iPhone microphone issue on speakerphone and other apps

The microphone and the phone receiver must be on different circuits because when i am on a regular phone call my voice is picked up as normal; however, when on speakerphone, facetime, using voice memo, or anything beyond my voice is not picked up. Short of replacing or repairing my phone, im wondering if i can choose to use the phone receiver to pick up my voice during the use of the aforementioned apps and utilities.

[Re-Titled by Moderator]