Boyd’s Bible Dictionary:

(horn). The curved signal horn of the Jews, usually made of the horn of a ram, ox, chamois, or wild goat (Lev. 25:9; Ezek. 33:4-5; 1 Chron. 15:28).

Concise Bible Dictionary:

In Daniel 3:5-15 the word is qeren and signifies “horn or cornet.” In 2 Samuel 6:5 the word is manaanim, and signifies an instrument that makes a tinkling sound on being shaken, as a “sistrum.” In the four other places the word is shophar, which is often translated “trumpet” (1 Chron. 15:28; 2 Chron. 15:14; Psa. 98:6; Hos. 5:8).