Although this isn't our hardware, we have some that is nearly identical here on houzz:

And our website: http://www.postframeaccessories.com/flat-track.html.

The hardware itself does not really make a lot of noise unless it is not secured tightly or the trolleys have very little weight hanging from them. The other main factor in noise for sliding doors is the door itself. If it is solid, vibrations from sliding the door will not echo inside the door as it would with a hollow core door.

Feel free to ask us any other questions as sliding doors are our specialty!

so would you say that if used for a bathroom door it will soundproof enough from inside to the outside that it's a good option for use when we want the same door matching a bedroom entrance on the oposite end of the wall, the doors will be 15ft apart sliding in towards the middle of the wall...