A team of researchers and scientists from multiple institutions in Germany have built a cochlear implant that uses light instead of electricity. The study’s findings — published in the scientific journal Science Translational Medicine — describe the working of the new hearing aid and its success rate in lab trials involving rats.
Working of a Cochlear Implant
A typical cochlear implant converts sound waves into electric signals that travel through the ear’s nerve cells. The approach is to go around the damaged hair cells inside the cochlea to restore hearing. However, since the fluid inside the ear is responsible for conducting electricity, the electric signals ultimately generated can lose their regularity, thereby leading to a loss of resolution. People can often experience difficulty in their hearing ability, especially in crowded places, or while listening to music with heavy instruments.
To avoid such a scenario, the researchers considered replacing the electric signals in the hearing aids with light signals, which do not get affected by the fluid in the ear, thus helping people hear better.
In almost all types of cochlear devices, when a sound wave enters the ear, it is directed to a computer chip that furthers the process. After processing the sound waves, the chip directs another device to develop signals directed to the neurons. With this additional device, the team built a new machine capable of generating light using LED chips and sending it to the nerve cells through a fiber cable.
In order to bring this particular change, the nerve cells with the ears would have to be modified in a manner such that it allows them to respond to light rather than electricity. For lab trials, the team of researchers genetically modified rats to grow nerve cells within their ears, which would respond to light.
In this device, the researchers used an implant with 10 LED chips. Before proceeding with the lab tests, they also trained the rats to respond to various sounds before making their hair cells inoperative and implanting the cochlear devices. The implants showed effective results as expected, as the rats were able to respond in similar ways to the same sounds generated. The researchers aim to conduct further research with this new device and begin clinical trials by 2025.