If I'm talking about someone's voice is raspyness or raspy-ness correct?
The raspyness of Cobain’s voice adds another layer of complexity to the song.
The raspy-ness of Cobain’s voice adds another layer of complexity to the song.
Spelling checker doesn't like raspyness, but raspy-ness doesn't look quite right.
The proper term you're looking for is raspiness. Definitely not raspy-ness, neither raspyness, nor raspi-ness. The Wiktionary lists it, even with quotations backing it up:
The speaking voice was clear and strong with no raspiness, but there was a noticeable rasp in the loud singing voice.
~ 1978, Mavis Douglas, Vocal problems of the young singer
If it is a word it would be spelt raspiness but I'm not sure it is a word. Wiktionary has an entry for it at least.
If it were not actually a dictionary word then raspy-ness as a made up word would be acceptable in casual text.
In this particular instance,
"the rasp of Cobain's voice [...]"
could be an acceptable alternative, where rasp means the harsh sound in question; however, the meaning is subtly changed from referring to the rasping quality of his voice to the rasping sound of his voice.
