This map shows modeled outdoor noise across Southwest Ada 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 12,237 Southwest Ada residents, or 30.2%, live above that level. By land area, 35.0% of Southwest Ada is above 55 dBA.
See how noise in Southwest Ada compares to similar-sized neighborhoods.
Noise by Part of Southwest Ada
Average noise levels for Southwest Ada residents, grouped by direction from the center of Southwest Ada. Northern Southwest Ada carries the highest population-weighted average; Central Southwest Ada carries the lowest. Just 0% of residents in Central Southwest Ada live in blocks above the EPA's 55 dBA threshold, a fifth of the share in Northern Southwest Ada.
Central Southwest Ada
0% of people above 55 dBA
Eastern Southwest Ada
35% of people above 55 dBA
Northern Southwest Ada
34% of people above 55 dBA
Southern Southwest Ada
28% of people above 55 dBA
Western Southwest Ada
23% of people above 55 dBA
Northern Southwest Ada sounds about 117% louder than Central Southwest Ada to the human ear, a 11.2 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.
Loudest Road Corridors
The model evaluates every road in Southwest Ada using federal traffic counts, posted speeds, heavy-truck ratios, and pavement type. The source level shown is the modeled noise at the road centerline, where it is loudest. Noise drops with distance, faster in vegetated areas and slower over open pavement.
How far back from US Hwy 30 do you need to be?
US Hwy 30 produces an estimated 79 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 quiet suburban street at night.
Calculated from the model's calibrated attenuation formula. About 7% of Southwest Ada sits under tree canopy (lighter than most neighborhoods) and roughly 42% 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.
Airport Noise
Boise Air Trml/Gowen Field (BOI) sits east of Southwest Ada. The U.S. Department of Transportation models aviation noise around this airport from federal traffic data, and the model uses those federal measurements rather than synthetic predictions.
Blocks under the approach and departure paths carry combined road-plus-aviation noise, with some exceeding 55 dBA on the map's Overall layer. Blocks on the opposite side of Southwest Ada, particularly to the west, show no measurable aviation contribution. Use the Aviation toggle on the map above to isolate the airport's footprint.
How Noise Is Distributed Across Southwest Ada
The bar chart below shows the share of Southwest Ada residents in each noise band. About 75% of residents live below the EPA's 55 dBA threshold, and roughly 5% live in blocks above 60 dBA. Long-term exposure in that range is linked to elevated stress hormones and cardiovascular risk.
How Southwest Ada Compares
Southwest Ada sits at the quieter end of the spectrum. Below: how Southwest Ada's average outdoor noise and share of residents above the EPA threshold compare with Southeast Boise, West Valley, West Bench, and Vista.
Average noise level (dBA)
Southwest Ada's 52.5 dBA pop-weighted average is at the quieter end of the spectrum. Idaho as a whole averages 50.6 dBA and the U.S. averages 52.0 dBA. Both are lower than Southwest Ada because most of either area is rural land away from major roads.
Share of residents above 55 dBA
About 30.2% of Southwest Ada residents live in blocks where outdoor levels exceed the EPA's 55 dBA threshold. That's in the middle of its peer group. Measured by land area instead, 35.0% of Southwest Ada's footprint sits above 55 dBA, against a Idaho average of 17.7% and a national average of 28.1%.
What This Means if You're Moving to Southwest Ada
- Distance from highways matters more than the neighborhood name. Two homes in the same zip code can differ by 20 dBA if one sits 100 meters from US Hwy 30 and the other 500 meters away. The model captures this at 100-meter resolution, so noise exposure changes block by block.
- Tree canopy can help reduce modeled noise exposure. Roughly 7% of Southwest Ada is under tree cover (lighter than most neighborhoods), and the dominant land cover is low-intensity developed land. Both are measured from federal USDA Forest Service and USGS satellite imagery at 30-meter resolution. Streets with 60% or higher canopy show 3 to 5 dBA lower noise than comparable streets with bare ground or pavement, which is why the per-place decay rate above already accounts for it.
- Airport noise is directional. Boise Air Trml/Gowen Field's approach paths concentrate aviation noise to the east. Neighborhoods to the west of downtown show no measurable contribution from the airport.
Sources & Methodology
The BestNeighborhood noise model is calibrated against nearly one million federal ground-truth measurements across four states. Road noise is computed from segment-level federal traffic data and propagated outward using physics-based acoustic decay, with attenuation rates that depend on the surrounding land cover.
Federal datasets used:
FHWA Highway Performance Monitoring System: road geometry, traffic counts, lane configuration
U.S. DoT Bureau of Transportation Statistics National Transportation Noise Map: aviation and rail noise, road calibration ground truth
USGS / MRLC National Land Cover Database: land cover and impervious surface coverage
USDA Forest Service Tree Canopy Cover: vegetation density for sound propagation
U.S. Census Bureau TIGER/Line: block-level geography and population
U.S. EPA Levels Document: 55 dBA outdoor reference level
All inputs are published federal datasets. Block-level noise is computed by combining road, rail, and aviation sound sources in the energy domain, the same physics used in professional environmental noise assessments. Read the full methodology.