Rosh Hashanah: What's in a Sound?

(2) All shofars may be used except for that of a cow, because it is a keren. Rabbi Yose said: Are not all shofars called keren as it says, “When they make a long blast with the ram’s keren [horn]?” (Joshua 6:5).

(3) The shofar used on Rosh Hashanah was that of an ibex, straight, and its mouth was overlaid with gold. There were two trumpets, one on each side of it. The shofar gave a long blast and the trumpets a short one, since the commandment of the day was with the shofar.

(4) On [public] fast days they used shofars of rams, curved, the mouths of which were covered with silver, and there were two trumpets in between them. A short blast was made with the shofars and a long one with the trumpets, because the mitzvah of the day is with trumpets.

(5) The Jubilee is the same as Rosh Hashanah when it comes to blowing [the shofar] and blessings. Rabbi Judah says: on Rosh Hashanah they blow with [a shofar of] rams and on Jubilees with [a shofar] of ibex.