Just thinking out loud:

If it's working locally, but not externally, that sounds like some sort of networking issue.

But what do you mean by noise? Not garbly or dropped packets, but added noise?

How are you listening to it, that's different than the recording? Are you on the LAN or over the internet?

If you're on the WAN, it could be some sort of congestion.

If you're on the LAN, it could be an actual bug with a jitterbuffer or something wrong with the network card/driver or local network.

Possible debugging step: get both a local and/or remote PCAP capture. That will let us see the network part. Because the most local audio within freeswitch you are finding fine as per the recordings.