How to eliminate high-pitched humming noise?
Hi, I just purchased a pair of QuietPoint Active Noise-Cancelling headphones (ATH-ANC7b). I am using them to reduce exposure to ambient noise in our very busy office, so I just have them turned on with no music playing. They cancel the noise very well, however, I am hearing a constant high-pitched humming noise from the left earpiece. There is occasional noise from the right earpiece, but not as constant (perhaps every 10 or 15 seconds). I am disappointed that noise-cancelling headphones introduce an annoying noise of their own - is this normal? Is there a way to eliminate this?