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The audio clues that sound when the oponent moves a piece are really important, more so if you are distracted reading chat as streamers do.

They often listen to music.

They are streaming.

They're likely capturing their screen with sound. If they allow the audio output of the game to be captured by the microphone, then the game sounds will play twice. Chess doesn't have very many sounds, but it does have some, e.g. when a piece moves.