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This Aerospace Recommended Practice (ARP) provides two methods for measuring the aircraft noise level reduction of building façades. Airports and their consultants can use either of the methods presented in this ARP to determine the eligibility of structures exposed to aircraft noise to participate in an FAA-funded Airport Noise Mitigation Project, to determine the treatments required to meet project objectives, and to verify that such objectives are satisfied.

This Aerospace Information Report provides guidelines for hardware design. Guidelines on such items as engine types, test arrangements, and test purposes that would benefit from the use of an inflow control device during static noise testing are outside the scope of this report.

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.

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.

This document describes methods for calculating the attenuation of sound due to line-of-sight blockage or shielding from non-level terrain. This method applies to sound propagating from an airplane to locations on the ground during ground roll, climbout after liftoff, and landing operations. AIR1845 and AIR5662 provides guidance for modeling aircraft noise at airports with flat terrain. In reality, many airports are surrounded by non-level terrain that may result in attenuation (or shielding) of sound at some receptors. This noise blockage can be accounted for with the line-of-sight blockage calculation, based on the difference in propagation path length between the direct path and propagation path over the top of terrain feature. The purpose of this aircraft information report is to provide a method that accounts for the attenuation due to line-of-sight blockage of aircraft noise by terrain features.

This SAE Aerospace Recommended Practice (ARP) provides engineering methods that can be applied to monitoring aircraft noise and operations in the vicinity of airports using either attended or unattended monitoring systems, as well as methods for validation of measurement results from permanent systems. Part 1 provides guidance on the components, installation and administration of permanent systems and guidance on analysis of data collected from temporary monitoring of aircraft noise. Part 2, this part, describes both system screening tests and detailed test methods for validating the data reported by permanently installed systems. This document is intended as a guide toward standard practice and is subject to change with experience and technical advances.

This SAE Aerospace Recommended Practice (ARP) provides engineering methods that can be applied to monitoring aircraft noise and operations in the vicinity of airports using either attended or unattended monitoring systems, as well as methods for validation of measurement results from permanent systems. Part 1 provides guidance on the components, installation and administration of permanent systems and guidance on analysis of data collected from temporary monitoring of aircraft noise. A separate document, Part 2, describes both system screening tests and detailed test methods for validating the data reported by permanently installed systems. This document is intended as a guide toward standard practice and is subject to change with experience and technical advances.

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.

This document describes a practical system for a user to determine observer-to-aircraft distances. These observer-to-aircraft distances can be either closest point of approach (CPA) distances during field measurements or overhead distances during acoustic certification tests. The system uses a digital camera to record an image of the subject aircraft. A method of using commercial software to obtain the distance from such an image is presented. Potential issues which may affect accuracy are discussed.

This document describes a method to calculate noise level adjustments at locations behind an airplane (described by an angular offset or directivity) at the start of takeoff roll (SOTR). This method is derived from empirical data from jet aircraft (circa 2004), most of which are configured with wing-mounted engines with high by-pass ratios (Lau, et al., 2012). Methods are also described which apply to modern turboprop aricraft. Calculations of other propagation-related adjustments required for aircraft noise prediction models are described in AIR1845A, ARP5534, ARP866A, and AIR5662.

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.

Test procedures are described for measuring noise at specific receiver locations (passenger and cargo doors, and servicing positions) and for conducting general noise surveys around aircraft. Procedures are also described for measuring noise level and directivity at noise source locations to facilitate the understanding and interpretation of the data. 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. This document makes no provision for predicting APU or component noise from basic engine characteristics or design parameters, nor for measuring noise of more than one aircraft operating at the same time. No attempt is made to suggest acceptable levels of noise or suitable subjective criteria for judging acceptability. ICAO Annex 16 Volume I Attachment C provides guidance on recommended maximum noise levels.

ARP876 is intended to provide specific recommended procedures for the prediction of gas turbine jet exhaust system noise sources. Procedures are issued as separate sections, to allow for future updating as additional methods, consistent with state-of-the-art, become available.

Test procedures are described for measuring noise at specific receiver locations (passenger and cargo doors, and servicing positions) and for conducting general noise surveys around aircraft. Procedures are also described for measuring noise level and directivity at noise source locations to facilitate the understanding and interpretation of the data. 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. This document makes no provision for predicting APU or component noise from basic engine characteristics or design parameters, nor for measuring noise of more than one aircraft operating at the same time. No attempt is made to suggest acceptable levels of noise or suitable subjective criteria for judging acceptability. ICAO Annex 16 Volume I Attachment C provides guidance on recommended maximum noise levels.

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.

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.