My 89 Yr Old Father Had Carotid Surgery Toward The

my 89 yr old father had carotid surgery toward the middle of august this yr., and his throat still hasn't returned to normal. its scratchy and dry and he has a little hard time talking at times and we spoke with the specialist and he said it can take up to 6 months to return to normal and there is a slight chance it may never come completely back? any suggestions on what he can try to get rid of it?