Over which water is Hashem's voice?
Rashi: It is over Yam Suf - "Yar'em ba'Shamayim" (18:14).
Radak: At Matan Torah, Hashem's voice from Shamayim first went to "Mayim Rabim" - the sea.
Radak (11) #1: It is rain. It is a great wonder - "Oseh Gedolos v'Ein Cheker; ha'Nosen Matar..." (Iyov 5:9-10).
Radak (11) #2: "Mayim" refers to the serenity, abundance and good of the nations.
Malbim: The voice is water that flooded lands.
Why is He called "Kel ha'Kavod"?
Mesilas Yesharim (Perek 19): Even though He does not need our honor, and it is not esteemed in front of Him, we are obligated to honor Him. One who diminishes this where he could have increased, he sins.
What is "Hir'im"?
Radak (11) #1: It is thunder that comes with the rain.
Radak (11) #2: He will destroy them; the remaining will call him "Kel ha'Kavod."
Malbim: They are great thunder claps amidst the flood water.
