[Code of Federal Regulations]
[Title 49, Volume 5]
[Revised as of October 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR325.9]

[Page 9]
 
                        TITLE 49--TRANSPORTATION
 
                      DEPARTMENT OF TRANSPORTATION
 
PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION 
STANDARDS--Table of Contents
 
                      Subpart A_General Provisions
 
Sec.  325.9  Measurement tolerances.

    (a) Measurement tolerances will be allowed to take into account the 
effects of the following factors:
    (1) The consensus standard practice of reporting filed sound level 
measurements to the nearest whole decibel.
    (2) Variations resulting from commercial instrument tolerances.
    (3) Variations resulting from the topography of the noise 
measurement site.
    (4) Variations resulting from atmospheric conditions such as wind, 
ambient temperature, and atmospheric pressure.
    (5) Variations resulting from reflected sound from small objects 
allowed within the test site.
    (6) The interpretation of the effects of the above cited factors by 
enforcement personnel.
    (b) Measurement tolerances shall not exceed 2 decibels for a given 
measurement.