It seems so simple. We have ears and we hear don't we! We never give much thought about the process and never have to think about hearing because it's something most of us have always taken for granted. But how do we actually hear?
Sound is made up of a wide range of vibrations. These vibrations are so light that we can't (or rarely) feel them yet they are so wide in range, strength and intensity allowing us to hear different pitches and volumes.
These vibrations travel through the air and are captured by our ears. Our external ears (called Pinna) are shaped just so they funnel these into our ear canal.
From our outer ear the vibrations travel into the ear canal. This channelling enhances the vibrations before they stimulate our ear drum making it vibrate as well. Again, the vibration is so light, yet extremely complex, and we can rarely feel it.
Behind our ear drum, in our middle ear, there is a series of small bones called the ossicles (sometimes called the hammer, anvil and stirrup because of their shape. These are the tiniest bones in our bodies and they move when our ear drum moves strengthening the vibrations even further before transferring them to the oval window – the opening of the cochlea or our inner ear.
The cochlea, about the size of a pea, is filled with fluid. In here there are a series of channels and chambers which contain about 15,000 tiny hair cells. When the fluid moves around these hair cells its stimulates them to create electrical impulses. Different sound wave lengths and strengths stimulate different portions of the cochlea, altogether or section by section, giving us the range of high to low, soft to loud sounds.
The cochlea is linked to the auditory nerve and once electrical impulses are created, multitudes of impulses simultaneously travel from the cochlea along the auditory nerve into the part of our brain where we cleverly interpret these impulses as sound. As yet medical science has not worked out how this process actually happens.
All this happens at a speed of micro-seconds. Even when we get many sounds coming at once our ears are smart enough to decode the vibrations and change them to electrical impulses. As hearing declines this ability becomes weaker.
It is no surprise, that if some loses their ear they find it harder to hear, and as we age our bones sometimes calcify making the ossicles work less effectively. Some people lose the small hairs in their cochlea making it impossible for the cochlea to create the necessary electrical impulses for clear speech or music.
The hearing system is complex and damage can occur in any section. It’s a good idea to have your hearing checked regularly as you age to monitor any hearing loss.