If it is his oral tongue that is being grafted - not his base of tongue - then his speech may be affected a little (at first a lot) because it's very swollen. Post op But it does get better - my tongue was getting better then I had radiation and chemo - so now it's swollen again. But my speech gets clearer daily. Just a few of my letters are a little funny still. And my voice is a little deeper but I can speak and I think they removed a 3rd of my tongue - there are people here who've had their entire tongue replaced and can still speak.. Everyone is different- tell your dad to do the surgery because you want him around for as Long as possible. The rest you will deal with. Hugs!!