The discussion in Parashat Beha’alotekha concerning the trumpets opens the door to an understanding of the sounding of the shofar on Rosh Ha-shana.
According to one opinion in the Gemara, at the end of Rosh Ha-shana, the unit discussing the trumpets serves as the model from which we deduce the laws of sounding the shofar on Rosh Ha-shana.
The Gemara in Rosh Ha-shana 34b cites Rabba's famous words:
"Rabba said:
The Holy One, blessed be He, said:
Declare before Me, on Rosh Ha-shana, the malkhuyot, zikhoronot, and shofarot.
Malkhuyot – that you may coronate Me over you;
Zikhronot – that the memory of you may come before Me for favor;
And how? Through the shofar."
The structure of this teaching seems strange. Rabba starts by establishing that there are three special blessings that dominate the Rosh Ha-shana prayer service: they are known as "malkhuyot," "zikhronot," and "shofrot." Thereafter Rabba goes on to define the subject of each of them. But when he comes to "shofrot," instead of defining the subject and purpose of the blessing, he simply notes that the blessings are uttered in the context of the shofar blasts!
It would seem, therefore, that the concept and significance of the shofar on Rosh Ha-shana parallels – precisely – the concept and significance of the trumpets. In both cases we are talking about an expression of God's Kingship, where this acknowledgment recalls the nation's favor before God. And in both cases there is an extra dimension to this recollection, insofar as the instrument used for sounding the blast recalls to God an event from Israel's history; an event whose invocation amplifies and intensifies the connection between God and Israel. In our parasha, the event that is recalled is Israel's journeying at God's command in the generation of the desert. On Rosh Ha-shana we sound the shofar to recall the event described in the blessing of "shofrot" – the revelation at Sinai, where "the sound of the shofar grew exceedingly loud."