Q: Is the preservation of the original residual hearing after cochlear implantation a fantasy or a reality? A: About 2% of patients with sensorineural deafness exhibit hearing loss at high frequencies, they maintain hearing at 20-60 dB at low frequencies up to 750 Hz, and at frequencies of 1k and above, hearing loss exceeds 60 dB, to the range of severe – profound deafness, and their understanding of monosyllabic words does not exceed 30C40% even with the best hearing aid conditions after wearing a hearing aid . This group of deaf patients presents a partial hearing impairment characterized by moderate to high frequencies. Although sound amplification had very limited improvement in hearing in this group of patients. However, preserved low-frequency hearing is essential for patients to convey prosodic features, as well as information about the fundamental frequency of speech and the first resonant peak frequency, so that the patient perceives the sound more naturally. Until the last few years, most patients with cochlear implants experienced altered sound quality in the low-frequency region after surgery, accompanied by the loss of residual preoperative low-frequency hearing. For this group of patients, von Ilberg et al. proposed in 1999 the treatment strategy of acoustic electrical stimulation (EAS), which uses electrical stimulation to compensate for sensory cell deficits in the mid- to high-frequency range in combination with sound to stimulate the residual low-frequency region ipsilateral to the cochlear implant recipient. Successful preservation of residual hearing is a prerequisite for the use of EAS. Techniques for preserving residual hearing include: 1) insertion of electrodes at a controlled depth in areas with a hearing loss of more than 65 dB while avoiding damage to the parietal gyrus of the cochlea; 2) opening the cochlea using the principles of flexible surgery (AOS); 3) careful incision of the membranous vagus endothelium with one drop of tretinoin; 4) closure of the cochlea with a temporal fascial flap and fibrin glue immediately after electrode implantation; 5) cochlear opening; and 5. A single dose of 500 mg of prednisolone was administered intravenously prior to cochlear opening; 6. A round window implantation technique was used. These implantation techniques are designed to reduce inner ear damage with the aim of preserving the residual preoperative hearing. Preservation of preoperative residual hearing after cochlear implantation has been carried out in several major hospitals in Beijing and Shanghai, including 301 Hospital in China, with very good results. Currently, Cochlear Australia and MED-EL Austria have launched their respective electro-acoustic co-stimulation devices, the Hybrid S8 System (Cochlear? Hybrid? System) and the EAS Hearing Implant System (MED-EL), respectively, and MED-EL has also launched an integrated cochlear implant system for MED-EL has also launched the MED-EL DUET? device, a combined sound processor that integrates hearing aids and speech processors. In addition, MED-EL Austria has recently introduced new products such as SONATA soft electrodes, which help to improve the rate of residual hearing preservation after cochlear implantation.