Rosh hasshanah; Feast of Trumpets
The first day of Tishri (October), the seventh month of the Hebrew year, and, next to Yom Kippur, or Day of Atonement, the greatest feast of the Hebrews.
It is ordained in the words "The seventh month, on the first day of the month, you shall keep a sabbath, a memorial, with the sound of trumpets." (Leviticus 23)
It is celebrated as New Year's Day, and is also called Day of Judgment; in preparation for it, the trumpet (shophar) is sounded morning and evening excepting Sabbaths, during the entire preceding month.
New Catholic Dictionary