Miller creates a dramatic climax in Death of a Salesman at the end of Act II through the use of music, leading to loud music to simulate the car crash.
As the play ends, we see that Willy has been trying to decide if he should commit suicide to provide his family with the insurance money.
The stage directions clearly indicate how music is used to create suspense as the play reaches its exciting climax in Act II.
Suddenly music, faint and high, stops him. It rises in intensity, almost to an unbearable scream. He goes up and down on his toes, and rushes off around the house. (Act 2, Scene 6)
As the music gets louder and louder, the play gets more and more exciting. We know that Willy is about to do it. The music tells us so. The music and sound effects of the crash create a primal response in the audience (and help the reader picture it).