Credit: Sanna Hedin
Researchers at Linköping University, Sweden, have made several discoveries on the functioning mechanisms of the inner hair cells of the ear, which convert sounds into nerve signals that are processed in the brain. The results, presented in the scientific journal
Nature Communications, challenge the current picture of the anatomical organisation and workings of the hearing organ, which has prevailed for decades. A deeper understanding of how the hair cells are stimulated by sound is important for such matters as the optimisation of hearing aids and cochlear implants for people with hearing loss.
In order to hear sounds, we must convert sound waves, which are compressions and decompressions of air, into electrical nerve signals that are transmitted to the brain. This conversion takes place in the part of the inner ear known as the cochlea, due to its shape, which is reminiscent of a snail shell. The cochlear duct houses the hearing organ, with many hair cells that are divided into outer and inner hair cells. The outer hair cells amplify sound vibrations, which enables us to hear faint sounds and perceive the various frequencies in human speech better. The inner hair cells convert the sound vibrations into nerve signals. In the current study, the researchers have investigated how the conversion takes place. It is, namely, still unclear how the inner hair cells are stimulated by sound vibrations in order to produce nerve signals.