Audio problem is a very complex issue and there are several factors to consider why this is happening on your phone. More often than not, this type of issue is sometimes caused if the device has physical defect, dropped to a hard surface or has liquid damage. But if the issue started out of the blue, then there is a chance that a culprit might causing it as well. So, what we have to do now is to isolate all possibilities and consider all factors by doing a step a step procedure until we can formulate a solution and get rid the issue. Here's how:
Step 1: Boot your phone in Safe Mode
As I've mentioned earlier, there is a possibility that a culprit triggered the problem that resulted the device to function abnormally. By booting it in this mode all third-party apps will be disabled temporarily in the system and only the pre-installed ones will be running. So, while in safe mode, try to make a call and observe if the issue still persists. If not, then there's a culprit you need to uninstall to fix the problem.
- Press and hold the Power button.
- Once the Samsung Galaxy S4 logo appears, release the Power button.
- As soon as you release the Power button, press and hold the Volume Down button.
- Continue holding the Volume Down button until the phone has completed the reboot process.
- If you can read 'Safe mode' at the bottom left corner of the screen, release the Volume Down button.
However, if you're still unable to hear the voice caller,proceed to the next step.
Step 2: Perform reset
Since, the problem still happening after booting in safe mode, then the last option that you can do is to perform a reset on your phone. Meaning, we have to bring your phone back to its factory default by deleting all files and data as well as bugs that might preventing your device from functioning normally. But before you follow the steps be sure to transfer first all your files and data to your SD card or personal computer because all of it will be lost. This is how you do the reset:
- Turn off the phone completely.
- Press and hold the Volume Up, Home and Power buttons.
- Release the Power button when the phone vibrates but continue to press and hold the Volume Up and Home buttons.
- When the Android System Recovery screen appears, release both the Home and Volume Up buttons.
- Using the Volume Down button, highlight 'wipe data/ factory reset.'
- Press the Power button to select it.
- Using the Volume Down button again, highlight ' delete all user data.'
- Press the Power key to select it.
- Once the reset is complete, choose 'Reboot system now.'
- Press the Power button to restart the device.
After you do the reset try to make a call again to verify if the issue is fixed. If it's still persists, then we suggest you to seek help from the expert for it might be a hardware problem causing it.