scope:

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.