That certainly is a hissing sound. So what is going on here?
Stephen Hackett at 512 Pixels was the first to point out the strange sound emanating from his phone and others immediately confirmed they were having the same issue, including TechCrunch’s Darrell Etherington.
For the moment, there are several theories about why this is happening but no real answers.
Engadget’s Jon Fingas says that “some suspect coil whine or similar electromagnetic effects.” He also points out that it’s not a universal problem because he has “tested an iPhone 7 using 3DMark ‘Ice Storm Extreme,’ a performance benchmark that puts the processor under serious strain, and heard no hissing at all.”
Author and iOS developer Marco Arment has a more poetic take. “It’s the phone equivalent of hearing the fans spin up loudly whenever your Mac’s CPU gets used to its actual potential,” he says.
Apple Insider speculates that it “could involve the RF transmitter or some other form of interference with the speaker system.”
We’ve contacted Apple for confirmation and asked whether they know the cause of this error but have not yet received an answer. In Hackett’s case, Apple is replacing the phone so that may be an option if you are being affected. Sadly, that will also mean you have to wait 5-7 days for a replacement.