Silver2006525I

Hi,
I am new to this forum and I need to find some answer to my 2006 525 issue. My wife drove my car today and when she comes home, there was this loud noise that I can heard it from the outside. I find a loud static/buzzing noise coming from under the front passenger seat. I took a look under the seat, there were a speaker there, just making loud noise when I insert my key. When I open the door and remove the key the loud noise stop but you can still hear a static sound. Does anyone have this problem? Thanks