Optimized discrete frequency qualification of reverberation rooms for AHRI Standard sound power testing of HVAC equipment

Evaluation of sound power levels of HVAC equipment using AHRI Standards may require the use of a qualified reverberation room to maintain a diffuse field, which is crucial for reproducibility and accuracy. AHRI Standard 220 prescribes the process to qualify a reverberation room, which involves qualifying the room at both broadband and discrete frequencies. Discrete frequency qualification is particularly tedious and time-consuming, requiring sequential sound measurements from a speaker emitting discrete frequency tones within each 1/3 octave band. This paper investigates the use of a random noise source (white/pink noise) as an alternative, analyzing the broadband FFT to extract the discrete frequency data required for qualification as per AHRI Standard 220. Additionally, results obtained from this alternative approach are compared with results obtained from traditional discrete frequency methodology used in AHRI Standard 220. This comparison is used to discuss faster alternatives when qualifying a reverberation room for tones.