When choosing cochlear implant, we need to consider the effect after implantation, but the effect of cochlear implant is very personalized and cannot be intuitively perceived. So how can we ensure the concrete effect? This requires us to understand the role of various technical parameters of cochlear implant.
1, sound window: As the name implies, the bigger the window, the louder the sound, and the more sound you hear. Everyone has this experience. The acoustic window of cochlear implant refers to the sound range that you can hear at the same time. The larger the range, the more information and sound types you hear. Normal people's ears can capture a lot of information of different sound sizes, distances, types and levels in an instant, and so can cochlear implants. But because the sound windows of mainstream brands are different at 45, 55, 80 and so on. , more or less have sound information. But there is no doubt that the larger the sound window, the larger the sound range that children get, the richer the sound they hear, and most importantly, important information will not be missed. This is like, after the children enter the park or school, the teacher announces an important message during noisy game time or recess. If the ambient sound is too noisy, is the teacher's voice absorbed or "excluded", and the size of the sound window is good or bad.
2. Channel (frequency domain resolution): What is a channel? For example, the early cochlear implant used a single channel design, which is a physical channel. The electrode stimulates the spiral ganglion cells in a single position in the cochlea, and only the monotonous buzzing sound is heard at this time. Correspondingly, the more channels there are, the more stereoscopic, plump and layered the sound will be. Multichannel, that is, the virtual channel technology realized by cochlear implant now, has made a qualitative leap in the early stage. Just like the same song, do you need to say more about the difference between playing with a toy xylophone with only 5 keys and playing with a piano with 88 keys? Theoretically, the more channels, the better, which is closer to the sounds heard by natural people, especially the ability to appreciate music is greatly improved, and even the lyrics can be clearly heard and the tones can be distinguished in a noisy environment. At present, the main brands of cochlear implants on the market have as many as 120 channels, which can identify 460 tones.
3. Detail analysis: Speaking of which, I think of an advertisement I saw a long time ago, saying that Eskimos can distinguish hundreds of whites. Aside from their unique perspective, strong observation and rich imagination, in terms of white alone, this is the resolution of details. In our eyes, monotonous white is extremely complicated in their eyes. To give another simple example, we will pay attention to pixels when buying a mobile phone. The higher the pixels, the clearer the photos we take, which is also the detail resolution. For hearing, what is the difference between the detail resolution of cochlear implant at 400Hz and 5200Hz? After reading the above examples, it is not difficult to understand that the higher the resolution of details, the better the processing and restoration of sound signals, the more realistic the sound, and the closer it is to natural sound. Think about it, if the child is learning English, then in some details such as light tone, swallowing sound, tone and so on. If the resolution of the details of the cochlear implant is not enough, not only can these details not be obtained, but the sound heard will also be deformed.
4. Stimulation rate: What is the stimulation rate? You need to know first, what are the electrodes for? The electrode sequence in the electrode should bypass the damaged hair cells and electrically stimulate the spiral ganglion cells. Who is the part of the cochlea that feels sound? Spiral ganglion cells, of course. Electrodes produce sound by stimulating spiral ganglion cells, so the speed of this stimulation is particularly important. High-frequency accurate stimulation can ensure closer synchronization and normal hearing, and there is no delay in hearing the sound. The higher the stimulation rate, the more accurate the sound collection, synthesis, detail processing and original signal preservation, the better the sound reduction, fidelity, fineness and hearing sensitivity, and the shorter the delay time of the sound signal, that is, you can hear the sound at the same time. As far as I know, the stimulation rate of cochlear implant electrodes of mainstream brands on the market is between 32,000 times/second and 83,000 times/second.