Recently my Quietcomfort 35 II headphones have developed a static sound in the right speaker. This started just after I installed the 4.3.6 firmware update. I have the latest 4.5.2 firmware update installed but it made no difference. Most of the time the static is present, but sometimes it's not. This happens when using my iPhone, PC, or even without the headphones connected to any device. When I switch off the noise cancellation the static goes away. I've tried resetting the device, but it didn't help.