Whether you suspect that third-party casings or accessories are to blame, consider removing them from your iPhone and then testing the microphone to see if the sound quality differs with and without them. This includes screen protectors, films, and covers that may obscure the microphone, iSight mic, or iPhone receiver, resulting in poor audio quality or no sound at all.
Update iOS to the most recent version.
If the issue is caused by a software defect, an iOS update may be able to resolve it. Apple usually fixes any problems that are impacting iOS devices with iOS upgrades. As a result, if the issue you're having with your audio or microphone is caused by a software fault or malfunction, and you haven't upgraded your iPhone iOS to the current version yet, now is the time to do so.
- Go to Settings->General->Software Update on your iPhone 7 Plus to see if there are any available software upgrades.
If an update is available, you will receive a notification. To complete the update installation procedure, press the Download and Install option and then follow the onscreen instructions.
