Definition
Mechanical or electrical vibrations that occur within the range of frequencies the human ear can hear, generally between about 20 and 20,000 cycles per second (hertz).
Plain English
Vibrations that move back and forth fast enough that we can hear them as sound.
Context Anchor
Seen in discussions of aircraft noise, vibration, sound, and troubleshooting unusual hums, buzzes, or tones in or around an aircraft.
Derivation
Audio' comes from the Latin audire, meaning 'to hear.' So 'audio-frequency' simply means 'a frequency we can hear.' Pairing it with 'vibrations' tells you these are oscillations fast enough to fall inside the hearing range.
Why Pilots Care
These vibrations often signal mechanical imbalance or wear that can affect flight safety and comfort.
Analogy
A tuning fork is a simple example: it vibrates so fast that your ear hears a tone. Audio-frequency vibrations in an aircraft can work the same way, though the source may be a panel, airflow, engine part, or other component.
Grounding Statement
If something in or on the aircraft shakes many times per second, you may hear it as a buzz or whine rather than feel it as a slow vibration.
Intuition Check
Do not assume “audio-frequency” means the vibration comes from a radio or headset. It means the vibration is in the range that human hearing can detect.
Example Sentence 1
The intercom converts the pilot's voice into audio-frequency vibrations that are sent through the headset speakers.
Example Sentence 2
The mechanic used a vibration analyzer to isolate audio-frequency vibrations caused by an unbalanced propeller.