[Code of Federal Regulations] [Title 49, Volume 5] [Revised as of October 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR325.21] [Page 10] TITLE 49--TRANSPORTATION DEPARTMENT OF TRANSPORTATION PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS --Table of Contents Subpart C_Instrumentation Sec. 325.21 Scope of the rules in this subpart. The rules in this subpart specify criteria for sound level measurement systems which are used to make the sound level measurements specified in subpart D and subpart E of this part.