another way is with pocket doors that slide away into the walls. You purchase a steel frame that holds the tracks for the doors and is built into the wall.
Pocket doors are sexy and real space savers..but they don't seal. You will also have a hollow space the size of the door in the wall with no sound deadening. I'm in a similar fix..I have a 14' x 22' shop attached to my garage. I've been thinking about converting it into a small studio (moving out of the basement). I too would like to use the studio area as a place were I could rehearse a small band..truth is its just too tight. I think I can make it work as a drum room and control room but I will also need to move windows and doors...might need to steal space from the ajoining 2 bay garage..er, also wife issues! If I were you I would think on it some more...lose the french doors and /or the wife.