2. By testing the front microphone located next to the front camera, you can record a video using this camera, and you should hear yourself when you play the video clearly.

3. When your voice is heard very low on a call, there is probably dirt obstructing it.

4. Do you have any Bluetooth connected? Disconnect your Bluetooth and check again to see if it already works correctly.

5. Screen protectors can sometimes be misplaced. Try removing it to see if your microphone works well.

6. Having trouble being heard when making calls or FaceTime? Siri is not listening to you. Primarily you should know that your iPhone has several microphones located on the front, back, and bottom of the phone. Many times you can fix microphone problems by carefully cleaning the holes. Dust will likely accumulate in your iPhone's grooves with use, so cleaning it from time to time is a good option; you will surely win in sound quality.