Some iPhone 7 users are reporting that their phones are creating a whining sound from the back of the phone when the phone is performing some sort of stressful activity.
One of the first reports was from Twitter user Stephen Hackett, who also provided a video that demonstrated the whine quite clearly, coming from the back of his iPhone 7. As per the user, the sound was loud enough to be heard with the phone sitting on the desk, and it was recorded while the phone was syncing with iCloud.
Several other iPhone 7 users also reported that they too were hearing whining of varying degree from their phones under various activities. However, most other people seem to have no issue whatsoever.
The source of the sound is likely to be coil whine of some sort, where under stress some components can vibrate and produce a resonance that is audible. Most processors, especially GPUs, produce a faint amount of coil whine but it’s only an issue if it gets too loud. This was normally not an issue on smartphones until now as the processors just weren’t that powerful but with the latest smartphones reaching laptop level performance, particularly the iPhone 7 that beats some of Apple’s own notebooks in CPU performance, coil whine could be an issue.
Still, this is not acceptable behavior for a smartphone. Fortunately, as per Hackett’s tweet, Apple will replace your device with another one if you’re facing this issue. If this extends beyond a freak incident with a handful of devices, Apple will have to make some design changes to the iPhone 7.