Definition
An electronic amplifier designed to increase the strength of signals within the range of frequencies the human ear can hear, roughly 20 Hz to 20,000 Hz. In aircraft, it boosts low-level audio signals from sources such as radio receivers, intercoms, navigation identifiers, and warning tones to a level strong enough to drive headphones or cabin speakers.
Plain English
A small device that takes a weak sound signal and makes it loud enough to hear clearly through headsets or speakers.
Context Anchor
Seen in aircraft radios, intercom systems, audio panels, and headset audio circuits.
Derivation
‘Audio’ comes from the Latin audire, meaning ‘to hear.’ ‘Amplifier’ comes from the Latin amplificare, meaning ‘to make larger.’ So the term literally means a device that makes hearable signals larger — which is exactly what it does.
Why Pilots Care
Ensures reliable voice communication between pilots, air traffic control, and crew members.
Intuition Check
Do not think of this as simply “making a radio stronger.” An audio-frequency amplifier strengthens the sound signal after it has become an electrical audio signal, so it can be heard through a headset or speaker.
Example Sentence 1
The audio-frequency amplifier in the audio panel boosts the receiver's output so the pilot can hear ATC clearly through the headset.
Example Sentence 2
During the preflight check, the mechanic tested the audio-frequency amplifier to ensure proper intercom operation between cockpit and cabin.