Does the verbal component for spellcasting have to be words?

To make a long story short: for my first D&D campaign, I want to create a warlock that had to give up her voice as a part of her deal with her Patron.

As such, she is incapable of speaking, but she can still produce sounds with her mouth. I was wondering if that would incapacitate her from casting spells with a Verbal component.

Do spells needs a specific phrase to be cast, or does gibberish work?