I had the same issue with my speakers vibrating on anything past level 16. The back of the tv is metal so that is what is causing the vibrating sound. I just ended up buying a sound bar and the problem was solved it sounds so much better. I read on some other forums that it was a defect that was happening with random sets.. Most places like Bestbuy were just exchanging them and people said they didnt experience it again. Unfortunately for me i bought mine @ video & audio center and their customer service sucks. they said they were going to do me a favor by offering to exchange it once some authorized dealer inspected it, which by the way was after they unloaded and brought it in their store saying i could do the exchange at that moment, they then handed me a card to a place in a whole other city like 30 minutes away where i had to drop it off and invest more time into this problem, then wait three days for a response, then pick it up and bring it back to the original store with some slip saying its defective, then wait another 3 days for them to call LG to verify they would honor the warranty. So i guess being without the tv i just bought for like a week was no big deal to them, and their" favor" was that they normally only exchange within 7 days but to help me out they would make an exception and also not charge me a 20% restock fee. I live in california and told them our return policy is 30 days and he basically called me a liar. I will never buy a tv from them again and will tell all my friends to just stick to BestBuy since i have never had a problem with them. Hope this helps.