just heard some strange talking and buzzing on 5649 USB

[atrainradio]

Can't explain it. Hope it happens again. Anyone else ever hear it?

[atrainradio]

NOW ON 5616 USB. Sounds military

[refmo]

This is Air Traffic Control for North Atlantic Flights.
Gander and New York would be the most commonly heard ATC centers on those two frequencies.
More freqs and info here:   http://wiki.radioreference.com/index.php/MWARA

The buzzing sounds are 'Squawk' codes, used to alert an aircraft crew that ATC is calling them.  
Each aircraft is assigned a unique squawk code.  They will get an alert when their squawk code is received on their radio. This way the crew can keep the volume turned down low on the radio so they don't have to listen to the static and all the other aircraft comms not related to them.
The squawk code is also transmitted by the aircraft to identify the aircraft on RADAR.