Resources

Acoustics - The science of sound, including its production, transmission, reception, and effects

ADO - Airports District Office (FAA)

AIP - Federal Airport Improvement Program, provides federal grants to airports for the purposes of airport planning, airport development, or noise compatibility projects. Funded entirely from aviation fees, taxes, and charges.

Ambient noise - The all-encompassing sound associated with a given environment at a specified time, being usually a composite of sound from many sources at many directions, near and far; no particular sound is dominant.

Amplitude - The maximum value of a quantity.

ANCA - Airport Noise and Capacity Act of 1990, prohibits U.S. airports from adopting overly restrictive or outright punitive anti-noise ordinances.

ANOMS - Airport Noise and Operations Monitoring System, collects aircraft flight track data and noise event information for the analysis of flight patterns and the resulting noise impacts.

ANSP - Aviation Noise and Satellite Programs Office (MAC)

ASNA - Aviation Safety and Noise Abatement Act of 1979, principle law supporting federal efforts to identify and reduce noise and non-compatible land uses around civil airports in the U.S.

ATC, ATCT - Air Traffic Control, Air Traffic Control Tower (FAA), are responsible for the safe and efficient expedition of aircraft through the National Airspace System.

ATNS - Air Traffic Noise Screening, noise model used by the FAA to help air traffic planners determine whether certain air traffic actions involving aircraft flying above 3,000 feet are likely to cause adverse community reactions.

A-weighted sound level - The sound level obtained by the use of A- weighting. Unit: decibel, Unit symbol: dBA; A-weighting significantly de-emphasizes noise at low and high frequencies and is most commonly used when evaluating environmental noise.

Bel - A unit of level of which denotes the ratio between two quantities proportional to power; the number of bels corresponding to this ratio is the logarithm to the base 10 of this ratio (1 bel = 10 decibels).

CEE - Center for Energy and Environment, manages the Part 150 Residential Sound Insulation Program for the MAC.

CFR - Code of Federal Regulations

CIP - Capital Improvement Program, airport development and construction programs that will benefit the airport and the National Airspace System.

Close-In Noise Abatement Departure Profile - unique departure profile (NADP) designed to minimize noise impact for communities within the immediate vicinity of the runway end (within 3.5 miles from the start of takeoff roll).

C-weighted sound level - The sound level obtained by the use of C-weighting. Unit: decibel, Unit symbol: dBC; C-weighting is nearly flat throughout the audible frequency range, is preferable in evaluating sounds whose low-frequency components are responsible for secondary effects such as shaking or rattling of a building.

Decibel - logarithmic quantities or the ratio of two pressures, the numerator being the pressure of the sound source of interest, and the denominator being the reference pressure (the quietest sound we can hear.)

DGPS - Differential Global Positioning System

Distant Noise Abatement Departure Profile - unique departure profile designed to minimize noise impact for communities that are not within the immediate vicinity of the runway end (beyond 3.5 miles from the start of takeoff roll).

DME - Distance Measure Equipment

DNL - Day-night average sound level, used to describe the cumulative or total noise exposure during an average annual day. DNL is an energy average noise level over a 24-hour period, with a 10dB penalty for operations occurring between 10 p.m. and 7 a.m.

DOD - Department of Defense

DOT - Department of Transportation

EA - Environmental Assessment, used to determine whether or not proposed airport projects will have one or more significant impacts.

EIS - Environmental Impact Statement, required if a proposed project will have a significant impact. The EIS identifies the locations that a proposed project may have an effect on.

EPA - Environmental Protection Agency, responsible for the nationwide enforcement of environmental regulations.

Equal-loudness contour - For a specified sound listened to in a specified manner, a curve that shows the related values of sound pressure and frequency required to elicit a given loudness level for a normal listener.

Equivalent-continuous sound level (average sound level) - The level of a steady sound which, in a stated time period and at a stated time period and at a stated location, has the same A-weighted sound energy as the time-varying sound.

FAA - Federal Aviation Administration, the federal agency that is responsible for the safe and efficient movement of aircraft through the National Airspace System. The FAA has broad legislative authority to create and enforce Federal Aviation Regulations.

FAR - Federal Aviation Regulation, aviation rules and regulations enforced by the FAA.

Fast response - Multiplying the square of the frequency-weighted sound pressure by an exponential term with a nominal time constant of 125 milliseconds. Effectively, this dampens the response of the sound level meter.

