1.What are the parts of the human ear?
The human ear is an organ of hearing and consists of three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the auricle, and the external auditory canal, which we can only see in appearance, is the auricle and the opening of the external auditory canal. The middle ear is a complex cavity of air-containing bones separated from the external ear canal by the tympanic membrane. The middle ear cavity contains three of the smallest bones in the body, called the auditory tuberosities, which connect the eardrum to the inner ear. The inner ear is where the real sound is felt and is buried deep within the hard bone. The inner ear is shaped like a snail, which is why it is also called the cochlea. The inner ear cavity is filled with fluid, and there are many sound-receiving cells in the inner ear, called hair cells. The inner ear is like a piano, and different parts of the ear feel different frequencies of sound. The cochlea is connected to the auditory nerve, which transmits the sound information it receives to the brain.
2. How is hearing produced?
Sound vibrates through the eardrum and external auditory canal, and then through the auditory chain to the inner ear, where the fluid in the inner ear then transmits the sound vibrations to the hair cells. The hair cells feel the sound vibrations and convert them into electrical signals, which stimulate the auditory nerve that innervates them.
3.How many types of deafness are there?
There are three types of deafness depending on the location and nature of the lesion: ① Conductive deafness, which refers to hearing impairment caused by lesions in the outer or middle ear, such as chronic suppurative otitis media, exudative otitis media, congenital malformation of the outer or middle ear, etc. This type of deafness can mostly be restored by treating the original disease. Sensorineural deafness refers to hearing impairment caused by lesions of the inner ear and its auditory nerve, such as sudden deafness, drug-related deafness, noise deafness, senile deafness, Meniere’s disease and congenital inner ear hypoplasia. For this type of deafness, there is no specific treatment except for a few diseases or early stages of the lesion (generally refers to hearing loss within 3 months), where it is possible to recover or improve hearing with medication and other treatments. For this type of deafness, the main purpose is to make good use of the residual hearing by means of rehabilitation. For moderate to severe sensorineural deafness, hearing aids should be fitted. For severe deafness and profound deafness, cochlear implantation is acceptable. ③Mixed deafness refers to the simultaneous existence of lesions in the middle ear and inner ear, such as long-term chronic suppurative otitis media, head trauma, etc.
4.What is prelingual deafness and postlingual deafness?
Deafness that occurs before language is learned is called prelingual deafness, which includes congenital deafness and various kinds of deafness that occur during infancy and childhood. Since language is still developing and learning, if the prelingual deafness does not receive early intervention and rehabilitation, they will be both deaf and mute. Deafness that occurs after language acquisition is called post-linguistic deafness. This type of patient will gradually lose his speech function if there is no sound stimulation all the time.
5. What are the treatment strategies and steps for deaf children?
For deafness, we advocate “early detection, early treatment (or intervention) and early rehabilitation”. Patients should go to a hospital with good audiological construction for systematic hearing examination, so that the correct clinical diagnosis and audiological diagnosis can be made as early as possible. Pure tone audiometry and middle ear acoustic impedance examination are the basic tests necessary, and speech audiometry, brainstem evoked potentials and otoacoustic emissions should also be performed if necessary. For children, early rehabilitation can help them learn to use their residual hearing, help them to develop and learn speech and language normally, and help them to become “deaf but not dumb”, and provide conditions for cochlear implants in the future.
6.What kind of deafness is suitable for cochlear implantation?
Severe or profound sensorineural deafness, including congenital deafness, drug-induced deafness, viral deafness, sudden deafness, noise-induced deafness, and senile deafness, which do not respond well to hearing and speech rehabilitation with hearing aids, are suitable for cochlear implant treatment.
The current consensus on the indications for cochlear implantation are as follows: bilateral severe to profound sensorineural deafness; no significant contraindications; the implant recipient has a desire to recover and the ability to support recovery; and a realistic expectation for cochlear implantation.
7. What are the components of a cochlear implant system?
The cochlear implant is an acoustoelectric conversion device that simulates the function of a cochlea. It consists of a microphone, a speech processor, a transmitter and an implantable part.
The microphone is responsible for receiving the acoustic excitation signal and is usually placed on the back of the outer ear; the Speech Processor, which is similar to a cassette or behind-the-ear hearing aid, is responsible for converting the acoustic signal received by the microphone into an electrical signal in a specified manner and transmitting it to the transmitter. The transmitter is usually magnetically attached to the part of the ear behind the cochlear implant (a metal plate is embedded under the skin behind the patient’s ear during implantation) and transmits the signal from the speech processor into a wireless signal. The implant is then divided into a receiver-stimulator and electrodes, which receive the output signal from the transmitter and, with the help of the electrodes, stimulate the auditory nerve, leading to an auditory response.
