External Auditory Receptor System

The EARS, acronym for External Auditory Receptor System, is a medical device used in the Federation to aid patients who have suffered loss of hearing. The EARS detect sound waves across the entire decibel spectrum, and transmits those signals to the brain through neural implants behind the ears of the individual via brief electrical signals that are conveyed as a burst of acoustic information. The result is a vastly different auditory acuity, with EARS-wearers able to hear in the infra-red and ultra-violet ranges, and beyond. To normal human eyes, the images relayed through the VISOR can seem disorienting and unfamiliar.

Sound waves generated by mechanical forces, such as a bow being drawn across a string, water splashing on a hard surface, or air being expelled across the larynx, are received by the EARS.

• Normally this procedure is accomplished by the eardrum — and, in turn, the three tiny bones of the middle ear — causing each to vibrate. The last of these three bones (the stapes, or "stirrup") jiggles a flexible layer of tissue at the base of the cochlea. This pressure sends waves rippling along the basilar membrane, stimulating some of its hair cells. These cells then send out a rapid-fire code of electrical signals about the frequency, intensity, and duration of a sound. The messages travel through auditory nerve fibers that run from the base of the hair cells to the center of the cochlea, and from there to the brain.

The EARS unit analyzes the incoming sound, bypassing the eardum and middle ear, and transmits the data directly to the auditory nerve fibers. After several relays within the brain, the messages finally reach the auditory areas of the cerebral cortex, which process and interpret these signals as a musical phrase, a dripping faucet, a human voice, or any of the myriad sounds in the world around us at any particular moment.

In order to be able to process sounds at the highest frequency range of human hearing, hair cells must be able to turn current on and off 20,000 times per second. They are capable of even more astonishing speeds in bats and whales, which can distinguish sounds at frequencies as high as 200,000 cycles per second. The EARS, being a mechanical unit, are capable of processing sounds at much higher and lower frequencies. The units must be preset with minimum and maximum values specific to the individual, or the individual may be overwhelmed by the amount of input.

There is one for each ear, comprised of two units each. The first piece is the internal processor with two sets of connectors. The longer smaller ones are the synaptic and neural connectors, and the thicker shorter ones connect the inner unit to the outer unit. The second piece is the outer unit, which actually sits above his ear. It houses the receptors and the manual adjustment controls.