Aircraft Noise Statistics

...Loading...

Select statistic to plot:
Select type of aircraft:
Select time period:

Available Statistics

Number of noise events per week (or per day)

The number of noise events per week (or per day) is the total number of noise events recorded in the selected time period for the selected aircraft type, divided by the number of weeks (or days) in the period. A noise event is a detected rise in the (A-weighted) decibel level associated with an individual aircraft passing overhead or operating on the ground at the airport. (Note that fighter jet noise events often involve multiple formation aircraft.) To qualify as a noise event here, the peak decibel level (see below) for the event must exceed 65dBA (55dBA at night), and rise at least 10dB above the ambient background noise level from traffic and other sources before and after the event.

Minutes/Seconds of noise per week (or per day)

The total minutes of noise per week (or per day) is the sum of the durations of all aircraft noise events recorded in the selected time period for the selected aircraft type, divided by the number of weeks (or days) in the period. Minutes (or seconds) of noise per week at 70/80/90/100+ dBA is calculated similarly, but restricted to time when the decibel level during the event was at or above the associated decibel threshold.

Peak decibel level (L_max)

Peak decibel level is the maximum one-second dBA reading for an individual noise event. Available statistics include the maximum peak decibel level recorded among all noise events in the selected time period for the selected aircraft type, along with various percentiles. For example, the 75th percentile of L_max means that 75 percent of noise events in the time period had an L_max level below the shown value and 25 percent had an L_max at or above the value.

Peak loudness

Peak "loudness" is another way to measure the peak noise level produced during a noise event. Peak loudness compares the peak decibel level of the event to the decibel level from ambient background noise before and after the event, and applies a general rule of thumb that perceived loudness doubles every 10 decibels. A noise event with a peak decibel level of 100dBA at a time when the ambient background noise is 50dBA will thus have a peak loudness of 2⁵ = 32 times louder than the background noise level.

Equivalent continuous sound level (L_eq)

Equivalent continuous sound level is a measure of the average acoustic energy over a period of time. Acoustic energy is the magnitude of the fluctuations in air-pressure due to sound over time: each 10dB increase in sound level corresponds to a tenfold increase in acoustic energy. L_eq is the constant sound level that would contain the same acoustic energy as all of the noise events in the selected time period.

Day-Night average sound level (DNL)

Day-night average sound level is similar to L_eq, except that nighttime noise (between 10PM and 7AM) is given an artificial 10dB penalty (meaning 10 times the acoustic energy) to account for people's greater sensitivity to nighttime noise.

Loudness-Minutes per week

Loudness-minutes is another metric to account for both the magnitude and duration of noise. Loudness-minutes are calculated by summing the second-by-second loudness level (see Peak loudness above) of all noise events in the selected time period for the selected aircraft type, converting to minutes, and dividing by the number of weeks in the period. Thus one minute at a loudness level of 5 times ambient background equals 5 loudness-minutes.

Data recovery

The percent of the selected time period with data from the noise meter. If the meter was not deployed for the entire period, it is the percent of the in-service period with data. (The in-service period for each meter can be found by clicking on the meter icon on the map.)

Aircraft Types

Military fighter jets

Military fighter jets include the current F-35A and prior F-16C fighters deployed by the local 115th Fighter Wing of the Wisconsin Air National Guard, as well as occasional itinerant fighter jets such as T-38 and F-18 fighters that are based elsewhere.

Large jets

Large jet aircraft are defined here as turbo-fan powered aircraft with a maximum gross takeoff weight of at 20,000 pounds or more. This category includes commercial airliners serving the Dane County Regional Airport, as well as some larger general-aviation jets.

Small jets

Small jet aircraft include turbo-fan powered aircraft with a maximum gross takeoff weight of less than 20,000 pounds. These include business jets as well as some smaller commercial aircraft serving the DCRA.

Large propellor-driven aircraft

Large propellor-driven aircraft include propellor aircraft with a maximum gross takeoff weight of at least 12,500 pounds or having seating for 15 or more people. This category includes prop-driven commercial aircraft, some larger general-aviation aircraft and occasional itinerant military aircraft.

Small propellor-driven aircraft

Small propellor-driven aircraft include single-engine and twin-engine propellor aircraft with a maximum gross takeoff weight of 12,500 pounds or less and fewer than 15 seats. These are almost entirely general-aviation aircraft.

Helicopters

Helicopters are rotary-wing aircraft, including civilian Med Flight helicopters operating in the Madison area, as well as fleet of UH-60 Blackhawk helicopters deployed by the locally-based Wisconsin Army National Guard's 1st Battalion, 147th Aviation Regiment.

UW hospital Med Flight — UW Hospital Med Flight

Other/Unknown

These are uncommon aircraft types such as ultralights or aircraft that are not readily identified from ADS-B data.

Download all summary statistics as CSV
(Download data description)