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Standard

Application of Pure-Tone Atmospheric Absorption Losses to One-Third Octave-Band Data

2013-08-10
CURRENT
ARP5534
This document presents a practical method for calculating atmospheric absorption for wide-band sounds analyzed with one-third octave-band filters, called the SAE Method. The SAE Method utilizes pure-tone attenuation algorithms originally published in ISO 9613-1 and ANSI S1.26-1995 to calculate path-length attenuation at mid-band frequencies. The equations introduced in this standard transform the pure-tone, mid-band attenuation to one-third octave-band attenuation. The purpose of this guidance document is to extend the useful attenuation range of the Approximate Method outlined in ANSI S1.26-1995, and to replace ARP866A. Calculation of sound attenuation caused by mechanisms other than atmospheric absorption such as divergence, refraction, scattering due to turbulence, ground reflections, or non-linear propagation effects, is outside the scope of this document.
Standard

Ground-Plane Microphone Configuration for Propeller-Driven Light-Aircraft Noise Measurement

1988-01-01
CURRENT
ARP4055
The scope of this ARP embraces the description of a configuration for a ground-plane microphone installation that may be used to determine sound pressure levels equivalent to those which would have been measured in an acoustic freefield at the microphone location. The one-third - octave-band center-frequency range over which equivalent freefield sound pressure levels may be obtained is from as low as 50 Hz to at least as high as 10,000 Hz. The specific application of the measurement technique described in this ARP is the determination of the equivalent freefield sound pressure levels of the noise produced by propeller-driven light aircraft, in flight, for sound incidence angles within 30 degrees of the normal to the ground. For larger angles to the normal, additional adjustments may be necessary which are outside the scope of this ARP.
Standard

MEASUREMENT OF EXTERIOR NOISE PRODUCED BY AIRCRAFT AUXILIARY POWER UNITS (APUs) AND ASSOCIATED EQUIPMENT DURING GROUND OPERATION

1979-03-01
HISTORICAL
ARP1307
Test procedures are described for measuring noise at specific locations (passenger and cargo doors, and servicing positions) and for conducting general noise surveys around aircraft. Requirements are identified with respect to instrumentation; acoustic and atmospheric environment; data acquisition, reduction and presentation, and such other information as is needed for reporting the results. Recommended procedures involve recording data on magnetic tape for subsequent processing. The use of tape-recorder/time-integrating analyzer systems avoids the need to average by eye the variations associated with manual readings from sound level meters and octave band analyzers and therefore yields more accurate results. This document makes no provision for predicting APU noise from basic engine characteristics, nor for measuring noise of more than one aircraft operating at the same time.
Standard

MEASUREMENT OF FAR FIELD NOISE FROM GAS TURBINE ENGINES DURING STATIC OPERATION

1990-02-19
HISTORICAL
ARP1846
Recommendations presented in this document are intended primarily for the acquisition of far-field acoustical data. The test engine is to be appropriately configured and operated so that the acoustical signals generated are consistent with the specific objectives of the test. The principal output of the data reduction system is one-third octave band sound pressure levels. However, broader or narrower bandwidth analysis of the recorded data may also be accomplished when appropriate. Although not specifically intended to apply to special purpose engine noise testing (for example, tests involving unique instrumentation or procedures to identify specific noise sources), some of the practices described herein may be appropriate for such testing. Specification of reference conditions is outside the scope of this document although procedures to adjust data to a reference condition are described in 7.2.4.
Standard

MEASUREMENT OF ROTORCRAFT INTERIOR SOUND PRESSURE LEVELS

1993-05-01
HISTORICAL
ARP1964
Satisfactory measurements of noise in personnel-occupied rotorcraft cabins may require test techniques different from those prescribed for other types of aircraft (ARP1323) because rotorcraft operate under significantly different flight conditions. Recommendations of this ARP apply to the recording of acoustical data on magnetic tape and the subsequent processing and analysis of the recorded data.
Standard

