David seems to be able to directly speak to God at times. Then other times through Prophets. I also am curious as to why God spoke directly to people in the Old Testament but does not today. 

I read through several sites and none give the answer I was looking for. Upon pondering it, it could mean God spoke directly to him, maybe they got that feeling we sometimes get that they NEED to do this thing or that after reflection and prayer. This site goes into that some http://www.libertygospeltracts.com/question/prequest/godspeaksvariety.htm

I really like this sites explanations about many different things. https://rcg.org/youth/biblestudy/0503-gstu.html it explains about why God spoke to ancient peoples in the Old Testament and why it wasn’t as necessary after Jesus came to the Earth and gave us the instruction we need now to live a good life.