This standard applies to HVAC products where sound power is
determined by measurement using the Comparison Method in a
reverberation room that meets the qualification requirements as
defined in Section 4 of this standard.
Purpose. The purpose of this standard is to provide the
methodology for the determination of Sound Power Levels of noise
sources that emit Broadband Sound and/or Discrete Frequency
Sounds/Tones in reverberation rooms. The method described herein
requires reverberation room pre-qualification through test and the
use of the Comparison Method to determine Sound Power Levels. This
standard specifies the physical environment, procedures, and
equipment used to qualify the reverberation room by test.
Pre-qualifying the room ensures adequate modal density with the use
of one source locations to obtain acceptable accuracy and
repeatability of results. The Reference Sound Source (RSS) used for
the Comparison Method relies on ANSI/AHRI Standard 250 to
accurately calibrate the RSS at all frequencies of interest. Sound
rating values are often useful for applications and design,
therefore it is important to acquire data and qualify measurement
rooms in Onethird Octave Bands. The use of the Comparison Method
reduces a number of potential sources of error. The standard
contains information on instrumentation, installation and operation
of the source, procedures for determining the number of microphone
positions or length of traverse, and procedures for the calculation
of Sound Power Level. Measurements made in conformity with this
standard will, with very few exceptions, result in standard
deviations equal to or less than specified in Table 1.
The frequencies covered in this standard range from the 50 Hz to
the 10,000 Hz One-third Octave Band (63 Hz to 8000 Hz Octave
Bands). The 50 to 80 Hz one-third octave band sound for HVAC
equipment affects product applications and often cannot be ignored.
The product specific AHRI standard will specify the frequency range
of interest for qualification, calculation, and reporting. This
standard is based on ANSI S12.51/ISO 3741 but provides additional
exceptions and extensions.
Intent. This standard is intended for the guidance of
the industry, including manufacturers, engineers, installers,
contractors and users.
Review and Amendment. This standard is subject to
review and amendment as technology advances.
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