Ursprünglicher Beitrag von: Mrs Fix It ,
Actually, iPhone 7 has four mics: one at the earpiece, and two at the bottom of the phone on either side of the lightning port, and one in the back between the True Tone flash and iSight camera. From what I've read, all are used for noise cancellation but the phones use the closest mic to any sound for clarity. For recordings in stereo (for those with iOS 10 or later), two mics are used for recording sound. Have you tried recording a voice memo to see if it happens there as well? I suggest to also check the areas on the logic board where you connect the cables. Even the most experienced repair person can pop off/damage one of those nano-resistors or jumpers when unseating cables. I've done it a few times myself and it has taken my very strong and trusty magnifying glass to notice that. Very frustrating. Good luck.