This map shows modeled outdoor noise across Great Brook Valley 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 1,073 Great Brook Valley residents, or 35.7%, live above that level. By land area, 39.4% of Great Brook Valley is above 55 dBA.
See how noise in Great Brook Valley compares to similar-sized neighborhoods.
Noise by Part of Great Brook Valley
Average noise levels for Great Brook Valley residents, grouped by direction from the center of Great Brook Valley. The highest population-weighted average is in southeastern Great Brook Valley; the lowest is in northern Great Brook Valley, where just 22% of residents live in blocks above the EPA's 55 dBA threshold, about half the share in the loudest section.
Southeastern Great Brook Valley
61% of people above 55 dBA
Central Great Brook Valley
25% of people above 55 dBA
Northern Great Brook Valley
22% of people above 55 dBA
To the human ear, noise in southeastern Great Brook Valley sounds about 66% louder than in northern Great Brook Valley, a 7.3 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 Noise Is Distributed Across Great Brook Valley
The bar chart below shows the share of Great Brook Valley residents in each noise band. About 87% of residents live below the EPA's 55 dBA threshold, and roughly 9% live in blocks above 60 dBA. Long-term exposure in that range is linked to elevated stress hormones and cardiovascular risk.
How Great Brook Valley Compares
Great Brook Valley sits the lowest among the peer group. Below: how Great Brook Valley's average outdoor noise and share of residents above the EPA threshold compare with Franklin Plantation, Bell Hill, Central Business District, and Indian Hill.
Average noise level (dBA)
Great Brook Valley's 53.3 dBA pop-weighted average is the lowest among the peer group. Massachusetts as a whole averages 54.3 dBA and the U.S. averages 52.0 dBA. Both are lower than Great Brook Valley because most of either area is rural land away from major roads.
Share of residents above 55 dBA
About 35.7% of Great Brook Valley residents live in blocks where outdoor levels exceed the EPA's 55 dBA threshold. That's fewer than any of its peer group. Measured by land area instead, 39.4% of Great Brook Valley's footprint sits above 55 dBA, against a Massachusetts average of 40.0% and a national average of 28.1%.
What This Means if You're Moving to Great Brook Valley
- 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 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 18% of Great Brook Valley is under tree cover (about average for neighborhoods), and the dominant land cover is medium-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.
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.