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Norman, OK Noise Ordinances: Decibel Limits (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Residential night limit (L90)
50 dB(A), 9 p.m. to 7 a.m.
Residential day limit (L90)
55 dB(A), 7 a.m. to 9 p.m.
Industrial day limit (L90)
70 dB(A)
Tonal/cyclic sound
Limit reduced by 5 dB(A)
Measurement period
5 to 15 minutes per NCC 16-207

Summary

NCC 16-205 caps stationary noise sources by land-use district and time of day: residential limits run as low as 50 dB(A) at night and 55 dB(A) by day at the L90 ambient level, rising to 65-70 dB(A) commercial and 65-80 dB(A) industrial, with a 5 dB(A) stricter limit for tonal or pulsing noise.

Maximum permissible sound levels. It shall be a violation of this article for any person to operate or permit to be operated any stationary source of sound which either: Creates a sound level greater than 15dB(A) above the ambient sound level (L90) within any land use district during any measurement period; or Creates a 90th percentile sound level (L90), a tenth percentile sound level (L10) or a first percentile sound level (L1) for any measurement period which exceeds the limits set forth for the following receiving land use districts when measured at the boundary or at any point within the property affected by the noise. Residential 50dB(A) 55dB(A) 60dB(A) 65dB(A) 65dB(A) 70dB(A)

Full Breakdown

NCC 16-205 measures noise three ways at the property boundary or any point on the affected property: L90 (the level exceeded 90 percent of the time), L10, and L1. A stationary source violates the code if it either exceeds 15 dB(A) above the ambient L90 in any district, or exceeds the district's flat limits. ) and 55 dB(A) by day, with L10 and L1 ceilings of 60/65 dB(A) and 65/70 dB(A). Commercial districts run 55/60 dB(A) L90, and industrial districts run 65/70 dB(A) L90, up to 80/85 dB(A) L1.

Where a source's noise crosses land-use categories, the more restrictive district's limit governs at the boundary. 4-1971 Type II sound level meter under NCC 16-207. Section 16-205(b) tightens the standard further: any stationary source emitting a pure tone, cyclically varying, or repetitive impulsive sound has its table limit cut by 5 dB(A), and even a source that meets that reduced limit still violates the section if it creates a noise disturbance.

Violations & Fines

Violating NCC 16-205's limits is punishable under NCC 16-211 by a fine and/or imprisonment set by the City's penalty and fine schedule, with each violation or continued violation charged as a separate offense. NCC 16-212 additionally treats a breach of 16-205 through 16-210 as a nuisance subject to summary abatement by restraining order or injunction from a court of competent jurisdiction.

Frequently Asked Questions

What is the nighttime noise limit in a Norman residential zone?
NCC 16-205 caps stationary sources at 50 dB(A) L90 between 9 p.m. and 7 a.m. in residential districts, measured at the property boundary or any point on the affected property, using a 5-to-15-minute sampling period with a Type II sound level meter.
Are industrial noise limits higher than residential in Norman?
Yes. Industrial districts allow up to 70 dB(A) L90 by day and 65 dB(A) at night, compared to 55 dB(A) and 50 dB(A) in residential districts, with correspondingly higher L10 and L1 ceilings under NCC 16-205's table.
Does a humming or droning noise get a stricter limit in Norman?
Yes. NCC 16-205(b) cuts the applicable table limit by 5 dB(A) for any stationary source that emits a pure tone, cyclically varying, or repetitive impulsive sound, and it is still a separate violation if that source creates a noise disturbance even while meeting the reduced limit.

Sources & Official References

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