This is Dr. David
are you talking about fibrosis of the lungs?
or pulmonary fibrosis? or scar tissue in the lungs?
usually fibrosis of the lungs does not cause loss of voice.
but you could have damage to your recurrent laryngeal nerves which travel through the lungs and mediastinum to get to the vocal cords.
an ENT (otolarygology) doctor evaluation of your vocal cords can see if your vocal cords are paralyzed or not.
have you seen an ENT doctor to check on your vocal cords to see if they are paralyzed?
that is good you are being set up with an ENT doctor.
you should also ask your doctor for a CT scan of your lungs as well to check for compression of the recurrent laryngeal nerves in your chest which could lead to vocal cord paralysis and loss of voice.
I am glad you are going to see a ENT doctor.
they will look down your nose and throat and check if your vocal cords are paralyzed.
you could simply have a vocal cord polyp which can take away your voice.
and the poly can be removed easily.
it might not be the pulmonary fibrosis causing your voice loss.
you are welcome