Can I record my noisy neighbor for legal proposes?

CA is an "all party" state for purposes of recording calls, conversations, etc., and prohibits the use of recorded conversations except to prove violations of the statutes prohibiting it. CA Penal Code §§ 631, 632. But since this isn't a conversation and the neighbor wouldn't expect their noise to be confidential or private, you could argue that their noise was public, and available (too available, in fact) to anyone listening. Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.