8. How does a cochlear implant work?
A microphone worn on the back of the ear receives the sound signal and transmits it to a speech processor. The speech processor digitizes and filters the sound signal, encodes it into an electrical signal according to a certain strategy, and transmits it through the wire to the transmitter coil. The transmitter coil is transmitted by electromagnetic waves to a receiver/stimulator embedded under the scalp. The receiver/stimulator decodes the encoded signal and selectively transmits the corresponding electrical signal to the different electrodes at different sites according to the rules. The electrodes stimulate the adjacent auditory nerve fibers in the form of electrical stimulation, which excites the auditory nerve and transmits sound information to the brain.
9. What is the difference between a cochlear implant and a hearing aid?
A cochlear implant is an artificial organ that replaces the function of the diseased inner ear. It receives sound signals directly, encodes them into electrical stimulation signals, and stimulates the auditory nerve located near the inner ear to produce hearing. The cochlear implant is not affected by the degree of inner ear pathology, so it can be used for severe and profound sensorineural deafness. However, cochlear implants still require the hearing nerve to remain largely intact and require surgical implantation in the inner ear.
Hearing aids are sound amplification devices that compensate for the lack of volume of sound transmitted to the inner ear, as well as amplify sound at speech signal frequencies to a size that can be perceived by the diseased inner ear, depending on the hearing loss in the inner ear. The effectiveness of hearing aids is obviously affected by the degree of inner ear damage, and is not effective for severe and very severe sensorineural deafness.
10. Why does cochlear implantation require the joint participation of different professionals?
Cochlear implantation is not simply a surgical procedure. In order for a cochlear implant to function to its fullest potential, it requires the cooperation of multiple professionals, as well as the patient and family. The cochlear implant process requires the involvement of multiple professionals, as well as the patient and family, in order to maximize the function of the cochlear implant. The cochlear implant process requires the involvement of multiple professionals. They include otologists, audiologists, psychologists, social workers, teachers of deaf children or speech rehabilitation therapists.
11. What is a preoperative cochlear implant evaluation?
Because cochlear implantation is an invasive procedure to the inner ear, there are certain differences in the use of cochlear implants, cochlear implants are expensive, and cochlear implants require long-term maintenance and rehabilitation, a thorough preoperative evaluation is required. The preoperative evaluation should include medical assessment, audiological assessment, hearing aid usage assessment, speech and language assessment, psychological assessment, as well as an introduction to the patient and family to help them understand the cochlear implant and establish appropriate expectations.
12. Is there any danger in cochlear implant surgery?
Cochlear implant surgery involves the implantation of the cochlear implant into the skull behind the ear and the insertion of the electrode set into the cochlea. Cochlear implant surgery carries the same risks as other surgeries such as anesthesia, possible complications such as wound infection and scar formation, and the risks of ear paralysis, taste disturbance, tinnitus, vertigo, and even facial nerve damage that can occur with other ear surgeries.
13. Why is it important to receive a cochlear implant as early as possible?
Auditory language development begins at birth and does not mature until about age 12. For patients with prespeech deafness at an early age, the auditory cortex will not be able to form a normal auditory-speech connection because the auditory system cannot receive normal auditory information, resulting in degeneration of the auditory cortex, which is irreversible and cannot be easily redeveloped through later learning. The older a person is, the more difficult it is to relearn to acquire auditory language skills. In patients with postlingual deafness, if the auditory system cannot receive normal auditory stimulation, it will lead to retrograde degeneration of the nerves in the auditory areas of the cerebral cortex, and therefore they also need to receive a cochlear implant as soon as possible.
Theoretically, for congenitally deaf individuals, the earlier they receive it, the better. In practice, the age limit is not due to safety concerns, but rather due to how early deafness can be detected and ethical considerations.
14. Will I be able to hear normally after receiving a cochlear implant?
Although the cochlear implant is one of the most successful artificial organs available, it does not completely replace the function of the normal inner ear. First of all, the stimulation of the auditory nerve by the cochlear implant is not exactly the same as that produced by the normal inner ear, and requires constant familiarization and learning by the implant recipient in order to develop an understanding of sound. In addition, the cochlear implant requires constant tuning after implantation in order for the recipient to receive the most appropriate stimulation. Therefore, the cochlear implant must undergo a learning process for a certain amount of time before a certain level of hearing ability can be obtained.
