Wait…screw me???
As second language learners, our ears and speech organs need a bit of time to process foreign sounds. So when you first try to mimic speech in your target language, you will hear and pronounce sounds wrong.
To make things worse, you’re probably not going to know when you’re doing this.
As I write in my post on “How to Tune Your Foreign Language Vowel Pronunciation“, foreign speech sounds often get magnetized to familiar ones in our perception, so two different sounds will initially sound the exact same to you unless you pay really close attention.
This is why feedback is so important. The first step to improving is awareness. So we need some sort of feedback system to make us aware of the sounds that we are getting wrong.