Table of Contents
FOREWORD
TABLEOFCONTENTS
1.0PURPOSEANDSCOPE
1.1Introduction
1.2Background
1.2.1Noise
1.2.2CommunicatorPractices
1.2.3AudioResponse
1.2.4ArticulationIndex
1.2.5Absolute(Envelope)Delay
1.2.6DifferentialDelay
1.2.7Overdrive
1.2.8IntermodulationDistortion
1.3SystemOverview
1.3.1ControlofMicrophoneInputandOutputSignals
1.3.2CockpitVoiceRecorder(CVR)AreaMicrophones
1.3.3ControlofReceivedAudioSignlas
1.3.4AnalysisofProblemsandPossibleImprovement
Measures
1.3.5Long-TermImprovements
1.4.SystemCharacteristics-General
1.4.1AutomaticGainControlandCompression
1.4.2SidetoneLevelControl
1.4.3TransmissionBandwidth
1.4.4ReductionofDistortion
1.5AudioSystemsInterfaceGoals
1.5.1GeneralNotes
1.5.2MicrophoneInputCircuits
1.5.3MicrophoneEmulationOutput
1.5.4PA,Receiver,andInterphoneOutputstoAudio
System
1.5.5Interphone,HeadphoneandHandsetAmplifier
OutputsfromAudioSystem
1.5.6AudioSelectorPanelandAudioControl
Panel/AudioManagementUnitInput
1.5.7CVROutputfromAudioSystem
1.5.8
1.5.9SpeakerOutputfromAudioSystem
1.6Assumptions
1.7SoftwareConsiderations
1.8TestProcedures
1.9DefinitionsofTerms
2.0EQUIPMENTPERFORMANCEREQUIREMENTSANDTEST
PROCEDURES
2.1.1Airworthiness
2.1.2IntendedFunction
2.1.3FederalCommunicationsCommissionRules
2.1.4FireProtection
2.1.5OperationofControls
2.1.6AccessibilityofControls
2.1.7EffectsofTest
2.1.8ApplicabilityofTeststoEquipment
2.1.9TestEquipment
2.2PerformanceRequirements-AircraftMicrophones
(ExceptforCarbon)
2.2.1FrequencyResponse
2.2.2Distortion
2.2.3Sensitivity
2.2.4NoiseLevel-Microphones,ExceptCVRArea
Microphones
2.2.5PolarResponse(CVRAreaMicrophones)
2.2.6CVRMicrophonePolarity
2.2.7InsulationResistance
2.2.8MicrophoneCord
2.2.9Push-to-TalkSwitch
2.2.10MicrophoneDropResistance-ExceptCVRArea
Microphones
2.2.11Headset/HandsetIsolation
2.3PerformanceRequirements-AircraftHeadsets,
HandsetsandLoudspeakers
2.3.1FrequencyResponse
2.3.2Distortion
2.3.3Sensitivity
2.3.4Impedance
2.3.5Overload
2.3.6PowerHandlingRating(Loudspeakers)
2.3.7InsulationResistance
2.3.8HeadsetandHandsetCord
2.3.9HeadsetorHandsetDropResistance
2.3.10AcousticQuality
2.3.11SpeakerPolarity
2.3.12HeadsetsandHandsetswithActiveCircuits
2.4PerformanceRequirements-AudioSystem
2.4.1RatedOutputPower
2.4.2AudioFrequencyCharacteristics
2.4.3DistortionCharacteristics
2.4.4ImpedanceCharacteristics
2.4.5VolumeControls
2.4.6OutputRegulation
2.4.7CouplingBetweenAudioCircuits-Crosstalk
2.4.8Compression
2.4.9StabilityandShortCircuit
2.4.10IntermodulationDistortion
2.4.11AudioNoiseLevel
2.4.12SystemPolarity(non-delayphaseinversion)
2.4.13Delays
2.4.14Overdrive
2.4.15ListeningTest
2.5EquipmentPerformance-EnvironmentalConditions
2.5.1TemperatureandAltitudeTests
2.5.2TemperatureVariationTest
2.5.3HumidityTest
2.5.4ShockTests
2.5.5VibrationTests
2.5.6MagneticEffectTest
2.5.7PowerInputTests
2.5.8VoltageSpikeConductedTest
2.5.9AudioFrequencyConductedSusceptibilityTest
2.5.10InducedSignalSusceptibilityTest
2.5.11RadioFrequencySusceptibilityTest(Radiatedand
Conducted)
2.5.12EmissionofRadioFrequencyEnergyTest
2.5.13LightningInducedTransientSusceptibilityTest
2.5.14FinalDistortionTest
2.5.15Push-to-TalkSwitchLife
2.6TestProcedures-AircraftMicrophones
2.6.1ConditionsofTest
2.6.2DetailedTestProcedures
2.7TestProcedures-AircraftHeadsets,Handsetsand
Loudspeakers
2.7.1ConditionsofTest
2.7.2DetailedTestProcedures
2.8TestProcedures
2.8.1ConditionsofTest
2.8.2DetailedTestProcedures
3.0INSTALLEDEQUIPMENTPERFORMANCE
3.1EquipmentInstallation
3.1.1Accessibility
3.1.2AircraftEnvironment
3.1.3DisplayVisibility
3.1.4DynamicResponse
3.1.5FailureProtection
3.1.6InterferenceEffects
3.1.7InadvertentTurnoff
3.1.8AircraftPowerSource
3.2InstalledEquipmentPerformanceRequirements
3.3ConditionsofTest
3.3.1PowerInput
3.3.2AssociatedEquipmentorSystems
3.3.3Environment
3.3.4AdjustmentofEquipment
3.3.5Warm-upPeriod
3.4TestProceduresforInstalledEquipment
Performance
3.4.1GroundTestProcedures
3.4.2AircraftSystemCommunicationsTesting
4.0EQUIPMENTOPERATIONALPERFORMANCECHARACTERISTICS
4.1RequiredOperationalPerformanceRequirements
4.1.1PowerInput
4.1.2EquipmentOperatingModes
4.2TestProceduresforOperationalPerformance
Requirements
4.2.1PowerInput
4.2.2EquipmentOperatingModes
4.2.3Noise-AttenuatingHeadsets
4.2.4SelfTest
MEMBERSHIP
AppendixATheLevelofAudibleNoiseinAircraftat
thePilot'sPosition
AppendixBDiscussionontheDeterminationof
Intelligibility,ArticulationIndex,and
SpeechInterferenceLevels
AppendixCNoiseCancellationinMicrophones
AppendixDActiveNoiseReductionHandsets
AppendixECouplers
AppendixFReferences Abstract
Describes audio systems response characteristics that affect the intelligibility of air-ground speech communication including review and evaluation of design measures giving promise of audio response characteristics.
