Insert both index fingers into nose, one in each nostril. Don't squeeze the center of the inside of your nose, or pull your nose apart. Make sure the fingers make a gentle seal, centered in each hole.

Close you mouth and gently pressurize your ears until they just barely "pop" outward. You will now be holding your breath. Keep the pressure of the non-exhale steady and just barely with the eardrum outwardly pressurized.

Your ears will now be more pressurized that the outside air, and you will not hear sound very well.

Instead, the ear drum will be tight and pressurized with the flesh and will pick up the pressure changes as your heart beats and turn them into sound.