FBO - Fixed based operator, airport businesses that offer aviation services and products such as aircraft rental, sales, fueling, flight instruction, and aircraft service and maintenance.

FCM - Flying Cloud Airport

FICAN - Federal Interagency Committee on Aviation Noise, provides a forum for debate over future research needs to better understand and control aviation noise.

Frequency - The number of times that a function periodic in time repeats itself in 1 second (number of cycles per second) or the reciprocal of the period.

GIP - Government Industry Partnership, this program encourages public/private entities to develop, monitor, and maintain GPS ground stations and other technologies.

GIS - Geographic Information Systems, provide services for map production, application development, and spatial analysis specifically in noise-related issues.

GLS - GPS Landing System

GPS - Global Positions Systems, can be used to enhance or improve guided phases of flight, airport capacity, safety and noise impact reduction.

HIRLS - High Intensity Runway Lighting System

HMMH - Harris Miller Miller and Hanson, aviation consulting firm.

HNTB - Howard Needles Tammen and Bergendoff, aviation consulting firm.

IFR - Instrument Flight Rules, aviation rules applied when weather conditions are below the VFR (Visual Flight Rules) minimums.

ILS - Instrument Landing System, accurately guides aircraft to airport runways when flying in IFR conditions.

IMC - Instrument Meteorological Conditions, requires aircraft to fly under IFR.

INM - Integrated Noise Model, a computer program developed and distributed by the FAA for the analysis of subsonic aircraft noise exposure around the nation's airports.

Instantaneous sound pressure level - The difference between the pressure existing at a specified instant and the atmospheric pressure.

LAAS - Local Area Augmentation System, ground-based antennas whose precisely known locations are used to correct the satellite signals and provide greater positional accuracy as well as integrity of service to aircraft in the air. Represents the next generation of airspace management and aircraft guidance through the National Airspace System using GPS technologies.

Level - The logarithm of the ratio of a given quantity to a reference quantity of the same kind. The base of the logarithm, the reference quantity, and the kind of level must be indicated.

Leq - Equivalent sound level, represents the total sound exposure for the period of interest or an energy average noise level for the period of interest.

LFLS - Low-Frequency Sound Level, the sum of the maximum unweighted sound pressure levels in the 25-80 Hz one-third octave bands during individual noise events.

Lmax - Maximum Sound Level, the maximum sound level (dB) during a particular noise event.

Lmin - Minimum Sound Level, the minimum sound level (dB) during a particular noise event.

Loudness - The attribute of auditory sensation in terms of which sounds may be ordered on a scale extending form soft to loud.

LTCP - Long Term Comprehensive Plan, targets long-term development needs based future demand levels.

MAC - Metropolitan Airports Commission, owns and operates Minneapolis-St. Paul International Airport and six reliever airports throughout the twin cities.

MASAC - Metropolitan Aircraft Sound Abatement Council, former non-profit organization comprised of airport users and community representatives, which, among other things, discussed noise issues and developed noise abatement recommendations for the MAC to consider.

Masking - The process by which the threshold of hearing for one sound is raised by the presence of another sound.

MC - Metropolitan Council, provides leadership in the effective planning of regional growth and redevelopment.

MOA - Memorandum of Agreement (FAA)

MPCA - Minnesota Pollution Control Agency, state agency responsible for protecting Minnesota's air, water, and land resources from the effects of pollution.

MSP - Minneapolis-St. Paul International Airport

NADP - Noise Abatement Departure Profiles, unique aircraft departure profiles designed to minimize noise impacts on communities.

NAS - National Airspace System

NCP - Noise Compatibility Program, a list of actions the airport proprietor, airport users, local governments, and the FAA propose to undertake to minimize existing and future noise/land use non-compatibilities.

NEM - Noise Exposure Map, describes the airport layout and operation, aircraft-related noise exposure, land uses in the airport environs, and the resulting noise/land use compatibility situation.

NIRS - Noise Impact Routing System, used to optimize flight operations within the National Airspace System to minimize adverse noise impacts on communities.

Noise - Any disagreeable or undesired sound or other disturbance.

Noise reduction - The difference in sound pressure level between any two points along the path of sound propagation. Used at MSP to measure the effectiveness of residential sound abatement treatment.

