This map shows modeled outdoor noise across Napili-Honokowai 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 2,648 Napili-Honokowai residents, or 34.5%, live above that level. By land area, 29.3% of Napili-Honokowai is above 55 dBA.
See how noise in Napili-Honokowai compares to similar-sized neighborhoods.
Noise by Part of Napili-Honokowai
Average noise levels for Napili-Honokowai residents, grouped by direction from the center of Napili-Honokowai. The highest population-weighted average is in central Napili-Honokowai; the lowest is in northern Napili-Honokowai, where just 2% of residents live in blocks above the EPA's 55 dBA threshold, a fifth of the share in the loudest section.
Central Napili-Honokowai
30% of people above 55 dBA
Northeastern Napili-Honokowai
22% of people above 55 dBA
Southwestern Napili-Honokowai
2% of people above 55 dBA
Northern Napili-Honokowai
2% of people above 55 dBA
To the human ear, noise in central Napili-Honokowai sounds about 162% louder than in northern Napili-Honokowai, a 13.9 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.
Airport Noise
Kahului (OGG) sits east of Napili-Honokowai. 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 60 dBA on the map's Overall layer. Blocks on the opposite side of Napili-Honokowai, 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 Napili-Honokowai
The bar chart below shows the share of Napili-Honokowai residents in each noise band. About 28% of residents live below the EPA's 55 dBA threshold, and roughly 0% live in blocks above 60 dBA. Long-term exposure in that range is linked to elevated stress hormones and cardiovascular risk.
How Napili-Honokowai Compares
Napili-Honokowai sits the highest among the peer group. Below: how Napili-Honokowai's average outdoor noise and share of residents above the EPA threshold compare with Pukalani, Wailea, kaanapali-lahaina-hi, and waihee-wailuku-hi.
Average noise level (dBA)
Napili-Honokowai's 54.5 dBA pop-weighted average is the highest among the peer group. Hawaii as a whole averages 54.8 dBA and the U.S. averages 52.0 dBA. Both are lower than Napili-Honokowai because most of either area is rural land away from major roads.
Share of residents above 55 dBA
About 34.5% of Napili-Honokowai residents live in blocks where outdoor levels exceed the EPA's 55 dBA threshold. That's more than any of its peer group. Measured by land area instead, 29.3% of Napili-Honokowai's footprint sits above 55 dBA, against a Hawaii average of 34.4% and a national average of 28.1%.
What This Means if You're Moving to Napili-Honokowai
- 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 Honoapiilani Hwy 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 0% of Napili-Honokowai is under tree cover (about average for neighborhoods), and the dominant land cover is . 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. Kahului'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.