Ceiling Exhaust Fan -How loud is .5 sones?

BJ,
Yes,the exhaust fan must run when the system is on to get the heat up on attic. Reason I'm looking for maximum quiteness is because I listen to soft music on low volume normally at 2 to 4am. So basically, at these hours, I will hear everything else as well.
I just read an DIY article about an exhaust fan with .5 sones and the author gave a real life example: In his bedroom, the fan ran very quite that he was 10' away and he couldn't tell if it was On or not. That's a very good info for me.

I just read an DIY article about an exhaust fan with .5 sones and the author gave a real life example: In his bedroom, the fan ran very quite that he was 10' away and he couldn't tell if it was On or not. That's a very good info for me.

The guy is either deaf or he lives 200 feet from a major highway. O.5 Sones is loud.

Is your attic finished? If not, I would mount the fan in the attic (not in the ceiling of your listening room) on top of the joists - utilizing good damping material between the fan and the joists (do a search for after-market noise isolation mounting materials/products). You can easily construct a duct between the fan and the ceiling of your listening room -which can also be damped (provided that you don't obstruct air flow). The duct work must be air-tight to insure maximum ventilation – I would suggest avoiding metal/tin duct work, as it is noisy (MDF may be a better solution. Make sure you damp the duct work from the fan, as the ductwork can act like a speaker cabinet – projecting the sound back into your room. This will not eliminate all of the mechanical noise, but it will reduce the noise compared to mounting it directly in your ceiling.

Note: you can also tweak the fan itself with damping materials (i.e.: soft fan/motor mounts, silicone motor mounts, etc.). The thing is, you want to decouple the fan from the mounting area (in this case your house).

Got talked into replacing two bathroom exhaust fans for a good friend and customer some years ago - half way thru the project I understood why his regular handeyman had passed on it.My buddy wanted less racket in the bathrooms of his buisness - found the quietest rated fans available about 6 or 7 years ago.After mucho struggle installed them.Results were: One fan was somewhat quieter than the old unit I replaced - very definitely not inaudible. Second unit was basically pretty much as noisy as when I started because most of the racket was coming from tin vent pipes banging around -couldn't get at these (120+ year old building)- so no joy.
Based on this very limited experience - I'd suggest that none of the "bathroom" fans are going to be quit enough for you. Remote mount the fan and use the flexible "plastic" HVAC duct to get to your room - while I'm sure you can find really quit fans ( try contacting folks who build recording studios)- I think it'll be a "ma hand me the nitro" moment when you see how expensive they are.