Your sense of hearing is more than just how you listen to music and, importantly, your surroundings. Hearing is the fastest of all your senses. You heard that here first.
Explorer will need: earplugs or earphones
Explorer: Put your earplugs in. If you're using earphones, listen to a song at a volume high enough to dull your sense of hearing. Close your eyes.
Guide: Start by saying or making a noise at a low volume. Increase your volume until your Explorer can hear you.