What HUD's Noise Zones Actually Mean

A regulatory line, not a comfort scale

HUD's noise standard (24 CFR 51.104) sorts every site into three zones by day-night average sound level: Acceptable at 65 dB(A) or below, Normally Unacceptable from 65 to 75 dB(A), and Unacceptable above 75 dB(A). It exists to decide when federally assisted housing needs extra sound attenuation built in, not to describe how annoying a place feels.

What the middle zone actually requires

Inside Normally Unacceptable, HUD requires at least 5 dB of additional sound attenuation for sites reading 65 to 70 dB(A), and at least 10 dB for sites reading 70 to 75 dB(A). Above 75 dB(A), attenuation measures need approval from HUD's own Assistant Secretary for Community Planning and Development. Ladoga, IN reads well past that line, at 92 dB(A).

A second, related federal line

FHWA's own Noise Abatement Criteria (23 CFR 772, Table 1) sets a separate 66 dB(A) impact threshold for residential land use, close to but not identical to HUD's 65 dB(A) line. It's the number highway agencies use to decide whether a new road needs a sound wall, and it's noted on any place's page that clears it.

Two places that straddle the line

Chicago, IL sits in the band spanning HUD's 65 dB(A) acceptable line, and Baltimore, MD sits in the band spanning the 75 dB(A) unacceptable line. Neither page picks a single verdict for that boundary case; both report the honest range instead.

Where to go next

Real examples: Chicago, IL, Baltimore, MD, Ladoga, IN.

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