POL Government Elected Officials Auditor Mary Hull Caballero Charter, Code and Policies City Code & Charter Online Code & Charter Title 18 Chapter 18.04  Standards And Definitions
18.04.020 Measurement of Sound.

(Amended by Ordinance Nos. 159276 and 175772, effective August 1, 2001.) 

A. If measurements are made with a sound level meter, the meter shall be an instrument in good operating condition, meeting the requirements of a Type I or Type II meter, as specified by ANSI Standard 1.4‑1971.  For purposes of this Title, a sound level meter shall contain at least an A‑weighted scale, and both fast and slow meter response capacity.
B. If measurements are made with other instruments, the procedure shall be carried out in such a manner that the overall accuracy shall be at least that called for ANSI standard 1.4‑1971 for Type II instruments.
C. When the location or distance prescribed in this Title for measurement of sound is impractical or would provide misleading or inaccurate results, measurements may be taken at other locations or distances using appropriate correction factors specified in this Title or in other rules promulgated by the Noise Control Officer.
D. Procedures and tests required by this Title and not specified herein, shall be placed on file with the City Auditor.
E. For purposes of determining compliance with the measurable sound level requirements found in the Portland City Code, approved sound level meters shall utilize a Fast meter response setting. Slow sound level meter settings shall not be used for the purpose of determining compliance with the Portland City Code, unless directed by the Noise Control Officer.