Bible Verses About Trumpet: Heard at Mount Sinai at giving of the law

On the third day, when it was morning, there were thunders and lightnings, and a thick cloud on the mountain, and the sound of an exceedingly loud shofar; and all the people who were in the camp trembled.

All the people perceived the thunderings, the lightnings, the sound of the shofar, and the mountain smoking. When the people saw it, they trembled, and stayed at a distance.