ANSI S12-2 : 2008

1 Scope
2 Normative references
3 Terms, definitions, abbreviations, and symbols
4 Significance and use of this Standard and
  deviations from the previous ANSI S12.2-1995
5 Criteria
  5.1 A-weighted criteria
  5.2 NC (noise criteria) curves
  5.3 RNC (room noise criterion)
6 Acoustically induced vibrations and rattles
Annex A (informative) - Example evaluations using RNC
      A.1 Evaluation of room noise using the RNC curves
      A.2 Example 1 - Excessive turbulence
          (large standard deviation) and
          minimal surging
      A.3 Example 2 - Strong surging and
          strong turbulence
Annex B (informative) - A discussion of the criteria
      B.1 Discussion of RC, NC, and NCB
          criteria curves
      B.2 Discussion of RNC criteria curves
Annex C (informative) - Recommended noise level
                        criteria for various occupied
                        activity areas
      C.1 Recommended A-weighted criteria
      C.2 Recommended NC and RNC criteria
Annex D (informative) - RC Mark II
      D.1 Introduction
      D.2 Room criterion curves
      D.3 Spectrum classification
      D.4 Method for calculating an RC value
      D.5 Quality assessment index (QAI)
      D.6 Recommended criteria
Annex E (informative) - Criteria for recording
                        studios and other low-noise
                        situations
      E.1 Criteria
      E.2 Recording studio "audibility"
          threshold curves
Bibliography

Gives three primary methods for evaluating room noise: a survey method, an engineering method, and a method for evaluating low-frequency fluctuating noise.