Dearborn, MI Noise Ordinances: Decibel Limits (2026)

Table A sets three zoning-district ceilings, each split by time of day. , and 50 dB(A) overnight. Commercial lots allow 65 dB(A) daytime and 60 dB(A) overnight. Industrial lots surrounded entirely by other industrial-zoned property may run 70 dB(A) around the clock, dropping to 60 dB(A) if any adjacent parcel carries a different zoning. Measurements are taken at the lot's boundary line with an ANSI-calibrated, A-weighted sound meter. A companion duration chart forgives short spikes: a source running up to 30 minutes per hour gets a +3 dB(A) allowance, down to +15 dB(A) for bursts of two minutes or less per hour.

Where preexisting street traffic or lawful background noise already exceeds Table A, a use may match that ambient level rather than the table figure, as determined by the zoning administrator. Intermittent or pure-tone sounds that stay under the numeric limit but still draw complaints trigger a zoning administrator investigation, and unresolved, justified complaints after 60 days become enforceable under the zoning ordinance's general remedies. A property owner who cannot meet the table may apply to the Board of Appeals for a variance, supported by a background-noise study and a projected boundary-line noise level; the board may grant relief only where strict compliance creates unnecessary hardship without threatening public health or safety, and may attach operating conditions. m.