§FMCSR.com
Current textIn force on Sept. 30, 2002Source: annual CFR editions 1996–2016

§ 325.9 Measurement tolerances.

Current wording, first on file in the 1996 annual edition.

govinfo, 2001 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2001 edition's wording. An amendment that took effect between Oct. 1, 2001 and Sept. 30, 2002 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 325.9 — Measurement tolerances.. Text in force on September 30, 2002. This wording effective October 1, 1996 to present. Source: govinfo, 2001 edition, https://www.govinfo.gov/app/details/CFR-2001-title49-vol4/CFR-2001-title49-vol4-sec325-9. Retrieved from FMCSR.com, https://fmcsr.com/reg/325.9?asof=2002-09-30, on October 26, 2026. Unofficial compilation; verify against the official source.

(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.

Amendment history

1 distinct wording on file since Oct. 1, 1996
  1. Oct. 1, 1996 → presentannual editions 1996–2016viewing

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.