[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR325.23]

[Page 794]
 
                        TITLE 49--TRANSPORTATION
 
                      DEPARTMENT OF TRANSPORTATION
 
PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS
--Table of Contents
 
                        Subpart C_Instrumentation
 
Sec. 325.23  Type of measurement systems which may be used.

    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:
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    \1\ Copies of the specification may be secured from the American 
National Standards Institute, 1430 Broadway, New York, New York, 10018.
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    (a) A Type 1 sound level meter;
    (b) A Type 2 sound level meter; or
    (c) A Type S sound level meter which has--
    (1) A weighing frequency response;
    (2) Fast dynamic characteristics of its indicating instrument; and
    (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.