the conduction of sound through the bones of the skull. Two types of bone conduction are recognized. In compressional bone conduction, high-pitched sounds cause the segments of the skull to vibrate individually. The vibrations, by compressing the bony case of the inner ear, stimulate the sensory cells that are involved in perceiving sound waves in the air. In inertial bone conduction, low-pitched sounds vibrate the entire skull, causing it to move while the suspended sensory parts of the inner ear remain at rest. The effect is the perception of sound, just as if airborne compressional waves were moving those sensory parts while the skull was stationary.