Re: pronounciation of Roelfs
it might also mean Roelof his son or smething like that.
I am working on the Roelofs family and around 1800 you see sometimes Roelofs & Roels in one document being the same family. Even in one document they are mentioned Roelfs and the same person in a (later) document Roelofs.
This is confusing in searching and we should take care of taking things for granted. So it is not only the pronounciation but there is more behind.
PS the Roelofs family I belong to is living in the eastern part of The Netherlands, near Arnhem, famous of the Battle of Arnhem, in World War II.