2) the manufacturer of the microphone. The choice of both devices must be based on ensuring that Type 1 or 2 performance, as appropriate, is maintained for frequencies below 10,000 Hz.