FOREWORD
TABLE OF CONTENTS
1.0 PURPOSE AND SCOPE
1.1 Introduction
1.2 Background
1.2.1 Noise
1.2.2 Communicator Practices
1.2.3 Audio Response
1.2.4 Articulation Index
1.2.5 Absolute (Envelope) Delay
1.2.6 Differential Delay
1.2.7 Overdrive
1.2.8 Intermodulation Distortion
1.3 System Overview
1.3.1 Control of Microphone Input and Output Signals
1.3.2 Cockpit Voice Recorder (CVR) Area Microphones
1.3.3 Control of Received Audio Signlas
1.3.4 Analysis of Problems and Possible Improvement
       Measures
1.3.5 Long-Term Improvements
1.4. System Characteristics - General
1.4.1 Automatic Gain Control and Compression
1.4.2 Sidetone Level Control
1.4.3 Transmission Bandwidth
1.4.4 Reduction of Distortion
1.5 Audio Systems Interface Goals
1.5.1 General Notes
1.5.2 Microphone Input Circuits
1.5.3 Microphone Emulation Output
1.5.4 PA, Receiver, and Interphone Outputs to Audio
       System
1.5.5 Interphone, Headphone and Handset Amplifier
       Outputs from Audio System
1.5.6 Audio Selector Panel and Audio Control
       Panel/Audio Management Unit Input
1.5.7 CVR Output from Audio System
1.5.8
1.5.9 Speaker Output from Audio System
1.6 Assumptions
1.7 Software Considerations
1.8 Test Procedures
1.9 Definitions of Terms
2.0 EQUIPMENT PERFORMANCE REQUIREMENTS AND TEST
       PROCEDURES
2.1.1 Airworthiness
2.1.2 Intended Function
2.1.3 Federal Communications Commission Rules
2.1.4 Fire Protection
2.1.5 Operation of Controls
2.1.6 Accessibility of Controls
2.1.7 Effects of Test
2.1.8 Applicability of Tests to Equipment
2.1.9 Test Equipment
2.2 Performance Requirements - Aircraft Microphones
       (Except for Carbon)
2.2.1 Frequency Response
2.2.2 Distortion
2.2.3 Sensitivity
2.2.4 Noise Level - Microphones, Except CVR Area
       Microphones
2.2.5 Polar Response (CVR Area Microphones)
2.2.6 CVR Microphone Polarity
2.2.7 Insulation Resistance
2.2.8 Microphone Cord
2.2.9 Push-to-Talk Switch
2.2.10 Microphone Drop Resistance - Except CVR Area
       Microphones
2.2.11 Headset/Handset Isolation
2.3 Performance Requirements - Aircraft Headsets,
       Handsets and Loudspeakers
2.3.1 Frequency Response
2.3.2 Distortion
2.3.3 Sensitivity
2.3.4 Impedance
2.3.5 Overload
2.3.6 Power Handling Rating (Loudspeakers)
2.3.7 Insulation Resistance
2.3.8 Headset and Handset Cord
2.3.9 Headset or Handset Drop Resistance
2.3.10 Acoustic Quality
2.3.11 Speaker Polarity
2.3.12 Headsets and Handsets with Active Circuits
2.4 Performance Requirements - Audio System
2.4.1 Rated Output Power
2.4.2 Audio Frequency Characteristics
2.4.3 Distortion Characteristics
2.4.4 Impedance Characteristics
2.4.5 Volume Controls
2.4.6 Output Regulation
2.4.7 Coupling Between Audio Circuits - Crosstalk
2.4.8 Compression
2.4.9 Stability and Short Circuit
2.4.10 Intermodulation Distortion
2.4.11 Audio Noise Level
2.4.12 System Polarity (non-delay phase inversion)
2.4.13 Delays
2.4.14 Overdrive
2.4.15 Listening Test
2.5 Equipment Performance - Environmental Conditions
2.5.1 Temperature and Altitude Tests
2.5.2 Temperature Variation Test
2.5.3 Humidity Test
2.5.4 Shock Tests
2.5.5 Vibration Tests
2.5.6 Magnetic Effect Test
2.5.7 Power Input Tests
2.5.8 Voltage Spike Conducted Test
2.5.9 Audio Frequency Conducted Susceptibility Test
2.5.10 Induced Signal Susceptibility Test
2.5.11 Radio Frequency Susceptibility Test (Radiated and
       Conducted)
2.5.12 Emission of Radio Frequency Energy Test
2.5.13 Lightning Induced Transient Susceptibility Test
2.5.14 Final Distortion Test
2.5.15 Push-to-Talk Switch Life
2.6 Test Procedures - Aircraft Microphones
2.6.1 Conditions of Test
2.6.2 Detailed Test Procedures
2.7 Test Procedures - Aircraft Headsets, Handsets and
       Loudspeakers
2.7.1 Conditions of Test
2.7.2 Detailed Test Procedures
2.8 Test Procedures
2.8.1 Conditions of Test
2.8.2 Detailed Test Procedures
3.0 INSTALLED EQUIPMENT PERFORMANCE
3.1 Equipment Installation
3.1.1 Accessibility
3.1.2 Aircraft Environment
3.1.3 Display Visibility
3.1.4 Dynamic Response
3.1.5 Failure Protection
3.1.6 Interference Effects
3.1.7 Inadvertent Turnoff
3.1.8 Aircraft Power Source
3.2 Installed Equipment Performance Requirements
3.3 Conditions of Test
3.3.1 Power Input
3.3.2 Associated Equipment or Systems
3.3.3 Environment
3.3.4 Adjustment of Equipment
3.3.5 Warm-up Period
3.4 Test Procedures for Installed Equipment
       Performance
3.4.1 Ground Test Procedures
3.4.2 Aircraft System Communications Testing
4.0 EQUIPMENT OPERATIONAL PERFORMANCE CHARACTERISTICS
4.1 Required Operational Performance Requirements
4.1.1 Power Input
4.1.2 Equipment Operating Modes
4.2 Test Procedures for Operational Performance
       Requirements
4.2.1 Power Input
4.2.2 Equipment Operating Modes
4.2.3 Noise-Attenuating Headsets
4.2.4 Self Test
MEMBERSHIP
Appendix A The Level of Audible Noise in Aircraft at
            the Pilot's Position
Appendix B Discussion on the Determination of
            Intelligibility, Articulation Index, and
            Speech Interference Levels
Appendix C Noise Cancellation in Microphones
Appendix D Active Noise Reduction Handsets
Appendix E Couplers
Appendix F References