I put a video of this on my YouTube channel. The series actually started with an OM voice first, a couple of minutes before your recording.
Video here:
https://www.youtube.com/watch?v=mJEkEvfQtcUNotice that the Buzz of the Buzzer continues under the voice. Also note that the voices have different propagation characteristics from the Buzzer. This is obviously a different source form the Buzzer. I assume it was one of the regular Buzzer trolls transmitting a hoax.
You might notice the Lat / Long given, "38870997 N 77055964 V", or 38.870997 N and 77.055964 W, is the coordinates for the Pentagon, in Washington DC. The originator of the hoax has a sense of humor.
T!