[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR325.31] [Page 756] TITLE 49--TRANSPORTATION CHAPTER III--FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 325--COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS--Table of Contents Subpart D--Measurement of Noise Emissions; Highway Operations Sec. 325.31 Scope of the rules in this subpart. The rules in this subpart specify conditions and procedures for measurement of the sound level generated by a motor vehicle engaged in a highway operation for the purpose of ascertaining whether the motor vehicle conforms to the Standards for Highway Operations set forth in 40 CFR 202.20.