How shofars became the spiritual soundtrack of Rosh Hashanah

How did this primal instrument become a holiday's spiritual soundtrack?

" The most basic answer is that it makes noise, right? It calls people to attention," said Daniel Picus, an associate professor at Western Washington University in Bellingham who researches religious practices and rituals. "All of the instances in which a shofar is used in the Hebrew Bible, that is what it's doing."