"The sound of the shofar is supposed to inspire fear in the hearts of those who hear it. It allows one to dwell upon fear of punishment, to progress from there to fear of doing evil and then to fear of G-d. Finally one arrives at the feeling of awe of G-d."
Read all of them they are quiet profound, the last one in particular....
http://ohr.edu/holidays/rosh_hashana_and_yom_kippur/insights_and_customs/1191
