My bmw transmission is changing gears by itself ow it sounds like it's broken

Hello, it's difficult to imagine what may be causing that noise, so a hands on - eyes on - ears on diagnosis should take place. Perhaps you could bring your vehicle to a shop near you to have someone professionally have a listen? most folks will not charge a fee to listen to the noise or road test with you. Here are some shops near you: https://repairpal.com/repair-shops/bmw-repair-and-service-in-portsmouth-virginia