Response to low-frequency HVAC noise

Abstract

With the increasing use of variable air volume systems in building air-conditioning, there has been an increased occurrence of low-frequency and rumble noise problems. ASHRAE is currently funding a research program to determine the relationship between low-frequency HVAC noise and comfort in occupied spaces. A pilot psycho-acoustic study was conducted using up to nine subjects. Twelve noise stimuli representing various HVAC sounds were utilised and subjects assigned an annoyance and loudness rating using the absolute magnitude estimation technique. The results showed that for noise stimuli dominated by low-frequency energy, the annoyance was more severe than the loudness, rather than equal as has been generally assumed. The main study is currently underway and some of the results will be discussed. The subjective rating responses were correlated with the dB SPL and other noise metrics and Sound Quality metrics. The results have implications with respect to assessment of low-frequency noise in buildings and possibly to the external environment.