The text is not quite in public domain, however it is allowed to be posted and redistributed. So an audio recording would be allowed as long as it is not changed. My question is whether this is ok to post on LibriVox because it is also a legal document, and we also encourage use of free software like Audacity, which falls under the GPL.Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
For a follow up question, do all disclaimer and copyright notices belong in the public domain? Because there are a few more I'd like to read, like the Apple and Google terms and conditions. If you can't tell, I'm pretty interested in copyright law, which is part of why I'm here in the first place