What is no noise called?
If there is no noise or sound at all, the word silent is often used.
What is the meaning of Cacophonic?
cacophony \ka-KAH-fuh-nee\ noun. 1 : harsh or discordant sound : dissonance]; specifically : harshness in the sound of words or phrases. 2 : an incongruous or chaotic mixture : a striking combination.