The 'Audiopilot' feature is a microphone mounted in the interior light overhead console, it monitors the noise level in the car and the road surface etc and changes the volume on the stereo/sound to try and cancel out the background noise,
It's a bit strange at first as it works the same as the GALA speed sensitive volume in the MK4 Golf, i hated that feature and always turned it off, noticed the A3 behaving the same when we first got it, tried to turn it off and found that Bose equipped cars don't use GALA due to having the Audiopilot system, got used to it within a week though and dont even notice it anymore [

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