Earlier quoted context omitted.
It's also federal. https://www.law.cornell.edu/uscode/text/18/2511
That would only apply if the jurisdictional predicate (effect on interstate commerce) were met, which I don't think would be the case here.
But really, It's easy. Put the audio online. Make it all public. Obviously, there should be some time constraint, can't expose an ongoing investigation. Maybe a year after charges are filed? Perhaps a year after trial, to avoid messing with jury pools.
I think this is a pretty great general policy. Police record whatever they want. If the police overstep and record stuff that turns out was private, the people are free to sue. Seems like a nice self balancing amount of surveillance.
Secretly stepping on peoples privacy rights is pretty much consequence free. Publicly stepping on peoples privacy makes the line very bright, and easy to avoid crossing. It also plays neatly into the "honest man has nothing to fear" trope.