Greetings,
I believe you're being prepared for another stage of development. The growling is a test to see how you'll deal with fear--
you can love it to diminish and change it,
tell it you 'see it not there' to blank it out,
growl back or laugh at it to proove your courage, etc.
There's alot written here (index) on how you can approach this test. When I came to this site a year ago I thought the bottom of the list made the most sense for me; it morphed the monster into cartoon form; now I'm generating PUL for any that come by and that startles them into dissolving. The ultimate goal, I believe, is to get them settled but present so you can communicate and find out what spirit underlies (?) that form and help transform it through PUL.
Regarding the buzzing in the second phase of that experience, IMO that's the sound of our own nervous systems as they phase down after the scare, just an inside job, a neuro-reaction.
Congratulations on receiving the test! Must mean you're moving forward!
bets