King James Bible Dictionary

Were of a great variety of forms, and were made of divers materials. Some were made of silver (Numbers 10:2), and were used only by the priests in announcing the approach of festivals and in giving signals of war. Some were also made of rams' horns (Joshua 6:8). They were blown at special festivals, and to herald the arrival of special seasons (Leviticus 23:24; 25:9; 1 Chronicles 15:24; 2 Chronicles 29:27; Psalms 81:3; 98:6).

"Trumpets" are among the symbols used in the Book of Revelation (Revelation 1:10; 8:2). (See HORN.)

Was celebrated at the beginning of the month Tisri, the first month of the civil year. It received its name from the circumstances that the trumpets usually blown at the commencement of each month were on that occasion blown with unusual solemnity (Leviticus 23:23-25; Numbers 10:10; 29:1-6). It was one of the seven days of holy convocation. The special design of this feast, which is described in these verses, is not known.

When and how observed
Leviticus 23:24-25; Numbers 29:1-6

Celebrated after the captivity with joy
Nehemiah 8:2; Nehemiah 8:9-12
Feasts

(Numbers 29:1; Leviticus 23:24) the feast of the new moon, which fell on the first of Tisri. It differed from the ordinary festivals of the new moon in several important particulars. It was one of the seven days of holy convocation. Instead of the mere blowing of the trumpets of the temple at the time of the offering of the sacrifices, it was "a day of blowing of trumpets." In addition to the daily sacrifices and the eleven victims offered on the first of every month, there were offered a young bullock, a ram and seven lambs of the first year, with the accustomed meat offerings, and a kid for a sin offering. (Numbers 29:1-6) The regular monthly offering was thus repeated, with the exception of the young bullock. It has been conjectured that (Psalms 81:1) ... one of the songs of Asaph, was composed expressly for the Feast of Trumpets. The psalm is used in the service for the day by the modern Jews. Various meanings have been assigned to the Feast of Trumpets; but there seems to be no sufficient reason to call in question the common opinion of Jews and Christians, that if was the festival of the New Year's day of the civil year, the first of Tisri, the month which commenced the sabbatical year and the year of jubilee.