Err ...

I'm seeing "err ..." a lot in my reading (of fiction).  I use "er," myself in my own writing, like, well, "Er, ... Taylor Swift, yeah, that's the ticket!"  It was a signal that the speaker was lying.

Err, in fact, is an actual word.  It means to do something wrong, to make a mistake.  Using 'err' instead of 'er' is just a little distracting.  Google reports that, in the sense of essentially just a non-verbal noise that people make, it is an interjection, indicating hesitation.

If you're an author, and you're writing dialog, it isn't crucial that you try to get the exact sound.  Just write the usual string of letters that has been used to indicate that sound.  In the case of this 'Err' sound, just use 'Er'.

To indicate Hey, slow down, I use Whoa.  Younger authors seem to use "Woe," which looks very wrong.

Another case like this is 'Umm.'  It's been a long time since that word was made respectable; it was spelled just um, but more recently, authors are spelling it umm; the extra letter is not necessary.

If I think of any others, I'll add them in later. 

Kay

P.S.

Wow, means something like That's unexpected!