Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
Did you hear that sound? It's barely audible (おと). Go ahead and say the word "audible" with the pronunciation of おと to help you to remember this.
There was a loud noise upstairs.
I can hear the sounds of a very good recorder coming from next door.
Have you ever heard the sound that a goldfish makes when it cries?