Voice quality can be used to express (often subconscious) feelings, or a personal style of talking.
Other voice qualities may indicate a vocal pathology, or more widespread motor speech disorder.
Creaky voice or glottal fry
This is a very low frequency voice and has a distinct 'creak' or sounds like something frying and sizzling in a hot pan.
This is often employed by speakers, but may be negatively rated by listeners, especially if the speaker is female.