Chapel Hill, NC Noise from Specific Sources: Low-Frequency Bass Limits (2026)
Key Facts
- Governing law
- Code of Ordinances § 11-39(a)(2), Table 2
- Frequency range
- 16 Hz to 630 Hz, 16 bands
- Residential daytime (16 Hz)
- 83 dB max
- Residential nighttime (16 Hz)
- 78 dB max
- Commercial/industrial bonus
- +5 to +10 dB over business limits
Summary
Chapel Hill's noise code has a second, frequency-specific limit aimed at bass-heavy sound that a standard decibel reading can understate. Table 2 sets one-third octave-band sound pressure limits for sixteen low frequencies from 16 Hz to 630 Hz at the property boundary, on top of the ordinary dBA cap.
(2)One-third octave-band sound pressure levels: Table 2. Maximum One-Third Octave-Band Sound Pressure Level Limitations At The Property Boundary—Plane by Primary Use Category, dB. One-Third Octave-Band Center Frequency, Hertz One-Third Octave-Band SPL, dB Residential Business, Office, Commercial, Institutional Daytime Nighttime Daytime Nighttime 16 83 78 98 88 20 75 70 90 80 25 67 62 82 72 31.5 60 55 75 65 40 57 52 72 62 50 56 51 71 61 63 55 50 70 60 80 54 49 69 59 100 53 48 68 58 125 52 47 67 57 160 51 46 66 56 200 50 45 65 55 250 49 44 64 54 315 47 42 62 52 400 45 40 60 50 500 43 38 58 48 630 41 36 56 46. ... (b)In Table 2, the allowed one-third (⅓) octave-band sound pressure levels for the nighttime and daytime for the shopping center, thoroughfare and industrial boundaries are +5 and +10 dB higher than is defined for the daytime business, office and commercial, and institutional boundary planes.
Full Breakdown
Chapel Hill's Noise Control Code has a second, frequency-specific standard aimed at bass-heavy sound that A-weighted dBA measurement can understate. Section 11-39(a)(2) sets Table 2, a one-third octave-band sound pressure level limit at the property boundary for sixteen center frequencies from 16 Hz up to 630 Hz, covering the low end where subwoofers, PA systems, HVAC equipment and idling engines carry the most energy. For residential property, the daytime limit falls from 83 dB at 16 Hz down to 41 dB at 630 Hz, and the nighttime limit is 5 dB lower at every frequency, for example 78 dB at 16 Hz falling to 36 dB at 630 Hz.
Business, office, commercial and institutional property gets a higher band: 98 dB daytime down to 56 dB at 630 Hz, and 88 dB nighttime down to 46 dB at 630 Hz. Section 11-39(b) sets the shopping center, thoroughfare and industrial band even higher, 5 dB above the business daytime figures and 10 dB above the business nighttime figures at every frequency in Table 2. A source violates the code if it exceeds either Table 1's A-weighted limit or any single Table 2 band limit, whichever standard the town measures against, under Sec.
11-39(a). When the noise source's property use differs from the receiving property's use, Sec. 11-39(c) applies the lower of the two categories' limits. The instrumentation and personnel training requirements of Sec. 11-38 govern how the town measures a Table 2 exceedance, including the requirement that sound-measuring equipment be at least a Type Two integrating-averaging meter.
Violations & Fines
Exceeding any one-third octave-band limit in Table 2 at the property boundary line, even if the A-weighted dBA reading in Table 1 looks compliant, is a violation of Sec. 11-39 enforced by the Chapel Hill Police Department; bass-heavy sources like car audio systems, subwoofers and mechanical equipment are the ones Table 2 is built to catch and cite.
Frequently Asked Questions
Does Chapel Hill regulate bass separately from regular noise?
What is Chapel Hill's low-frequency noise limit at a residence at night?
Do industrial properties get more room under Chapel Hill's bass noise table?
Sources & Official References
Other rules in Chapel Hill
Compare Chapel Hill to another location·View the North Carolina noise from specific sources overview
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