Bimodal refers to a unilateral cochlear implant user who wears a hearing aid in the opposite ear simultaneously for bimodal listening while still having residual hearing in the opposite ear. As the indications for cochlear implantation have been relaxed, more and more children with cochlear implants still have some residual hearing in the opposite ear. In order to better protect the residual hearing and realize the advantages of binaural hearing, audiologists are now recommending bimodal hearing. So how does bimodal hearing work best? First of all, the hearing aid worn in the opposite ear of the cochlear implant can be the one that the user used before the surgery or purchased anew, but the hearing aid must be debugged before it is put on and the debugging of the hearing aid must be based on the stable cochlear implant program map and the bimodal hearing must be optimized and debugged in both ears to achieve fine-tuning, and ultimately to achieve the optimal match between the two to achieve the most comfortable hearing effect. How to optimize and fine-tune? First, set up a stable program map. A program map is a set of parameters for a speech coding strategy that sets the minimum (T) and maximum (C) values that the child can hear comfortably in different frequency bands based on the child’s response to different loudnesses and pitches, as well as the dynamic ranges between them, which are stored in the speech processor. Each child’s program map is different and individualized, so speech processors are independent and should never be borrowed from each other. Second, choose the right hearing aid. In most cases children after cochlear implant surgery can continue to use their previous hearing aids, but they must be optimally adjusted. The following basic requirements must be in place when choosing a hearing aid: Most residual hearing is low-frequency, so make sure the hearing aid has good low-frequency gain in order to fulfill its function. 1. When doing binaural loudness balancing, the hearing aid is required to have good volume control. 2. When the sound is loud, make sure the whistling is suppressed, i.e. the hearing aid must have acoustic feedback suppression. 3. Have a suitable multi-program, can realize the switch between different programs. 4. With directional microphone to amplify the sound in front. 5.Have linear and wide dynamic range compression (WDRC). 6.With external acoustic input (DAI). Therefore, the hearing aid must have these basic functions, and then for the specific circumstances of the child’s hearing depending on the specific price and performance of the hearing aid, the general requirements to meet the child’s hearing needs can be. In addition, the choice of hearing aid is also related to residual hearing, if the child’s residual hearing is very little, only to focus on the audibility, that is, as long as the child can be heard with a hearing aid, can be helpful to the child’s hearing effect on the good, in this case, if the conditions allow it, you can also consider the bilateral implantation of cochlear implants. If the child’s residual hearing is relatively more, you can consider the audibility and sound quality, that is, in the opposite ear wearing a hearing aid can be heard at the same time, so that the child can better listen to the sound, if the family conditions allow, can be combined with the child’s special and personalized requirements, choose more features of the hearing aid, of course, its price will also be more expensive. Third, hearing aid frequency response optimization. First turn off the cochlear implant and check in the fitting software that all the frequency response curves are comfortable. The audiologist will play a speech to confirm that the listening is comfortable so that the optimal program can be selected. IV. Loudness Balancing. The hearing range after cochlear implant surgery is around 35dB. To perform loudness balancing, you need to turn off the hearing aid and turn on the cochlear implant, play the child a piece of speech in the normal speech range (65dB SPL), adjust the volume of the cochlear implant to the most comfortable value, then turn on the hearing aid, adjust the hearing aid gain, observe the child’s feedback, and check the loudness balance between the two sides of the sound. This is best done by a very experienced audiologist who specializes in both cochlear implant and hearing aid adjustments. V. Verify binaural comfort. The hearing aid and cochlear implant are turned on at the same time, and the child is played a relatively loud sound (85dB SPL) to see if the child can tolerate it. If the child feels uncomfortable, the audiologist will adjust the compression ratio or output. Sixth, fine tuning. If the child becomes uncomfortable during binaural wear, fine-tuning will be done according to the child’s different conditions. In the beginning, the child will be more dependent on the hearing aid, dual-mode wear after hearing aid optimization or fine-tuning, you need to take 2~3 hours a day to train the cochlear implant side alone, and other time to use at the same time. In addition, after stopping using the hearing aid for a period of time, it can still be used, but of course it needs to be optimized and adjusted before use.