This map shows modeled outdoor noise across Julian 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 188 Julian residents, or 7.3%, live above that level. By land area, 10.7% of Julian is above 55 dBA.
See how noise in Julian compares to similar-sized cities.
Noise by Part of Julian
Average noise levels for Julian residents, grouped by direction from the center of Julian. Northern Julian carries the highest population-weighted average; Eastern Julian carries the lowest. Just 5% of residents in Eastern Julian live in blocks above the EPA's 55 dBA threshold, about two-thirds of the share in Northern Julian.
Eastern Julian
5% of people above 55 dBA
Northern Julian
10% of people above 55 dBA
Southern Julian
2% of people above 55 dBA
Western Julian
7% of people above 55 dBA
Northern Julian sounds about 57% louder than Eastern Julian to the human ear, a 6.5 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 do you need to be?
produces an estimated 65 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 20% of Julian sits under tree canopy (lighter than most cities) and roughly 6% 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.