You probably found these verses already but I'll add
Acts 7:38
“This is the having been in the assembly in the wilderness with the Angel speaking to him on Mount Sinai, and [with] our fathers, who received the living oracles to give to us
Galatians 3:19
19 What purpose then [does] the law [serve]? It was added because of transgressions, till the Seed should come to whom the promise was made; [and it] appointed through angels by the hand of a mediator.
Moses was that mediator and prophet who spoke for God to the people- yet scripture shows Moses was with the angel/angels or better word, Messengers, to receive the living oracles of God. As Greg said, realize Angels/Messengers/or God speaking, they are One. So whether you go back and read Exodus 19-20 - know they are one.
Hebrews 1:7
And of the angels He says:
“Who makes the angels of Him spirits
And the ministers of Him of fire a flame.”
So whether theres lightnings, thunders, smoke: they're one.
Hebrews 12:18-19
...and the sound of a trumpet and the voice of words, so that those who heard [it] begged that THE WORD should not be spoken to them anymore.
"in many parts and in many ways of old God spoke to the fathers..." (Hebrews 1:1)
Angels played a major role