Num 10:1 And the LORD spake unto Moses, saying,
Num 10:2 Make thee two trumpets of silver; of a whole piece shalt thou make them: that thou mayest use them for the calling of the assembly, and for the journeying of the camps.
Num 10:3 And when they shall blow with them, all the assembly shall assemble themselves to thee at the door of the tabernacle of the congregation.
Num 10:4 And if they blow but with one trumpet, then the princes, which are heads of the thousands of Israel, shall gather themselves unto thee.
Num 10:5 When ye blow an alarm, then the camps that lie on the east parts shall go forward.
Num 10:6 When ye blow an alarm the second time, then the camps that lie on the south side shall take their journey: they shall blow an alarm for their journeys.
Num 10:7 But when the congregation is to be gathered together, ye shall blow, but ye shall not sound an alarm.
Num 10:8 And the sons of Aaron, the priests, shall blow with the trumpets; and they shall be to you for an ordinance for ever throughout your generations.
There were only two sons; Eleazar and Ithamar, which may be the reason for only two silver trumpets.
Num 10:9 And if ye go to war in your land against the enemy that oppresseth you, then ye shall blow an alarm with the trumpets; and ye shall be remembered before the LORD your God, and ye shall be saved from your enemies.
Num 10:10 Also in the day of your gladness, and in your solemn days, and in the beginnings of your months, ye shall blow with the trumpets over your burnt offerings, and over the sacrifices of your peace offerings; that they may be to you for a memorial before your God: I am the LORD your God.
The trumpet has a shrill sound. These were about a cubit in length which is about eighteen inches. The size and bore would make the sound high pitched and shrill. They produced one sound , a conical sound like a horn on a car. A modern trumpet has bent tubing to where the sound is not as clear, but there are more harmonics, more notes, sort of like a human voice, but a greater range. The trumpet was made to be heard above the rumble of carts and animals and talking. We will hear the trumpet of the Lord when he calls.
1Co 15:51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
1Co 15:52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
Mat 24:30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
Mat 24:31 And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.