Context: David Draiman sings it in the key of F # m. The chord progression is F # m, E, D, A. The first two verses are almost an octave lower than the original and jumped up an octave for the last three verses. His vocal span goes from E2 to A4 in scientific pitch notation.

Question: who sings the sound of silence by disturbed?
Steam of consciousness below:
The relevant information to answer the above question is: David Draiman sings it in the key of F # m.
So, the answer is David Draiman.