The Torah commands us to blow the Shofar on Rosh HaShanah. Rav Saadiah Gaon gives ten symbolic explanations for blowing the Shofar.
Firstly, Rosh HaShanah marks the day when Hashem created the world. Just like when a person becomes a king trumpets are blown, on Rosh Hashanah we blow the Shofar to show that we accept Hashem as our king. Secondly, Rosh HaShanah is the first of the Aseret Yemei Teshuvah; the Shofar is a reminder, a wakeup call to do Teshuvah. Next, the Shofar reminds us of Har Sinai (see Shemot 19:16), where Bnei Yisrael said “Naaseh VeNishma,” “We will do and [then] we will hear” (Shemot 24:7). By sounding the Shofar, we are reminded to renew our unswerving commitment to keeping the Mitzvot. Additionally, the Shofar reminds us of the urging of several Neviim (which is compared to a Shofar blast; see Yechezkeil 33:4-5) to repent, to fear Hashem, and to beware of the ultimate Day of Judgment. Other reasons include reminding us to pray for the Beit HaMikdash to be rebuilt and of Akeidat Yitzchak.
Most communities (with the exception of the Yemenite community) have the Minhag to blow the Shofar one hundred times. How did this number come about? This is based on the number of letters in the words which Sisera's mother cried while anxiously awaiting her son’s return from battle (see Shoftim 5:28-30).
Why do Ashkenazic communities blow a Tekiah Gedolah, an extended blast, for the last sound? This is done to ensure that the Satan does not accuse us of eating and drinking happily on the Day of Judgment. The Satan knows that the Torah requires only nine Shofar blasts, and he becomes confused when we blow extra ones. He thinks that it might be the Shofar heralding the arrival of Mashiach (Yeshayah 27:13), at which point he despairs of finding guilt with Bnei Yisrael.
We all know that the Satan gets confused every year on Erev Rosh HaShanah when we are particular not to blow Shofar. One year, the Satan was said to be confused on Rosh HaShanah itself. In 1492, the Jews of Spain were given the choices of converting to Christianity, staying and being killed, or leaving the country. Many of the Jews stayed and publicly converted to Christianity yet kept Judaism in secrecy (conversos). They remained loyal to Hashem to the best of their ability under the circumstance. The Jews wanted to hear the Shofar without the non-Jews discovering. Don Fernando de Aguilar, conductor for the royal orchestra in Barcelona, was one such converso. Therefore, he announced that on certain date, which was the first day of Rosh HaShanah, there was going to be a concert of melodies from different nations. The audience contained some of the highest officials of the Inquisition as well as many conversos. The orchestra played the much-loved sounds of the shofar - Tekiah, Shevarim and Teruah. It is said that Don Aguilar confused the Satan better than anybody.
As we hear the many sounds of the Shofar this Rosh HaShanah, we should bear in mind its awesome power, and we certainly should not engage in any conversation or other forms of disturbance during the blowing. In this merit, Hashem may grant us a good and happy year.
-Adapted from The Book of Our Heritage