If the Microphone on your iPhone is not working properly, you should be able to fix the problem using tips as provided below.
Microphone Not Working on iPhone
While the original iPhone came with one Microphone, newer models of iPhone have at least 3 microphones, placed at the top (near speaker grill), rear (near back camera) and at the bottom edge of iPhone.
Once you are familiar with the placement of Microphones, you are in good shape to follow troubleshooting steps as listed below to fix the problem of Microphone not working properly on iPhone.
1. Check iPhone Cover
If you are using a third party iPhone cover, make sure that the cover fits your device properly and it has the right openings for all the speakers on your iPhone.
The holes or opening for bottom microphone need to be perfectly aligned and not covering or blocking the microphone in any way.
2. Clean Microphones
If your iPhone is suffering from muffed or low voice, the problem could be due to any of its Microphones being blocked by dirt or dust particles.
You can use any soft brush or a toothbrush to clean the top, bottom and the rear microphone on your iPhone.
Make sure you are not using excessive force or pressure while cleaning. Also, do not try to insert a toothpick or any other sharp object into the microphone.
3. Restart iPhone
Sometimes, the problem is due to stuck processes and unexplained minor glitches. These can be cleared by Power flushing iPhone.
Power OFF or Shut Down iPhone by going to Settings > General > Shut Down.
Allow iPhone to completely Power OFF > wait for 60 seconds and Restart iPhone by pressing the Power button.
4. Allow Apps to Access Microphone
Go to Settings > Privacy > Microphone and Enable Microphone Access to the required App.
After this, make a call using the VOIP App that you were having problems with and check if the Microphone is now working.
5. Disconnect Bluetooth Devices
The problem could be due to iPhone being connected to wireless headphones, Car’s infotainment system or to External Bluetooth speakers.
Go to Settings > Bluetooth > move the toggle next to Bluetooth to OFF position.
If you do not want to turn OFF Bluetooth, you can individually disconnect Bluetooth devices connected to your iPhone by tapping on the i icon located next to the Bluetooth device.
6. Update iPhone
Sometimes, the problem is due to bugs in Apps or the operating system, for which Apple and the developers release updates.
Make sure your iPhone is up to date with updates by going to Settings > General > Software Update.
On the next screen, tap on Install (if an Update is available).
7. Disable Noice Cancellation
Noise Cancellation, is enabled by default on iPhones to reduce ambient noise while the speaker is holding the receiver to the ear.
While this works well in most situations, it can impact voice quality if you are using a speaker and lying on a couch or bed while speaking.
Go to Settings > Accessibility > Audio/Visual and switch OFF Noise Cancellation.
After this, call someone to check if the microphone is now working properly. If not, make sure you re-enable Noise Cancellation.
8. Reset All Settings
If above methods did not help, you can try to Reset All Settings on your iPhone to Factory Default Settings and see if this helps in fixing the problem.
Make sure you know your WiFi Network Password, as this step erases WiFi Passwords, but it will not delete Apps or any data from your iPhone.
Go to Settings > General > Reset > select Reset All Settings option.
After iPhone restarts, connect to your WiFi Network and see if the Microphone is now working properly.
9. Check Microphones
You can check the Front Microphone by recording a short selfie video and check the rear Microphone by recording a video using the main or the back camera on your iPhone.
To check the bottom Microphone, open the Voice Memo App on your iPhone and record a short voice note holding the bottom microphone close to your mouth.
If the voice is cracking, fading or breaking in any of these videos, you need to get the Microphone on your iPhone examined by Apple Support or any other trained technician.