I've got a low humming coming from what seems like the front that changes tone with speed. It's a higher pitch at speed and then lowers as I come to a stop. Any ideas?

Tried searching around here but maybe 'hum' and 'tone' aren't the way other folks have described this.

Dunno if it matters but this is a 2004 S4.

 

It looks like the term "howl" is sometimes used to describe something similar so I'll add that here for the benefit of search engines.

 

Potentially your wheel bearings. It's something in the drivetrain after the transmission because it sounds like it's directly related to road speed.