theology - What did Bnei Yisrael experience at Matan Torah?

I'm having trouble understanding what the Israelites actually experienced at the Revelation at Mt Sinai. Did they all see God? Did they all hear Him? Did they all understand Him? Did they hear all of the '10 Commandments,' some of them, or none of them? Or did only Moshe and/or a few select people experience God directly?

Please source your answers, preferably from the relevant verses.