I would try another ROM to see because I am having somewhat similar issues with no drops at all. I had this in TOUCHWIZ and it was bad. But when I switched to PAC-rom I have different volume issues. Certain (newer I believe) headphones play either double out the phones as well as my integrated speaker and once I had the volume phreak out going up and down inadvertently.
I just love my ROM sooo much that I am dealing with it for now. PAC-rom 4.3 JB nightly updates on Galaxy note 2.
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Rooted GN II Stock TouchWiz ROM