Physics
Frequency Spectrum Analysis
Quick fact
Every sound you hear, from a whisper to a symphony, can be represented as a combination of pure sine waves at different frequencies, and the human ear performs a real-time frequency spectrum analysis called the Fourier transform.
Why this is interesting
You hear a single musical chord, but your ear can pick out the individual notes—how does a simple electronic device like a microphone 'see' the same hidden structure?