Audiological studies have demonstrated the following advantages of binaural hearing: binaural hearing can improve hearing by 5-10 dB; better localization of sound sources and perception of stereo sound; improved speech recognition in noisy environments; better auditory memory with binaural hearing than monaural, especially short-term memory; and improved communication and social skills in daily life. Many studies have shown that bilaterally deaf patients can benefit from wearing conventional hearing aids (HA) bilaterally. Bilateral cochlear implants (CI) are also available for bilaterally deaf children to improve hearing. Bilateral CI implants have been tried since 1988, either for technical innovation or because of poor hearing performance on the implanted side. In 2004, Laszig reported that bilateral implants accounted for 1% of all CI implants, and bilateral CI implants have become more common than ever. Recently, simultaneous bilateral CI implantation has become the dominant trend, replacing the previous sequential (sequential) CI implantation bilaterally. The benefit of bilateral CI implantation for the patient is that it “guarantees the best hearing outcome after implantation”. The reason for this is to establish the advantages of binaural hearing: 1. Eliminate the head shadow effect: both ears hear different sound intensity due to different positions relative to the sound source, when the sound comes from the left side, the sound heard by the left ear is significantly louder than the right ear, this phenomenon is called the head shadow effect, which is produced by the head barrier and can cause a hearing loss of 6-8 dB. The difference between the two ears in the frequency range is 7 dB, but in the high frequency range can be up to 20 dB. Due to the binaural hearing, each ear can obtain a suitable signal-to-noise ratio, thus eliminating the head shadow effect. 2, retain the binaural sum effect: binaural hearing at the same time will feel the sound louder, binaural hearing sum effect can obtain 3-5dB additional gain. 3, binaural static noise effect: bilateral listening can be through the existence of interaural time difference and interaural intensity difference, the central nervous system through the integration of processing to reduce noise, which can improve the signal-to-noise ratio of about 3dB. 4, sound localization: the same sound source to the existence of the time difference between the two ears, this time difference between the two ears is very important for low-frequency hearing localization. The head shadow effect can form interaural sound intensity (energy spectrum) difference, which is very important for high frequency hearing localization. The combined effect of the above mentioned time difference and energy spectrum difference enables the listener to accurately determine the location of the sound source. 5. Avoid the hearing deprivation effect of unilateral CI implantation: If bilateral deafness is compensated with hearing aids in one ear only, the uncompensated deaf ear may deteriorate over time (this effect was discovered by Gelfand and Silman in 1993). 6. Bilateral implants stimulate the development of the central nervous system more rapidly than unilateral implants. Unilateral cochlear implant recipients need to devote more attention and integrate more sensory systems when listening. In 2004, Kuhn-Inacker reported that in 39 cases of bilateral CI implantation in German prelingually deaf children, all children had better postoperative outcomes than those with unilateral implants, with a mean difference in speech recognition rates of 18.4% between bilateral and unilateral implants, and concluded that although there was no significant correlation between postoperative outcomes and age at first implantation and time difference between implants, early implantation of a second CI was recommended. such as Peters (2007), Wolfe (2007), Scherf (2007), and Galvin (2007), have reported similar findings. To summarize the results of bilateral CI implantation studies, the following conclusions can be drawn: increased speech comprehension in noisy environments, better signal-to-noise ratio by overcoming the cephalic shadow effect; increased speech comprehension in quiet environments; and increased sound localization. And the study showed that bilateral CI implantation should be performed early for better development of auditory and related systems. Feedback from a survey of children with bilateral CI implants: “I can now hear with both ears” “It’s very easy to use” “It’s easy to tell who is talking to me now” ”If I play peek-a-boo, I know where to hide” “People don’t have to pay attention to which side they have to sit on anymore” These are the advantages of bilateral cochlear implants, which are based on normal binaural listening. Because a cochlear implant is ultimately an artificial electronic device that replaces the hearing organ, it is not as natural as listening with your own ears, and there are some inconveniences in daily life. There are also some inconveniences in daily life, such as a certain chance of malfunction (albeit low), the need for maintenance and repair, regular replacement of batteries and other accessories, a few restrictions on daily activities such as swimming, going out in the rain, strenuous exercise, etc. Another important point is that for economic reasons, the above inconveniences will increase with bilateral implants. In conclusion, the advantages are mainly based on the physiological function of hearing, while the shortcomings are mainly due to the fact that cochlear implantation is a technically unsolvable alternative to the hearing organ.