Why can't I hear sound when I use the voice recorder app? But recorded on video camera, heard sound.

As i said i try to record a video, make a call, call a facebook message, facetime, it hears my voice normally. but when i record voice with voice recorder app and record the screen with open mic I can't hear my own voice I have tried resetting settings. Try the steps you have sent. Try turning on the mic in an app that requires a mic. but doesn't work The app shows in the microphone settings. Not many apps to choose from What should I do? I just thought if my mic had a problem May not hear me from all apps But these are just some apps. Please advise me.

Thank you.