"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Several iPhone 8 and 8 Plus Owners Report Hearing 'Static Noise' in Earpiece During Calls
According to iPhone 8 Plus owners, "very annoying" static sounds can sometimes be heard from the handset's earpiece during regular cellular calls, but the issue doesn't occur when using headphones or if speaker phone is enabled, which could indicate a software issue rather than a speaker defect. The audible crackling has also been reported when using FaceTime, increasing suspicions that the problem doesn't lie with network carriers. Forum member Jgpsolo describes the issue like so:
It is a high-pitched crackle like an audio pop that happens in the earpiece top speaker intermittently during calls. Some calls are fine and others crackle. It is not audible on earphones or on speakerphone, only through the earpiece. The caller on the other end doesn’t hear it.The problem occurs "with or without WiFi calling, with 4G voice (VoLTE) on or off, with phone noise cancelling enabled or disabled under accessibility, and even with third party VoIP apps (like Acrobits Groundwire), with several different carriers," according to forum member ManuCH in Switzerland.
I don’t know whether this is hardware or software related, but one thing that made me think it’s software related is that if you switch on to speakerphone for a few seconds then back to earpiece, the crackles resolve for the duration of the rest of the call. If this was a hardware issue with the earpiece, doing this shouldn’t make a difference.
Some users have tried performing a hard reset on their iPhone 8 Plus, with mixed results. Apple's support team has advised some owners to restore their phone to factory settings and set up again via iCloud backup, again with variable results. Other users have even reported the same problem on like-for-like replacement devices after exchanging what they thought were faulty handsets.
Apple is apparently aware of the issue and is currently looking into it. We'll update this article as soon as we know more.