My father, underwent a CABG Operation. After the surgery , he had got secretions in his lungs and they had to be taken out with the use of nebulizers. Once discharged from the hospital, he did not have any breathing complications and was able to cough out the secretions without any aid. However, even after 3 weeks, his voice has not been restored to normalcy. There is loss of voice when he speaks. Is this an area of concen? Kindly advise me on the same.