This website was created to help people improve their American English pronunciation. At the core is a series of videos explaining in detail how each sound is created, as well as a blog.
This video has excerpts from a pronunciation lesson with my friend from Turkey. We are going of the W sound.
In this video, we are discussing the 'aa' as in 'bat' sound. If you have not already viewed the how-to video on that page, I recommend working through it first.
In this video watch for the movement of the mouth. This student is not used to opening his mouth very wide, but it is very important on certain American English vowels that the jaw drops.