On the third day, when morning came, there was thunder and lightning. A thick cloud was upon the mountain, and a very loud blast of the ram’s horn went out, so that all the people in the camp trembled.
Jewish Publication Society of America Version (JPS1917) - Exodus 19:16 >And it came to pass on the third day, when it was morning, that there were thunders and lightnings and a thick cloud upon the mount, and the voice of a horn exceeding loud; and all the people that were in the camp trembled.