Chosen Solution
(iPhone 7). Had lightening port replaced because charging was intermittent. My microphones for outgoing calls and for speaker use were working fine until I had the port replaced. Now, no one can hear me clearly through either speaker or simply handheld-to-ear call. No problems using Bluetooth ear pieces. I took it back to the repair shop. They replaced the port again. Problem persists. They’re telling me it’s the motherboard. How can one know if it’s the motherboard, damage to the microphones during port replacement, or what? Do I just need to give up and get a new phone?
You certainly want to eliminate a faulty replacement Lightning port (which the shop appears to have done). The motherboard issue they are referring to is the Audio IC issue on the iPhone 7, you can read my answer to this question (Replaced my screen, sound not working or vibrate, headphones work tho), just a few minutes ago, for more details. However, the Audio IC issue usually has the complete failure of one or more audio devices, i.e. a microphone, speaker, ear speaker, headphone etc. If your microphone kinda works but has poor quality sound, then I would suspect a modular component failure, in this case the Lightning Port (they may have a bad batch).
