I see that no one has answered your question. I thought I answered the question about a week ago, but don't see my reply on the website. Sorry about that. Start with visiting a certified au***logist in your grandfather's city/town. The au***logist will test his hearing and recommend the type of hearing aids that are best for him. Most hearing aids today are digital, but there are different models and styles. The au***logist can make the best recommendation. Good luck and again - sorry for the dela*** reply.