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2015 Edition, 2015

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American National Standard Procedure for Measuring the Ambient Noise Level in a Room

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Product Details:

  • Revision: 2015 Edition, 2015
  • Published Date: January 2015
  • Status: Active, Most Current
  • Document Language: English
  • Published By: Acoustical Society of America (ASA)
  • Page Count: 38
  • ANSI Approved: Yes
  • DoD Adopted: No

Description / Abstract:

This standard specifies requirements and procedures for the measurement of sound pressure levels in building spaces or rooms. These requirements and procedures apply ideally to measurements performed in unoccupied spaces, with normal building services and HVAC equipment operating under relatively steady conditions. This standard, however, does not exclude measurements in occupied rooms. Transient noise sources, which for the purposes of this standard are defined as sounds with a duration of less than 10 seconds, are specifically excluded from this standard. This standard also does not apply to measurements made outdoors.

The requirements in this standard (identified by the use of the word shall) are to be understood as conditions on the measurements that must be met in order to state that such measurements have been made in conformance with this American National Standard. The guidelines and recommendations (identified by the use of the word should) are to be understood as conditions that will generally improve the accuracy, validity, applicability, documentation, and reporting of the measurement data but that are not mandatory for conformance. The type of sounds considered by this standard may differ widely in spectral characteristics. The sound to be measured may be essentially broadband or may contain discrete tones or narrow bands of noise. The frequency range covered by the requirements of this standard depends on the specific type of sound level meter or instrumentation being used, but, in general, the frequency content of the sound being measured should be contained within the range covered by the octave bands having center frequencies from 16 Hz to 8.0 kHz. The sound pressure levels of sounds whose energy is concentrated outside of this range may not be measured accurately according to the procedures of this standard.

This standard may be used to obtain one-third octave or octave-band sound pressure level spectra or single-number sound descriptors such as the time-average A-weighted overall sound level (also called the equivalent-continuous A-weighted sound pressure level). The standard may also be used to obtain the NC (noise criterion) level, the RC (room criterion) level, or other sound metric applicable to steadystate sounds which can be described by one-third octave bands.

To accommodate a wide range of applications, this standard provides two distinct measurement grades:

1) Survey method

• Provides a quick but only approximate noise evaluation.

• Generally adequate for an initial building commissioning process.

2) Engineering method

• Provides an accurate assessment of the noise level in a room.

• Generally sufficient to establish compliance relative to a noise criterion.

To avoid misinterpretation of noise test results obtained according to this standard, it is essential that the data be clearly marked as to whether they pertain to the survey or the engineering method. This is especially critical when the results are used to establish compliance to building design criteria. If the survey method fails to conclusively determine the compliance of a space with a given criterion, then the engineering method shall be used. Ideally, engineering method tests should be conducted withthe guidance of an experienced acoustical consultant, a professional engineer with appropriate sound level measurement experience, or a noise control engineer who has attained Board Certification through the Institute of Noise Control Engineering of the United States of America.


This standard has a number of purposes, all equally important. They are as follows:

1) To establish uniform procedures for measuring steady-state sound pressure levels in building spaces.

2) To facilitate the drafting of test codes, regulations, and the like by standardizing the basic requirements of sound pressure level measurements common to most of these documents. Rather than reiterating these requirements, the test codes and similar documents may simply refer to this document for the essential requirements.

3) To help make the procedures of acoustical measurements more accessible to regulatory personnel and the general public through clearly defining the steps and types of instrumentation necessary.