Recently, NASA released over 130,000 hours of audio from the Apollo 11 mission. Why 130,000 hours, you ask? To cut a long story short, various support personnel on the ground were able to communicate over a very elaborate system, known as communications loops. Fortunately, most of these were recorded and are now available to the general public after almost half a century.
This is an invaluable resource for people like myself who are not just interested in the historical aspect, but also the technical side of things. At the moment, this is fairly messy, as the raw multi-track tapes were digitized and then uploaded one channel at a time to archive.org
There are several projects as I understand it being undertaken at the moment to put this in a more digestible order for casual browsers, however if there's anything you are particularly interested in, you can check it out here:
https://archive.org/search.php?query=Ap … Collection
If you're interested in a more general look, there's also the nasa audio collection of which these files are a part. This covers a great number of things including Mercury, Gemini, Apollo, Skylab and space shuttle missions.
If there's anything that you're interested in, feel free to ask here as chances are I can help you out finding it.
Hope this is useful to the curious!