ANSI S1.4: Scope and Relationship to IEC 61672-1
TL;DR
ANSI S1.4-2014 (R2024) is the US national standard for sound level meters, published by the Acoustical Society of America. It is substantially harmonized with IEC 61672-1 but retains the "Type" classification system (Type 0, Type 1, Type 2) rather than IEC "Class" designations. ANSI S1.4 is the standard referenced by US federal regulations including OSHA 1910.95, EPA noise guidelines, and many state and local noise ordinances. The current revision incorporates the technical requirements of IEC 61672-1:2013 while maintaining backward compatibility with older US regulatory language.
ANSI S1.4 vs IEC 61672-1
ANSI S1.4 and IEC 61672-1 are technically equivalent in most respects. The key differences are:
| Feature | ANSI S1.4 | IEC 61672-1 |
|---|---|---|
| Classification | Type 0, 1, 2 | Class 1, 2 |
| Type 0/— | Laboratory reference (no field equivalent) | Not defined |
| Type 1 / Class 1 | Precision measurements | Equivalent tolerances |
| Type 2 / Class 2 | General purpose | Equivalent tolerances |
| Regulatory reference | US (OSHA, EPA, HUD) | International (EU, ISO) |
Type 0 instruments are used exclusively in laboratories for calibrating other sound level meters. They have the tightest tolerances but are not designed for field measurements.
Scope of Application
ANSI S1.4 covers the same measurement quantities as IEC 61672-1:
- Time-weighted sound levels (LAF, LAS, LAI)
- Time-average levels (LAeq, SEL)
- Peak sound pressure level (LCpeak)
- A, C, and Z frequency weightings
- Fast, Slow, and Impulse time weightings
US Regulatory Context
ANSI S1.4 is specifically referenced by:
- OSHA 1910.95: Occupational noise exposure — requires Type 2 or better SLM
- EPA Noise Guidelines: Community noise assessment
- HUD Noise Policy: Residential site acceptability criteria
- FAA Part 150: Airport noise compatibility planning
- Numerous state and municipal noise codes
Amendment: ANSI S1.4A
ANSI S1.4A adds requirements for integrating-averaging sound level meters and specifies the Lavg (time-average level) computation used by OSHA dosimeters. This amendment bridged the gap between the original S1.4 (which covered conventional SLMs) and the integrating capabilities needed for occupational exposure assessment.
Choosing ANSI vs IEC
For measurements in the United States, ANSI S1.4 is the correct standard citation. For international work, cite IEC 61672-1. Since the technical requirements are equivalent, an instrument compliant with one generally meets the other. The SonaVyx SPL meter implements the common technical requirements shared by both standards. See Type classifications for detailed tolerance tables and calibration for US-specific verification requirements.
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Last updated: March 19, 2026