Do you understand me now?
My son is now almost 4 and happily his speech is very clear, but there are still many sounds that he cannot produce. Which as many parents know it means there are words you just don't understand. For some reason when he chooses one word with a sound he has a hard time with, the other words in the sentence are also hard to understand. Which means there is an entire sentence that is at times in-comprehensive. I ask him to repeat it. Some times 3 times. Then I ask him to sign a word, I ask him to use a different word. And if I still don't get it even after guessing different word, him pointing he gives up and gets very frustrated- and rightly so.
When this happens we take a big breath... Yoga training :) and stop. I ask questions, and try to understand. I guess some more, and then ask him to say it again. Typically by now I understand and we are all very happy.
Once we understand we spend a few minutes on the word that gave him issues. We identify the sound and practice other words with similar sounds. After we go back to the offending word and practice till he feels he can say it well.
It takes time, but we always go back to our roots, repetition, ASL, and big breaths.