Although learning a second language is not the same as learning one's first, the notion that children learn to pronounce their mother tongue by just copying what they hear around them has been very influential in pronunciation teaching. Children do learn some aspects of pronunciation by imitation, but not everything. Understanding how children do learn to pronounce is important.
What older learners need to do to learn to pronounce English is just as important of course. The key insight here is that pronunciation is a motor skill, and has to be learnt in exactly the same way that other motor skills are mastered.
The academic discipline of Phonetics has a great deal to contribute to pronunciation teaching, but only if we understand that the purposes of phoneticians and teachers are not always the same. For teaching students to pronounce, we need to take our lead from articulatory rather than acoustic phonetics.
If we do so, we can glean some insights that are very helpful to learners.
In teaching, though, it is not enough to understand the subject; understanding the learner and how learning takes place is also essential.
More detail on the theory behind the PronSci approach can be found in the articles on the Downloads page.