The iPhone 6 I have for App testing does when charging. Some devices do it at certain display settings or under certain loads. Modern Smartphones are virtually

The iPhone 6 I have for App testing does when charging. Some devices do it at certain display settings or under certain loads. Modern Smartphones are virtually silent 99% of the time but invariably they'll all whine at some point. I am the type of person who is unsettled until I pinpoint the origin of a sound and my partner will find me with my ear against the wall tracing a drip or creak in the house. I guess I must also still have some high frequency hearing left because I can still hear every electronic device hum at least under certain conditions.