Sounding Shofar During Morning Services During Elul
Arthur L. Finkle
The Code of Jewish Law (Shulhan Arukh, I28:8) instructs that the shofar shall be sounded in the period between rosh hodesh (new month) Elul until after Yom Kippur. The religious rationale was that Moses ascended Mount Sinai to receive the second tablets, dwelt there for 40 days, and descended on the tenth of Tishre, when the atonement was completed. The musical rationale is that the forty-day period provided the necessary practice to develop the appropriate embouchure.
The religious rationale come from the Midrash (Pirkei d'R' Eliezer 45; R. Eliezer ben Hyrcanus (80-118 C.E.), a disciple of Rabbi Yochanan ben Zakai and teacher of Rabbi Akiva):
In rabbinic commentaries, the Rosh (Rabbeinu Asher ben Yechiel, Germany and Spain, 1250 - 1327, ruling at the end of tractate Rosh HaShanah) concludes: "[Indeed,] it is the Ashkenazi minhag (custom) to blow [shofar] throughout the month of Elul, morning and evening, after the prayer [services]."
Commenting on this custom, The Tur (Rabbeinu Yaakov ben Asher, Spain, 1280 - 1345) is in Orach Chayim 581. The Rema, Yosef Karo (Spain, Portugal and Turkey - 1488-1575) brings a variation - blowing only after the morning service (Shacharis). The Mishnah Berurah, an update of religious laws in the Code of Jewish Law, dated approximately 1900) confirms the accepted custom. See www.learnhalacha.com/ElulShofar.pdf
The musical rationale is what any instrumentalist would do preparatory to a performance. See Arthur L. Finkle, The Easy Guide to Shofar Sounding, LA: Torah Aura, 2003