Wizer, since you can reproduce beeps your issue doesn't sound like a tangent problem. Check your Clipboard>Options>Preferences>Game Sounds: Microphone. It might have changed to something you don't use. That it happened in flight leads me to suspect you're using a USB microphone/headset which had reset itself because of lack of USB resources.
After seeing you have the right microphone chosen, also go to Clipboard>Options>Preferences>Voice and pull the Microphone Volume slider to max. That will enable the automatic and/or manual Boost setting below it.
By "tangent" I meant the push-to-speak button, I mistranslated the word. Anyhow, Options>Controls>Map Keys/Controllers: Global>Voice Transmit Range/Channel is where you can adjust it.