Prince William County, VA Noise from Specific Sources: Low-Frequency Bass Limits (2026)

Standard noise limits in County Code Sec. 14-4 are measured in A-weighted decibels, a scale that filters out low frequencies. Section 14-3 defines 'steady tonal sound' as sound 'characterized by a droning nature and which may be referred to as a whine, hum, rumble, or buzz,' naming heating, ventilating and air-conditioning units, refrigeration units, transformers, and backup generators as typical sources. Because A-weighting under-reports that content, Sec. 14-4(b) sets a separate, C-weighted cap for residential zoning districts: 73 dB(C) in the daytime and 68 dB(C) at night, measured at or within the residential property boundary, and the limit cannot be exceeded over any five-minute sampling interval.

The county's investigators use a Type 1 sound level meter set to C-weighting with slow response, taken at the receiving property line, and a single reading may run 3 dB over the cap, or 5 dB over if multiple sources are perceptibly beating against each other. Heating and cooling systems and radon mitigation systems serving a residence are exempt from the nighttime limits and from this subsection entirely. Anyone who cannot meet the limit, including a business running fixed mechanical equipment, may apply to the director of public works or the chief of police for a variance under Sec.

14-8, which is granted only if the sound does not endanger public health, safety or welfare, or if compliance would cause a hardship outweighing the public benefit.