Much like understanding the facts about sound, knowing how the ear works can really help you and your child gain confidence in coming to terms with, and managing children’s hearing loss. As well as helping with balance, the job of our ears is to collect and process sounds, then send sound signals that our brains can interpret. But which parts of the ear collect the sounds, which parts process them, and which parts send those sound signals? Well, here are the three sections that make up our ears as well as some basics about the anatomy and functions of them…
The outer ear (pinna) consists of all the external parts of the ear that we can see ourselves and its function is to pick up sounds. The outer ear includes the ear canals, where ear wax is produced. Excess wax build up can cause hearing problems in children with normal hearing, and for children with hearing aids or cochlear implants, it can be a common and persisting problem, but the creation of wax is an important function of the ear. Wax contains chemicals to fight off infection and keep the ears free of dirt and debris, to protect the skin in the ear canal from damage.
Problems with the outer ear such as infections in the ear canal or malformation can cause conductive children’s hearing loss, where an insufficient amount of sound is able to pass through the outer ear to reach the middle ear.
The middle ear begins just after the ear canal and its main function is to take the sounds that are picked up by the outer ear and turn them into vibrations that can sent to the inner ear for further processing. The middle ear begins with the ear drum, a stretched piece of skin just past the ear canal. The ear drum vibrates in response to sound, and stimulates three tiny bones, (the hammer, anvil and stirrup). These bones then help to carry the vibrations onwards to the inner ear.
Problems with the middle ear such as otitis media (glue ear) in the Eustachian tube, a perforated eardrum or fluid build up following a cold can cause conductive hearing loss in children.
The inner ear starts with the cochlea, a small curled tube that’s filled with liquid. When the ossicles (three small bones in the middle ear) vibrate they send a wave through the fluid in the cochlea. This wave or vibration is picked up by microscopic hair cells inside the cochlea which convert the sound to nerve signals that are sent and can be interpreted by our brains.
Inner Ear problems with the cochlea or nerve pathways to the brain can lead to children’s sensorineural hearing loss. Causes can be genetic or due to loud noise, head trauma, disease or other factors. Dead or damaged hair cells cannot regenerate and severity of sensorineural hearing loss can be determined by frequency and extent of hair cell damage. If hair cells in the cochlea are dead, hearing loss will be severe or profound; if the hair cells are damaged but still functioning to some level, hearing loss may be variably more mild.
Now you know about how ears work, it may help to know some of the facts All About Sound…