Improving Radio audio cues
The current locational audio system is great and adds an interesting dynamic to the game. The further added layer of adding a radio system and how it's handled is great. I still think some minor improvements could be made. I noticed when the user keys up they hear the same static audio cue that every other player on the same team hears. On most handhelds there is no audio playback during transmission. I suggest instead of the static adding a quick, low volume audio tone every time the user pushes to talk that is only heard from the proximity of the speaker of the radio, not the transmission. The game currently allows teammates to radio back without talking and emit no audio. This means that a player surrounded by enemies could quickly key back to a teammate asking if anybody is left alive.
In a similar vein you could also place the same audio cue at the end of a transmission mimicing a roger beep. (Also having the tone be audible from the speaker of the radio)