Tekiah – single blast to call an assembly.
Shevarim – three short blasts of mourning or a call to repentance…
Teruah – nine short staccato blasts, a call to WAR!
Tekiah Gadolah – Long Great Blast the Call of Messiah!
Numbers 10:9 When you go into battle in your own land against an enemy who is oppressing you, sound a blast on the trumpets. Then you will be remembered by the LORD your God and rescued from your enemies.
Jeremiah 4:19 Oh, my anguish, my anguish! I writhe in pain. Oh, the agony of my heart! My heart pounds within me, I cannot keep silent. For I have heard the sound of the trumpet; I have heard the battle cry.
Ezekiel 33:3 and he sees the sword coming against the land and blows the trumpet to warn the people,
Joel 2:1 Blow the trumpet in Zion; sound the alarm on my holy hill. Let all who live in the land tremble, for the day of the LORD is coming. It is close at hand–
1 Corinthians 14:7 For if the trumpet give an uncertain sound, who shall prepare himself to the battle?
Each Feast of Trumpets the Jews and many Christians rehearse the sound of the shofars/trumpets as listed above. The one command specific to this feast is to hear the sound of the shofar this day. Considering the above scriptures, I believe it wise to rehearse this. As this feast is yet to be fulfilled by our Messiah and this is the way to be ready!