Montgomery County, MD Noise from Specific Sources: Low-Frequency Bass Limits (2026)
Key Facts
- Low-frequency threshold
- 15 dB deviation at 125 Hz or below
- Standard-frequency threshold
- 5 dB deviation at 500 Hz+
- Tone noise cap
- 5 dBA below area's normal limit
- Enforcing agency
- Dept. of Environmental Protection
- Violation class
- Class A, up to $1,000 fine
Summary
Montgomery County sets a stricter decibel threshold for prominent discrete tones below 125 Hz, bass hums and whines, than for higher-frequency tones, and bars any such tone that exceeds 5 dBA under the area's normal noise limit.
Prominent discrete tone means a sound, often perceived as a whine or hum, that can be heard distinctly as a single pitch or a set of pitches. A prominent discrete tone exists if the one-third octave band sound pressure level in the band with the tone exceeds the arithmetic average of the sound pressure levels of the 2 contiguous one-third octave bands by: (1) 5 dB for center frequencies of 500 Hz and above; (2) 8 dB for center frequencies between 160 and 400 Hz; or (3) 15 dB for center frequencies less than or equal to 125 Hz.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-90: Montgomery County Code contains legislation effective through May 7, 2026 | Zoning Updated Effective: April 13, 2026 | COMCOR Regulations effective as of July 1, 2026).
Full Breakdown
The County's noise ordinance singles out low-frequency tonal noise, the kind of hum or whine a subwoofer, HVAC compressor, or heat pump produces, for tighter enforcement. Under County Code § 31B-2, a 'prominent discrete tone' exists when a one-third octave band's sound pressure exceeds the average of its two neighboring bands by 15 dB at center frequencies of 125 Hz or below, versus just 5 dB at 500 Hz and above, since low-frequency tones are harder to detect by ear but still disturbing. Section 31B-5(a)(2) then bars any prominent discrete tone that exceeds a level 5 dBA below the applicable area's standard daytime or nighttime noise limit. The Department of Environmental Protection enforces the chapter.
Violations & Fines
A prominent low-frequency tone above the 15 dB threshold is a Class A violation: up to $1,000 criminal fine and 6 months jail, or a $500 civil penalty ($750 for repeat offenses), enforced by DEP.
Frequently Asked Questions
Does Montgomery County treat bass noise differently from other sounds?
What noise level triggers a low-frequency tone violation?
Sources & Official References
Other rules in Montgomery County
Compare Montgomery County to another location·View the Maryland noise from specific sources overview
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