As you may know, in natural hearing, sounds travel as vibrations from your outer ear, through the tiny bones of your middle ear, to your inner ear, known as the cochlea. The cochlea is a tiny, fluid-filled, spiral-shaped organ and is responsible for turning sound vibrations into nerve signals, your brain can understand as sound.
Along the whole length of your cochlea, there are thousands of tiny hair cells. Each hair cell corresponds to a specific sound frequency or pitch and works like a light switch. When sound waves move through the cochlea, they rock these hair cells back and forth. This mechanical switching motion from the tip of the hair cell instantly triggers a natural electrical nerve signal at the base of that hair cell, like a switch turning on a light bulb. This nerve signal is then instantly carried along the natural hearing pathway to the brain.
When hearing loss affects the sensory hair cells of your inner ear, this is known as sensorineural hearing loss.