Every microphone app for using with AUX has a loud noise in the background

A

AC Question

Every app that I download for android with the function of using android as an external microphone (For example, attaching the fone to pc using an AUX cable) produces an noise that is very loud, and I not even need to connect the phone, the app itself produces the noise. It's a weird, very loud noise. I've already disabled wifi and GSM to see if there was any interference, but it wasn't the case.

Is there any hack, app, or configuration to fix that? I can't find a solution anywhere.