Well, this is a difficult question. Sometimes it is helpful to have other family members who are noticing the problem assist by providing their observations to your loved-one.
We cannot always motivate the unmotivated, but you can share the isolation that you feel when you try to talk to your husband, and he does not respond or asks you to repeat things routinely. You may have to point out how often you have to repeat what is being said to him.
Many people have negative thoughts when they think of hearing aids and this may be his struggle too. It is usually related to an experience of the past, perhaps with a parent or grandparent.
The truth is that hearing aids are so much better than they ever have been resulting in life-changing, positive experiences for those who are brave enough to seek help. Encourage him to stay engaged with those precious children, grandchildren or even great grandchildren. He will be glad that he did.