Pressure waves enter the ears through the curved and lobed pinna (everyone's is different like fingerprints). It gauges the vertical contours of an incoming wave to figure out the distance of the sound. The displaced air molecules move through the ear canal and across the membranous ear drum. The vibrations wiggle three tiny bones in the middle ear. They amplify the wave’s energy as it goes into the shell of the inner ear. The wave is then turned into electrical signals by pulsing arrays of hair cells.