Why can't I hear my voice messages or videos?
Voice messages are played through your speaker or your phone’s receiver. When you lift the phone to your ear, the proximity sensor is tripped and the screen will turn off, just like when you are on a phone call. If you'd like to adjust the volume while listening to the message, keep your phone close to your ear.
Volume settings may differ between apps. Your phone also has separate receiver and headphone volume settings for notifications and media playback through the speaker. If you can't hear anything while the media is playing, try pressing the volume up button on the side of the phone. It's likely that the volume setting for the output you're using is turned all the way down
If your screen goes black and you can’t hear voice messages through the speaker, you might be tripping the proximity sensor. Readjust your hand or fingers and try again.