15. What is an appropriate expectation?
A cochlear implant does not completely replace the normal cochlea, nor does it allow the recipient to hear exactly as the normal ear does. Cochlear implant recipients need continuous familiarization and learning over time to gain the ability to hear. There are many factors that affect the effectiveness of a cochlear implant, and even recipients with identical conditions may have different results. It is important for recipients and parents to set expectations at an appropriate level to help maintain a normal learning mindset in order to achieve the best possible results.
16. What factors affect the effectiveness of cochlear implants?
The main factors that affect the effectiveness of a cochlear implant include the duration of deafness, age at the time of deafness, age at the time of surgical implantation, cause of deafness, condition of the auditory nerve, desire to regain hearing, appropriate expectations, family support, and hearing and speech rehabilitation.
17. What does it mean to turn on and commission?
When the incision is fully healed after 3 weeks of cochlear implant surgery, the speech processor can be worn. The initial setting of the speech processor through an external programmer is called power on. Once switched on, the cochlear implant is ready for use. As the auditory system gradually adapts and adjusts to the reacquired auditory stimuli and the interaction of the implanted electrode set with the inner ear tissue, the parameters of the speech processor settings are continuously adjusted to suit the needs of the individual, a process known as commissioning. Depending on the effectiveness of the recipient, the initial 1-2 months of start-up are generally debugged once every 1-2 weeks, followed by once every 3-4 weeks, and later increased to once every 1-2 months. After the parameters are stabilized, debugging is kept once a year. Usually, the program parameters will gradually stabilize and will not change too much.
18. Why does the speech processor of a cochlear implant provide several optional programs?
The normal ear has the ability to automatically adjust to a variety of sound environments; current cochlear implants do not yet have this ability. In order to allow the cochlear implant user to get the best results in different sound environments, modern cochlear implants offer several selectable programs. The programmer stores the program settings for different sound environments in the speech processor, and the cochlear implant user can select the appropriate program at will to meet the hearing needs of different environments with a simple button operation.
19. Is the sound heard through the cochlear implant a real, natural sound?
The auditory system’s perception of sound is not only related to the acceptance of sound by the inner ear, but also to the individual’s understanding of sound and the auditory experience they have built up over time. The processing range of the cochlear implant’s speech processor is primarily suited to the speech frequency region, which is different from the perceptual range of the normal human ear. Some sounds in nature are not necessarily within the processing range of the cochlear implant, so the sounds heard through the cochlear implant will be different from those of the normal cochlear implant.
In fact, there are many factors that affect the perception of sound in cochlear implant users, and the description of the sound heard by each user will be different. For prelingually deaf users, the sounds heard are “natural” to the user because there is no previous auditory experience to compare them to. For post-deaf implant users, some describe the sounds as having some variation in pitch, while others describe the sounds as being natural and the same as what they heard before they became deaf. In general, users grow accustomed to the sound produced by the cochlear implant and perceive it as natural and realistic. As technology advances, cochlear implants will provide sounds that are closer to those perceived by the normal ear.
20. Why is post-operative hearing and speech rehabilitation important?
The purpose of a cochlear implant is not only to enable the patient to hear again, but more importantly, to enable the patient to understand and comprehend sounds and learn or regain verbal communication, so post-operative hearing and speech rehabilitation must be emphasized. In adult patients with post-lingual deafness, the post-operative rehabilitation process is relatively easy because the pre-deafness auditory-linguistic system is already established, and they can adapt to and master the sound information provided by the cochlear implant relatively quickly and resume verbal communication. For prelingual deaf patients, the auditory language system is not well developed or not developed at all. Their hearing age, which is only counted from the time they are turned on, is just like a newborn baby, which needs to develop gradually from the process of perceiving sound, distinguishing sound, understanding language and developing speech to establish their auditory language system. Post-operative hearing and speech rehabilitation is an arduous and long-term process that requires the cooperation of professionals and parents.
21. Can cochlear implant users understand speech?
Although the sound provided by the cochlear implant is different from the sound perceived by the normal ear, after adaptation and learning, speech will gradually be understood and the ability to communicate will be learned or restored. Clinical studies have shown that after cochlear implant users have undergone the necessary training and rehabilitation, they are able to understand speech and participate in conversations on a variety of levels. Many users can understand speech without lip reading and can communicate verbally with others over the telephone. For prelingually deaf users, with good auditory language rehabilitation, many children can enter regular school.