It appears that some iPhone 7s are hissing at their owners.
ArsTechnica reports that a handful of owners, some of which are quite high profile, have reported a hissing noise coming from the their smartphone. The sound seems to emanate from behind the Apple logo, which is roughly where the A10 processor is located.
How loud it is depends on the anecdote, although some claim it can be heard even when laid on a desk. It also appears to be more noticeable when the phone is under load.
Ars speculates that coil whine is the most likely culprit. This is produced when components are put under strain and begin to resonate at a specific frequency and vibrate a little. Dampening is usually employed to minimise this, but the effectiveness of this can vary with every unit. RF interference remains a possibility, too.