- Noise Basics
- Basics of Sound
- What models and metrics are used to measure Community Noise Exposure?
- What can I learn about Sound Perception and Hearing?
- What has been done to reduce Aircraft Noise?
- What are the Federal Aviation Regulations that deal with Aircraft Noise?
- How does Weather affect Aviation Operations?
In this section, you will learn about noise, including:
- The basics of sound
- Sound perception and hearing
In addition, you will learn about
- Efforts that have been undertaken to reduce noise
- Regulations from the Federal Aviation Administration aimed at reducing noise
- Regulatory guidance for planning for noise compatible land uses on and around airports
Finally, this section will discuss models and metrics used to measure noise and the impact of weather on aviation operations.
First and foremost, it is important to understand what is noise. This is discussed in the following section.
What is Noise?
Many variables influence people's perception of noise. However, since the level of annoyance changes from person to person, it is difficult to determine what is too noisy or annoying for an entire community. This extremely complex human response to noise makes noise impact assessment a challenging task.
METRICS and MODELS
Metrics are calculations that express the effect of noise. Models' are software programs that can be used to assess environmental impacts caused by many aspects of aircraft and their operations.
What is the primary noise metric used by the FAA?
To analyze the impacts of aviation noise, the Federal Aviation Administration (FAA) uses the Day-Night Average Sound Level (DNL) as the primary metric for quantifying individuals' cumulative exposure to aircraft noise.
Noise impact around airports can be described by computing other commonly used metrics. There are also supplemental metrics that provide additional information about noise from aircraft operations. The type of metrics used to measure noise depends on the community and their activity.
What is the primary set of models used by the FAA?
The FAA's Aviation Environmental Design Tool (AEDT) is a new software tool consisting of models to evaluate how noise and emissions affect each other. The AEDT combines existing noise and emissions models and provides insights into the interdependencies between noise, emissions, air quality and fuel consumption. This has use at local, regional, national and international levels. As an example, it could be used to assess the environmental benefits of changes to the air traffic management system. The latest version of AEDT is AEDT Version 2b service pack 2, released on December 22, 2015.
For more information on AEDT go to Models and Metrics
Commonly used metrics include:
- Maximum A-weighted Sound Levels (Lmax)
- Sound Exposure Level (SEL)
- Equivalent Sound Level (Leq)
- Time Above a Specified Sound Level (TA)
- Sound Pressure Level (SPL)
These metrics are computed in existing aircraft noise computer programs.
Another metric used in supplemental noise analysis is
Which supplemental noise metrics are often used?
- The most appropriate metric for a study varies. It depends on the purpose of the analysis, the audience, and several other factors.
- The most commonly used additional metric is the NA. This is because it asks the question, "How often will I hear airplanes and how loud will they be?"
- The TA and NA are often used to supplement the DNL metric. This is because the TA and NA break the DNL metric into its component parts. These metrics measure the number of times noise above a certain level is produced in a given time period (NA) and the total time you hear such noise in a given time period (TA).
The video links presented below help to illustrate some of these noise metrics.