{"data":{"id":"us/49-cfr-325.23","jurisdiction":"us","citation":"49 CFR 325.23","heading":"Type of measurement systems which may be used.","body":"The sound level measurement system must meet or exceed the requirements of American National Standard Specification for Sound Level Meters (ANSI S1.4-1971), approved April 27, 1971, issued by the American National Standards Institute, 1 throughout the applicable frequency range for either:\n(a) A Type 1 sound level meter;\n(b) A Type 2 sound level meter; or\n(c) A Type S sound level meter which has—\n(1) A weighing frequency response;\n(2) Fast dynamic characteristics of its indicating instrument; and\n(3) A relative response level tolerance consistent with those of either a Type 1 or Type 2 sound level meter, as specified in section 3.2 of ANSI S1.4-1971.","path":["Title 49—Transportation","Subtitle B—Other Regulations Relating to Transportation","CHAPTER III—FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER A—GENERAL REGULATIONS","PART 325—COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS","Subpart C—Instrumentation"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-49.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:34Z","sha256":"c909fb097eacba454074b3fffc06a01244711991dd4e6b03707f1146af5d79ac","source_id":"us-cfr","stale":true,"prev":"us/49-cfr-325.21","next":"us/49-cfr-325.25"},"notice":"GroundRules: Original legal text. Not legal advice."}