So there has been much discussion about the correct pronunciation of my great-uncle's name. Most English speakers say 'Hanns' rhyming with 'pans' or 'tans'. This is not how Hanns said his name, nor how the members of the family called him.
Instead, we say 'Hanns', like Hantz. It should be said quickly, the same way that 'once' is almost snipped at the end, in contrast 'pans' runs on a bit.
So all together now, H-U-N-N-S
Listen to the audio clip below of how Hanns' daughter Annette says father's name: