An Introduction to Hearing
Sound waves enter the outer ear and cause the eardrum to vibrate. These vibrations pass along the middle ear via three small bones known as the ossicles. The ossicles amplify the vibrations and transmit them on to cochlea (coiled, fluid-filled spiral tube) in the inner ear. Hair cells in the cochlea move in response to the vibrations and send electrical signals along the auditory nerve to the brain.
Hearing loss is a common problem and it is estimated that there are more than 10 million people (1 in 6) in the UK with some degree of hearing loss. It often develops with age but can be caused by repeated exposure to loud sounds, infections of the ear, illness and trauma. Hearing loss can occur suddenly but usually develops gradually. Signs of hearing loss can include: difficulty hearing clearly and misunderstanding phrases, asking for repletion, listening to music or watching television with the volume turned up higher than other people require.
Hearing loss is the result of sounds not reaching the brain. There are two main types of hearing loss, depending on where the problem lies.
- Conductive hearing loss: when sounds are unable to pass from the outer or middle ear to the inner ear. This may be due to a blockage due to wax, congestion or a perforated ear drum or disorder of the ossicles.
- Sensorineural hearing loss: caused by damage to the hair cells inside the cochea or damage to the auditory nerve. This may occur naturally with age or as a result of an injury.
- Mixed hearing loss: Combination of a conductive and sensorineural element.
- Central hearing loss: Condition which affects the brain’s ability to process auditory information.
Treating hearing loss
Hearing loss is treated depending on the underlying cause if the condition. Hearing loss due to a conductive problem is often temporary and treatable. For example, earwax build-up can be removed by drops, syringe or microsuction. Hearing loss caused by infections can be treated with antibiotics. Surgery may be an option to drain a build-up of fluid, repairing a perforation or correct problems with the ossicles.
However, a sensorineural hearing loss is permanent and there are several options including hearing aids, implants and the use of lip reading and/or sign language.