Everything vibrates. Think about it. Sound is vibration, music is vibration, your vocal cords vibrate when you say Hallelujah. Even when you whisper, they vibrate softly. You make a quiet sound like a waterfall or wind rushing gently through the trees in your throat. Then you use your tongue and mouth to make the audible sounds as the air passes through. Ha, Le, Lu, Yah. Try it. Do it gently, or crank it up and belt it out.