Over the last decades, there has been an increase in the incidence of complaints of “rumble noise” due to the excessive acoustic energy below 250 Hz in HVAC systems. ASHRAE sponsored some research to first document the extent and degree of low frequency noise problems and, second, to determine by means of psycho-acoustic testing, a method of assessment of such noise. A secondary goal of the research was to determine, if possible, information that could be included in the ASHRAE handbook in terms of metrics and acceptable levels. This paper reports on some of the results obtained in this study with respect to assessment metrics and with respect to criteria and acceptable levels.

Units: Dual