Measurement of Far Field Noise from Gas Turbine Engines During Static Operation

2008-03-05
CURRENT
ARP1846A
Recommendations presented in this document are intended primarily for the acquisition of far-field noise data. The test engine is to be appropriately configured and operated so that the sound pressure levels obtained are consistent with the specific objectives of the test. The principal output of the data reduction system is one-third octave band sound pressure levels. However, when appropriate, data may be recorded for purposes of broader or narrower bandwidth analysis.
Standard

Measurement of Rotorcraft Interior Sound Pressure Levels

2012-08-16
CURRENT
ARP1964A
Satisfactory measurements of noise in personnel-occupied rotorcraft cabins may require test techniques different from those prescribed for other types of aircraft (ARP1323) because rotorcraft operate under significantly different flight conditions. Recommendations of this ARP apply to the recording of acoustical data on magnetic tape and the subsequent processing and analysis of the recorded data.
Standard

Method for Predicting Lateral Attenuation of Airplane Noise

2006-04-20
CURRENT
AIR5662
This document describes analytical methods for calculating the attenuation of the level of the sound propagating from an airplane to locations on the ground and to the side of the flight path of an airplane during ground roll, climbout after liftoff, and landing operations. Both level and non-level ground scenarios may be modeled using these methods, however application is only directly applicable to terrain without significant undulations, which may cause multiple reflections and/or multiple shielding effects. This attenuation is termed lateral attenuation and is in excess of the attenuation from wave divergence and atmospheric absorption.
Standard

Procedure for the Calculation of Aircraft Emissions

2009-07-27
CURRENT
AIR5715
This AIR describes procedures for calculating emissions resulting from the main engines of commercial jet and turboprop aircraft through all modes of operation for all segments of a flight. Piston engine aircraft emissions are not included in this AIR. Some information about piston engine aircraft emissions can be found in FOCA 2007. The principal purpose of the procedures is to assist model developers in calculating aircraft emissions in a consistent and accurate manner that can be used to address various environmental assessments including those related to policy decisions and regulatory requirements.
Standard

QUANTITIES FOR DESCRIPTION OF THE ACOUSTICAL ENVIRONMENT OF THE INTERIOR OF AIRCRAFT

1991-03-15
HISTORICAL
ARP4245
This Aerospace Recommended Practice (ARP) defines quantities that may be used to describe various attributes of the sound field in the interior of aircraft. For a particular aircraft, or for a specific situation in a particular aircraft, it may not be necessary to utilize all the quantities included here to provide an adequate description of an aircraft's interior acoustical environment.
Standard

Quantities for Description of the Acoustical Environment of the Interior of Aircraft

2012-08-16
CURRENT
ARP4245A
This Aerospace Recommended Practice (ARP) defines quantities that may be used to describe various attributes of the sound field in the interior of aircraft. For a particular aircraft, or for a specific situation in a particular aircraft, it may not be necessary to utilize all the quantities included here to provide an adequate description of an aircraft's interior acoustical environment.
Standard

TYPE MEASUREMENTS OF AIRCRAFT INTERIOR SOUND PRESSURE LEVELS IN CRUISE

1978-02-01
HISTORICAL
ARP1323
Recommendations of this Aerospace Recommended Practice (ARP) are not intended to satisfy the more detailed and stringent requirements of aircraft design development. Also, they may not be directly applicable to general or private aviation aircraft where special restraints on measurement locations and procedures may exist. However, many of the principles and standards discussed may apply to these aircraft. The recommended procedure for sound pressure level measurements in aircraft involves the recording of data on magnetic tape for subsequent processing and analysis after the flight. Sound level meter/octave-band analyzer measurements, because of inherent inaccuracies associated with manual data readings, are not as precise as those obtained from a tape-recorder/time integrating analyzer system and are, therefore, precluded from this recommended practice.
Standard

TYPE MEASUREMENTS OF AIRPLANE INTERIOR SOUND PRESSURE LEVELS DURING CRUISE

1990-08-01
HISTORICAL
ARP1323A
The primary measurement procedure recommended in this ARP includes the recording of sound pressure signals in the interior of an airplane during steady state cruise conditions with analysis after the flight into octave band (or one-third octave band) sound pressure levels.
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