WHat does it mean when a sound is "public domain"?

[DamTheGreat]

I found a sound for use in my WAD on soundbible.com and the description said it is "public domain". It didn't say who created it, just who recorded it. What does that mean credits-wise? Do I credit the person who recorded it?

[Graf Zahl]

"Public Domain" means it's free to use by anybody, even without credit. Common decency of course says you should still give credit if you can.