“Here’s an audio clip (below) 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,” Anthony reports. “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… 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.”
“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,” Anthony reports. “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.”
Read more in the full article here.
MacDailyNews Take: That “hiss” is surprising to some users because they’re simply not used to hearing a desktop-class processor perform inside their phone (and, perhaps, their particular iPhone’s damping is too thinly applied or has deteriorated. If so, and if it’s bothersome, contact Apple).
The main thing about the “iPhone” is that it’s really a pocket Mac. — SteveJack, MacDailyNews, January 9, 2007
Also, as Anthony notes, “There are plenty of reports of iPhone 7 and 7 Plus phones that don’t hiss, too.”