Why is my Audi 80's engine making a strange whirring noise?

I recently started noticing a strange whirring noise coming from the engine of my Audi 80. It seems to only happen when the car is idling or at low speeds. What could be causing this and how can I fix it?

The most likely cause of this noise is a failing alternator belt. It may be worn out or loose and needs to be replaced. I suggest taking your car to a mechanic to have them check and replace the belt if necessary.