American English Pronunciation Lessons at English Club
English Club has some of the best explanations on how to improve your American English pronunciation using word stress and sentence stress.
The explanations they provide for these key pronunciation rules are very clear.
Most of them include some audio.
When I taught American English pronunciation classes in DC, I frequently recommend English Club to my students.
Many of them wanted to do extra pronunciation practice outside of class.
I like the way English Club’s easy to read charts to explain pronunciation concepts.