I begin the campaign and all works well, however as the dwarf in the docks starts talking, I notice he´s got no voice. No one´s got voices after that point.

Why?

Thanks!

I just checked SOZ and could not come across a dwarf. Does this problem occur in the original campaign? Maybe this can give ideas about the problem.

What is your operating system?
Do you use GOG Galaxy?
Are your video drivers up to date (strangely, I have heard people fixing their sound problems by updating video card drivers.)

Just trying to give a headstart to next person who maybe able to help.

W10, using gog, my drivers are up to date...

The Neverwinter Nights series isn't fully voiced. Generally minor characters are text-only and have no voice-acting.

He's right you should not worry about certain character voices especially minor ones.. It would mostly appear as text and so on.