This map shows modeled outdoor noise across North Hill Historic District at 100-meter resolution, combining road, aviation, and rail sources. Green areas measure below 45 dBA. Orange and red exceed the EPA's 55 dBA outdoor threshold linked to long-term health effects. Use the layer toggles to view each source on its own or all together.
What the numbers sound like
- 30 dBAWhisper
- 40 dBASoft rainfall
- 45 dBAQuiet suburban street at night
- 50 dBAQuiet office
- 55 dBAEPA outdoor threshold: light traffic 100 ft away
- 60 dBANormal conversation an arm's length away
- 65 dBABusy restaurant
- 70 dBAHighway traffic 50 ft away
- 80 dBACity bus interior
Population Above the EPA Outdoor Threshold
The EPA's 55 dBA outdoor reference level is a common benchmark for residential noise exposure, especially for activity interference, annoyance, and long-term community noise concerns. About 1,679 North Hill Historic District residents, or 26.7%, live above that level. By land area, 34.0% of North Hill Historic District is above 55 dBA.
See how noise in North Hill Historic District compares to similar-sized neighborhoods.
Noise by Part of North Hill Historic District
Average noise levels for North Hill Historic District residents, grouped by direction from the center of North Hill Historic District. Eastern North Hill Historic District carries the highest population-weighted average; Central North Hill Historic District carries the lowest. Just 18% of residents in Central North Hill Historic District live in blocks above the EPA's 55 dBA threshold, about two-thirds of the share in Eastern North Hill Historic District.
Central North Hill Historic District
18% of people above 55 dBA
Eastern North Hill Historic District
36% of people above 55 dBA
Northern North Hill Historic District
24% of people above 55 dBA
Southern North Hill Historic District
31% of people above 55 dBA
Western North Hill Historic District
28% of people above 55 dBA
Eastern North Hill Historic District sounds about 25% louder than Central North Hill Historic District to the human ear, a 3.2 dBA gap. Every 10 dBA roughly doubles perceived loudness. Within any of these directions, two homes a quarter mile apart can still differ by 10 or more dBA depending on how close they sit to a major highway.
How far back from Highland Av do you need to be?
Highland Av produces an estimated 56 dBA at its loudest centerline points. Noise drops logarithmically with distance, with the exact rate depending on what's between you and the road. Tree cover, walls, terrain, and pavement type all matter. At roughly a quarter mile back, traffic fades into the noise level of a soft rainfall.
Calculated from the model's calibrated attenuation formula. About 31% of North Hill Historic District sits under tree canopy (heavier than most neighborhoods) and roughly 32% is impervious surface like pavement and rooftops. Both are folded into the per-place decay rate above. Heavier canopy pulls noise down faster with distance; impervious surfaces slow the drop.