The loud and unusual noises in a post office that are prohibited by law are determined by the usual decorum and operation of the post office, as opposed to what might be loud or unusual for the person; sufficient evidence that the deft was loud and unusual; no plain error in refusal to consider an audio recording where that recording only covers part of the incident in question.
http://www.opn.ca6.uscourts.gov/opinions.pdf/18a0143p-06.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.