The Shofar, a well know symbol of Rosh Hashanah, is one of the earliest instruments used in Jewish music. Infact the the Bible refers to the holiday as Yom Teruah (the day of the sounding of the shofar). Usually made from a rams horn, a shofar can also be made from the horns of other animals, including those of a goat or sheep. It is the one musical instrument that has not changed in over 5,000 years. In Biblical times the shofar was blown to announce an important event, such as the alarm of war or the coming of peace. The Great shofar is said to have been sounded during the greatest event in all Jewish history, the giving of the ten commandments to Moses at Mount Sinai (Shavuot).

The blowing of the Shofar is the only specific commandment for Rosh Hashanah. Just as trumpeters announced the presence of their mortal king, the Shofar is used by Jews to proclaim the coronation of the King of King. Thus one of the most important observances of this holiday is hearing the sounding of the shofar in the synagogue.

A total of 100 notes are sounded each day. There are four different types of shofar notes:

• tekiah, a 3 second sustained note
• shevarim, three 1-second notes rising in tone
• teruah, a series of short, staccato notes extending over a period of about 3 seconds
• tekiah gedolah (literally, "big tekiah"), the final blast in a set, which lasts (I think) 10 seconds minimum

The Bible gives no specific reason for this practice. One that has been suggested is that the shofar's sound is a call to repentance. It is an appropriate symbol as it reminds Jews everywhere of the willingness of Abraham to sacrifice his son, Isaac, to fulfill G-ds command. At the last moment G-d ordered Abraham to exchange Isaac with a sacrificial lamb. The shofar is not blown if the holiday falls on Shabbat.