Qualification Procedures for Reverberation Rooms

Qualification of reverberation rooms for HVAC equipment sound power metrics require measurements of the spatial and frequency uncertainty of the room. AHRI Standard 220 adopts the procedures of ANSI S12.51 and ISO 3741 for qualification, however some deviations exist that are intended to make AHRI 220 more restrictive. This paper provides an overview of three reverberation room qualification standards, outlining the major differences and evaluating the impact on an example room. AHRI Standard 220, AMCA Standard 300 and ISO 3741 are evaluated. During the example room testing, other deviations from the standards were evaluated in order to improve upon the qualification procedure and provide meaningful results. Most notably, the use of an anechoic source response vs. in-situ source response for discrete frequency qualification. Methods for meeting or improving discrete frequency uncertainty requirements are also discussed.