Sound Power

In a specified frequency band, the rate at which acoustic energy is radiated from a source. In general, the rate of flow of sound energy, whether from a source, through an area, or into an absorber.

Sound power is not measured directly, but may be estimated in a number of ways from measurements of sound pressure or sound intensity. There a number of factors to consider when choosing the method of evaluating the sound power:

  1. The required accuracy
  2. The size and ease of transporting the machinery or equipment
  3. The test environment available for the measurements
  4. The background noise level
  5. The type of noise being measured
    • Impulsive
    • Broadband
    • Stationary
    • Non-stationary
    • Discrete frequency
  6. The instrumentation available for the measurements
  7. The type of sound power level required
    • Frequency weighted
    • Frequency bands
    • Frequency range
  8. Other acoustic information desired
    • Directivity
    • Temporal

Reference

ISO 3740:2000, Acoustics - Determination of sound power levels of noise sources - Guidelines for the use of basic standards.

ISO 3741:1999, Acoustics - Determination of sound power levels of noise sources - Precision methods for broad-band sources in reverberation room.

ISO 3743-1:1994, Acoustics - Determination of sound power levels of noise sources - Engineering methods for small, movable sources in reverberant fields - Part 1: Comparison method for hard-walled test rooms.

ISO 3743-2:1994, Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms.

ISO 3744:1994, Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering method in an essentially free field over a reflecting plane.

ISO 3745:1983, Acoustics - Determination of sound power levels of noise sources - Precision methods for anechoic and semi-anechoic rooms.

ISO 3746:1995, Acoustics - Determination of sound power levels of noise sources - Survey method.

ISO 3747:2000, Acoustics - Determination of sound power levels of noise sources - Survey method using a reference sound source.

ANSI S12.35 Precision Methods for the Determination of Sound Power Levels of Noise Sources in Anechoic and Hemi-Anechoic Rooms

ANSI S12.34 Determination of Sound Power Levels of Noise Sources for Essentially Free-Field Conditions over a Reflecting Plane

See also: Volume Velocity.

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