---
kind: "section"
citation: "49 C.F.R. § 325.23"
title: "49"
number: "325.23"
heading: "Type of measurement systems which may be used."
url: "https://uscodex.org/cfr/49/325.23"
---

# §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:

- (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](/cfr/49/3.2.md) of ANSI S1.4-1971.

## Notes

### Authority

Authority: 42 U.S.C. 4917; 49 U.S.C. 301; and 49 CFR 1.87.

### Source

Source: 40 FR 42437, Sept. 12, 1975, unless otherwise noted.