In Leviticus 23, Rosh Hashanah is described as a memorial proclaimed with blasts of a shofar.
Leviticus 23:24 places the observance on the first day of the seventh month, calling it a sacred occasion marked by trumpet-like blasts. The Hebrew wording speaks of a “memorial proclaimed with the blast,” while later Jewish interpretation identifies the instrument as the shofar, a ritual horn traditionally made from a ram’s horn.
The shofar is not the same as the metal silver trumpets used by priests in the biblical Temple. Those trumpets served signaling and ceremonial purposes, whereas the shofar became especially associated with Rosh Hashanah and its themes of divine kingship, remembrance, repentance, and awakening.
A common mix-up is to choose “trumpet” because many English translations use that word for the sound or instrument. In Jewish practice, however, the characteristic Rosh Hashanah instrument is the shofar. Its blasts include tekiah, shevarim, and teruah, with different patterns used in the service.