A cochlear implant is an electronic device that replaces the function of the human ear and helps people with severe or profound deafness to hear again. Here, patients with severe and profound deafness are those who have severe hearing loss in both ears and poor results with high-powered hearing aids. Cochlear implant technology began in the 1950s, and after decades of development, especially with the emergence of high technology such as biomedical engineering, it has moved from experimental research to clinical application, and has become the only effective treatment for restoring hearing in patients with total deafness. The cochlear implant system consists of three parts: 1. Speech processor The speech processor filters and analyzes the sound and digitizes it into a coded signal. The speech processor sends the coded signal to a transmission coil. The speech processor of the Nucleus 3 system includes the ESPrit3G behind-the-ear speech processor, the SPrint high-powered body-worn speech processor. 2. Cochlear implants Cochlear implants transmit an appropriate amount of electrical energy to a series of electrodes inside the cochlea, which are distributed along the sequence to stimulate the residual auditory nerve fibers in the cochlea. The electroacoustic information is transmitted along the auditory pathway to the brain for compilation. Speech coding strategies Speech coding strategies control the digital processing of environmental sounds and speech. Different encoding strategies focus on different pitch, loudness and temporal cues. Cochlear implant recipients have different preferences for sound quality and show significant improvements in speech perception when using speech encoding strategies designed to meet their individual needs.