In the final scene of the play, Macbeth and Macduff finally confront each other, and Macduff kills Macbeth. Before this though, in their interaction, Macduff states, “…Macduff was from his mother’s womb/Untimely ripped.” (V.viii.19-20). This leads Macbeth to realize that the prophecy is coming true, and that he will die. Once Macduff speaks this line, I would play a sound effect of grave realization. The clip I chose (the sound from 0:05-0:09) represents this well, because of the way that it starts slow, then speeding up and becoming high-pitched, accurately reflecting the building tension of the scene.
Citation
“Sudden Realization Sound Effect | HQ.” YouTube, YouTube, 18 Jan. 2017, http://www.youtube.com/watch?v=UD5wC81R_Pg&t=14s.