'Trumpet' in the Bible

I was in the Spirit on the Lord's day, and I heard behind me a great voice, as of a trumpet

After these things I saw, and behold, a door opened in heaven, and the first voice that I heard, a voice as of a trumpet speaking with me, one saying, Come up hither, and I will show thee the things which must come to pass hereafter.

And I saw, and I heard an eagle, flying in mid heaven, saying with a great voice, Woe, woe, woe, for them that dwell on the earth, by reason of the other voices of the trumpet of the three angels, who are yet to sound.

one saying to the sixth angel that had one trumpet, Loose the four angels that are bound at the great river Euphrates.