I have a 75mm and it exhibits that tiny buzz sound when auto focusing. I never really noticed it until someone mentioned that it affects their video recording (since I mainly just use it to shoot stills). I only notice the buzzing sound when I'm in a room that's silent w/ no other ambient noise to be heard. Outdoors it seems inaudible to me. Based on other user's experience I'm guessing this is normal operation. Disappointing that it's not completely silent like they touted it? A little bit, but it's not a deal breaker for me. If it's not the buzzing sound from this lens, it's the soft noise from the OM-D image stabilization, or the aperture chatter from lenses on Olympus bodies. Clearly operational noise doesn't seem to be high on Olympus's list of "things to fix". LOL All in all, the picture quality from the 75mm is fantastic!