“To blow the trumpet” means to use the quality of mercy for correction, for bestowal. Usually, blowing the horn is used only on special occasions, on special holidays: for example, on Yom Kippur (Judgment Day). All these cases are described in the Torah.
The sound of the horn symbolizes the need to invoke Bina, the quality of bestowal, which completely conquers and destroys the remnants of egoism that exist in us. After all, the children of Israel have already surrounded and broken through the wall. It is clear that now there will be a final victory over all the seven stages of egoism.
When a person blows a horn, expels air with his breath, which passes through the horn of a kosher animal, then a special quality of mercy is manifested, which corrects egoistic desires, and walls collapse.
Question: What is this cry of the people breaking down the wall? Should all people shout, and only then will the wall fall?
Answer: This is the cry of the soul, a plea to the property that they want to achieve. A cry is not a word, not a song, but the apotheosis of prayer.
From KabTV’s “Secrets of the Eternal Book” 8/12/21