Automatic Gain ControlAGC
Definition
A system that automatically adjusts audio input levels to maintain consistent volume.
Automatic gain control dynamically adjusts the amplification of an audio signal to keep it within an optimal range. When the speaker is quiet, AGC boosts the signal; when they are loud, it reduces amplification. This ensures the speech signal stays within the dynamic range expected by the ASR model.
AGC is important because speakers vary in volume, move closer to or farther from the microphone, and change their speaking intensity throughout a session. Without AGC, quiet speech might fall below the noise floor, and loud speech might clip. Most operating systems and audio hardware include AGC, though it can sometimes introduce artifacts if the gain changes too rapidly.