iPhone 7 hissing: Probably nothing to worry about

Hissing iPhone 7s under load are likely due to coil noise and damping.

Credit: Spencer Platt/Getty Images

There's a new iPhone, and, predictable as sunrise, there's a reported problem that may or may not gain a -gate suffix. This time, some iPhone 7s seem to be making an audible hissing noise.

Here's an audio clip from Stephen Hackett's iPhone 7. He says the hissing is loud enough that it "can be heard while the phone is sitting on a table." In the audio clip, though, the microphone is probably right up against the back of the iPhone. Hackett says on his blog that Apple Care is replacing his iPhone 7.

Another video by Unbox Therapy puts a mic right up against the back of an iPhone 7 Plus, and then an iPhone 7 and iPhone 6S as well. The iPhone 7 Plus seems to have a louder hiss than the other two.

According to Hackett and a few other reports, the hissing seems to come from behind the Apple logo on the back of the phone, which an iPhone 7 teardown has shown is roughly where the new A10 SoC is located. Hackett says the hissing sound is louder when the iPhone 7 is under load. Some people on social media report that they first noticed the hissing sound while restoring the phone—a process that would put the SoC under heavy load.

As with previous iPhone-related issues, such as bendgate, it's hard to assess whether hissing iPhones are actually widespread—or we're just dealing with the usual social-media/hyperbolic-tech-site echo chamber. There are plenty of reports of iPhone 7 and 7 Plus phones that don't hiss, too.

The hissing is likely some kind of coil noise, which you've probably heard hundreds of times before—but usually from a desktop or laptop or another piece of consumer electronics gadgetry, rather than a smartphone. Coil noise (coil whine) is produced when electrical components hit a specific resonant frequency that causes the circuit to physically vibrate. Usually, the heavier the current the stronger the resonance, which in turn causes a louder acoustic noise. Just about every electric circuit is susceptible to coil noise, and thus it must be damped in some way. It's not unusual for the damping (perhaps a blob of glue) to deteriorate over time.

Another possible cause of the iPhone 7 hissing could be RF interference interacting with the phone's audio system in some way—due to poor shielding of the DAC, perhaps. If the reports are accurate, though—that the sound seems to emanate from behind the Apple logo, rather than the ~~headphone jack~~ speaker—it's probably not that.

Following the first reports of hissing iPhone 7s over the weekend, a few people have also reported similar hissing sounds from earlier iPhones and a few Samsung phones as well.

If you have an iPhone 7 or 7 Plus that hisses, it's probably nothing to worry about—unless it's so noisy that it's intrusive, in which case, as with Hackett, you could try to replace it.