Hi Kitten, I totally understand how you feel, my mam had motor neurone disease and her speech was the first thing to be affected. She got frustrated that sometimes she was difficult to understand. It was awful when we went christmas shopping and she asked a shop assistant in Boots for a special type of mascara for my sister. The woman didn't answer her, looked at me, and answered in a slow loud voice. My mam had cards to show people that explained that she could fully understand them but had a speech problem, but she never used them. She just stopped bothering to try after the christmas shopping thing. We used gestures and pointing a lot, and laughed as much as we could. But sometimes I had to look away and hold back the tears. Im not sure how openly you talk to him about his illness, but it helped us discussing, how awful it must be for people who have communication problems from birth, and how they overcome the obstacles, this, despite my mams illness, made her feel more determined to not get down about her speech, and perhaps feel grateful that shed had years of not having this problem communicating. My thoughts are with you & your Dad. Good luck.