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Far-end signal → speaker → mic picks up echo. AEC subtracts predicted echo.
What you're seeing
Speakerphones, conference rooms: audio from far end plays through speaker and gets picked up by the mic. Without AEC, far-end hears themselves with delay → painful echo.
AEC: estimate the speaker→mic impulse response (adaptive filter), subtract predicted echo from mic signal. NLMS, LMS, frequency-domain variants. Modern: deep learning.
★ KEY TAKEAWAY
Speakerphones need acoustic echo cancellation: predict the echo via adaptive filter, subtract it from the mic.
▶ WHAT TO TRY
- Click Start — watch the three signals: far-end (blue), mic raw (red, with echo), mic clean (green).
- Slide Echo strength up — without AEC, far end would hear a delayed copy of themselves.