The first occurrence.
And it came to pass on the third day in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceedingly loud; so that all the people that were in the camp trembled. Exo 19:16
The primitive root.
Strong’s H7782, shofar, a concrete noun meaning, “trumpet;” from Strong’s H8231 שפר shaphar, a primitive root meaning, “to polish.” The Ancient Hebrew Lexicon defines it as “a bright or beautiful sight or sound,” listing the English derivatives of spiral, from the shape of the ram’s horn; and spring, from a beautiful sight. The 3-letter root is shin + pey + resh.
shin ש = two front teeth, thus sharp, press, eat, two, again
pey פ, ף = the mouth, thus open, blow, scatter, edge
resh ר = the head of man, thus head, first, top, beginning, man
The story: Pressing (shin) to the mouth to blow (pey) at the beginning (resh) of the month.