Definition
The number of complete pressure-wave cycles produced by a vibrating source each second, measured in hertz (Hz). Sound frequency determines the perceived pitch of a sound; higher frequencies produce higher-pitched tones, lower frequencies produce lower-pitched tones. The audible range for the human ear is approximately 20 Hz to 20,000 Hz.
Plain English
How fast a sound wave is vibrating. Fast vibrations sound high-pitched, slow vibrations sound low-pitched, and we measure that speed in cycles per second.
Context Anchor
Pilots encounter sound frequency when listening to engine sounds, propeller sounds, headset audio, warning tones, and radio speech clarity.
Derivation
From the Latin frequentia, meaning 'a crowding together' or 'frequent occurrence.' In sound, it refers to how often the wave cycles repeat each second — the more crowded the cycles, the higher the frequency.
Why Pilots Care
Cockpit warnings, stall horns, marker beacon tones, and radio audio are all designed at specific sound frequencies so pilots can recognize them instantly. Understanding frequency also helps when troubleshooting audio panels, intercoms, or noise-canceling headsets.
Analogy
A large drum makes a low sound because it vibrates slowly. A small whistle makes a high sound because it vibrates quickly. Sound frequency is the count of that vibration rate.
Intuition Check
Sound frequency does not mean how loud the sound is. It means how high or low the sound is in pitch.
Example Sentence 1
The stall warning horn uses a high sound frequency so it cuts through cockpit noise and grabs the pilot's attention.
Example Sentence 2
Higher propeller speed raised the sound frequency heard in the cabin.