All around the world, pronunciation is taught using the ‘Listen and Repeat’ (L&R) approach: the student is asked to listen to his teacher or to a recording, and then has to repeat what he has heard. Many students cannot do this successfully; some can, but their teachers know that it rarely has any real effect on the way they speak.
This is because L&R misdirects the student's attention. He should be focussing on what he is doing with his mouth and what he sounds like as a result. Instead, his attention is fixed 'in his ears' because he is trying to retain what he has heard so that he can copy it.
A typical student attempts this copying process using what his mouth has learnt to do in the past, and this means that he remains in L1. He spends no time exploring what is new about the production of L2. He learns little or nothing from the exercise.
A few students do emerge with good pronunciation. This is because they subvert the L&R process: they consciously look for how to produce new sounds, they watch what they are doing with their mouths, they listen carefully to the results, they practise on their own, and so on. They actively set out to create their L2 pronunciation.
The PronSci approach teaches these good behaviours to everyone.