Octave - The frequency interval between two sounds whose frequency ration is 2.

ODR - Optical Disk Reader

PAC - Policy Advisory Committee, consisted of representatives from Minneapolis, Bloomington, Richfield, Eagan, and Mendota Heights and assisted the MAC in developing and implementing Part 150 program corrective land-use measures.

Part 36 - Federal Aviation Regulation 36, Noise standards: Aircraft type and airworthiness certification.

Part 91 - Federal Aviation Regulation 91, General operating and flight rules.

Part 150 - Federal Aviation Regulation 150, Airport noise compatibility planning.

Part 161 - Federal Aviation Regulation 161, Notice and approval of airport noise and access restrictions.

Pascal - A unit of pressure.

PCA - Point of Closest Approach, closest recorded radar target point between an aircraft and a given Remote Monitoring Tower.

Perceived Noise Level - A rating of the "noisiness" of sound from an aircraft or other noise source.

PFC - Passenger Facility Charge, authority for a commercial service airport to charge each enplaning passenger a facility charge that can be used to preserve or enhance safety, security, capacity, and to reduce noise or to enhance competition among carriers.

Phon - The unit of loudness level.

PRS - Preferential Runway Use System, designating a preferred runway to be used when conditions allow to help reduce non-compatible land uses and to minimize the adverse effect of noise on the communities around the airport. The RUS replaced the PRS.

Receiver - A person(s) or equipment that is affected by sound.

Residual noise - is ambient noise without specific noise. The residual noise is the noise remaining at a point under certain conditions when the noise from the specific source is suppressed.

RMT - Remote Monitoring Tower, system of permanent noise monitors that record noise information from various sites and export the collected data into MAC's ANOMS.

RUS - Runway Use System, a noise mitigation operational procedure that directs as many aircraft as possible over compatible land use areas. The RUS replaced the PRS at MSP.

SEL - Sound Exposure Level, the total sound level someone would experience if all of the sound energy occurred in one second. This allows for comparison of different sound events of different duration.

Single-event Noise Exposure Level - The sound exposure level of a single noise event (such as an aircraft overflight) measured over the time interval between the initial and final times for which the sound level of the single event exceeds the background noise level.

Slow Response - Multiplying the square of the frequency-weighted sound pressure by an exponential term with a nominal time constant of 1 second. Effectively, this dampens the response of the sound level meter.

Sone - The unit of loudness.

Sound - A physical disturbance in a medium (e.g. air) that is capable of being detected by the human ear or the hearing sensation excited by a physical disturbance in a medium.

Sound absorption - (1) The property possessed by material, structures, and objects of converting sound energy to heat, resulting form either propagation in a medium or dissipation when sounds strikes a surface. (2) The process of dissipation of sound energy.

Sound analyzer - An apparatus for the determination of a sound spectrum.

Sound level meter - An instrument, which is used for the measurement of sound level, with standard frequency weighting and standard exponentially weighted time averaging.

Specific noise - noise from the source under investigation, is a component of the ambient noise and can be identified and associated with the specific source.

Spectrum - A description of quantity as a function of frequency.

SPL - Sound Pressure Level, measure of the sound pressure of a given noise source relative to a standard reference value (typically the quietest sound that a young person with good hearing can detect).

Time-constant - The time required for a quantity that varies exponentially with time to increase by the factor [1-(1/e)] or to decrease by the factor 1/e, where e is the base of the natural logarithm (e=2.71828).

Time-weighting - Multiplying the square of the frequency-weighted sound pressure by an exponential term.

VFR - Visual Flight Rules, flight rules that apply when stated weather conditions are above the required minimums.

VMC - Visual Meteorological Conditions, allows aircraft to fly under VFR.

VOR - Very High Frequency Omnidirectional Range, navigational equipment that helps pilots navigate to and from a given VOR station.

WAAS - Wide Area Augmentation System, ground-based antennas whose precisely known locations are used to correct the satellite signals and provide greater positional accuracy as well as integrity of service to aircraft in the air. Given the current difficulties with WAAS, LAAS now has higher priority for implementation at U.S. airports.

X-percentile-exceeded sound level - The fast A-weighted sound level equaled or exceeded by a fluctuating sound level x percent of a stated time period. E.g., L10 represents the sound level which was exceeded 10 percent of the stated time period.