The cochlea resembles a snail shell and is located in the anterior and medial part of the vestibule, consisting of a central cochlear shaft and a surrounding cochlear canal. The cochlear shaft is conical in shape, and from the cochlear shaft protrudes a spiral-shaped bone spiral plate that rotates around the cochlear shaft. Between the bone spiral plate and the outer wall of the cochlear canal is the basilar membrane, and the cochlear canal contains three canaliculi, namely the vestibular stage, the middle stage (i.e., the membranous cochlear canal), and the tympanic stage, in which the upper wall of the middle stage is the vestibular membrane, the lower wall is composed of the bone spiral plate and the basilar membrane, and the outer wall is the spiral ligament. The vestibular and tympanic steps contain ectolymphatic fluid, and the middle step contains the auditory portion of the membranous vagus, which contains endolymphatic fluid. Hearing arises from the excitation of cochlear hair cells, which convert the energy of mechanical stimuli such as sound vibrations into biopotentials that are transmitted to the cerebral cortex through the auditory nerve. When the energy of sound vibration is transmitted to the static cilia of the hair cell, the static cilia fall back to the dynamic cilia at the lateral edge of the top of the cell and deflect, causing shear displacement of the dynamic cilia, which induces a change in the resting potential of the cell membrane (deflection causes the opening of mechanically gated ion channels at the top of the hair cell, allowing an inward flow of potassium ions and producing a change in the resting potential), resulting in excitation of the hair cell. The outer hair cells of the cochlea perform spectral analysis of the incoming sound and translate the frequency of the sound waves into a distance distribution on the basilar membrane, which gradually increases the resonant frequency from the top to the bottom of the cochlea (i.e., low frequency at the top of the cochlea and high frequency at the bottom). This filter effect in the cochlea is also related to the strength of the basilar membrane, which is the narrowest at the base of the cochlea but the strongest, and decreases from the base to the top of the cochlea, while the length of the hair cells and the width of the basilar membrane gradually increase, thus increasing the load on the basilar membrane and decreasing the resonant frequency from the base to the top of the cochlea. The reason why the strength of the basilar membrane changes with width can be visualized as cutting an elastic rubber cord into small sections of different lengths, and then suspending these small short rubber cords without any tension, and going to pull these rubber cords to achieve the same displacement, the shortest leather cord must have the greatest rebound force, which means that the shorter the length of the rubber cord, the greater the strength. The normal human cochlea has a total of 2.5-2.75 coils, while only 1.75 coils exist in the spiral ganglion cells, which can only reach the middle of the second turn of the drum step, and the farther away from the round window, the greater the distance between the inner wall of the drum step and the spiral ganglion. Therefore, the cochlear implant is generally implanted in the 1.5 or 1.25 coils from the bottom of the cochlea to the top of the cochlea, which mainly stimulates the resonant frequency above 1k Hz in the basilar membrane The cochlear implant is usually placed at 1.5 or 1.25 turns from the base of the cochlea to the top of the cochlea, stimulating mainly resonant frequencies above 1k Hz in the basilar membrane. In clinical practice, cochlear electrodes are implanted in the tympanic cavity because an important goal of cochlear electrode design is to stimulate the largest possible number of auditory nerve cells without overlapping each other, and the tympanic cavity is relatively close to the spiral ganglion, but currently it is not possible to implant electrodes directly into the spiral ganglion. There are different theories regarding the location of the implantation of the tympanic bulb, ranging from close to the lateral bulb to hugging the cochlear shaft.