Public-address systems
Voltage
Electrical impedance
Communication equipment
Magnetic field effects
Control panels
Electrical properties and phenomena
Noise (spurious signals)
Indicator lights
Signal distortion
Headphones
Electrical tolerances
Telecommunication
Frequency response
Signal-to-noise ratio
Performance
Sound intensity
Communication systems (buildings)
Telecommunication systems
Attenuation
Conferences
Dimensions
Electronic equipment and components
Electrically-operated devices
Definitions
Audio systems
Audio equipment
Telecommunication links
Sensitivity
Assembly facilities
Colour
Microphones