How the ear works
Webpage published: 2011
We explain how the human ear works, with clear images and diagrams, and links to useful videos and hearing loss simulators:
Different levels of hearing were first noticed at the close of World War II by Dr Ramsdell while he was working in Deshon Army Hospital in Butler, Pennsylvania, which was a veteran’s Administration Hospital.
He had the opportunity to observe young adults who had lost some or all of their hearing whilst on active service, and recognised the four stages of how we use our hearing, particularly the importance of the ‘feeling of oneness with an active environment’. These young adults constantly complained that the world seemed dead.
Ramsdell became aware that we rely on our hearing for:
- understanding speech – the symbolic level. Informs, educates and entertains.
- appreciating sounds that please us – the aesthetic level. Gives pleasure.
- recognising sounds that alert us – the warning level. Alerts and prepares.
- recognising the changing background sounds of the world around us – the primitive level. Auditory background for daily living.
How does this work in practice?
You are sitting in a room near an open window which looks out onto a busy road. The sound of traffic is comforting or irritating depending your your reaction to the noise. All the same you know you can hear it. Primitive level.
You remember that you have forgotten something for a meal you are making and you decide to drive to a local shop. You listen to the car radio which tells you that the traffic is heavy on the main road. Sure enough, the noise of the traffic is louder as you approach. The spoken word and the background sound mean the same thing – heavy traffic. Symbolic level.
You hear a siren and know that you will need to pull over and wait for the emergency vehicle to pass. This is because the sound of the siren has alerted you and given you an instruction. Warning level.
We have two ears so that we can hear sound all around us. Hearing is very complicated and made up of several important parts of the body joined together. If one link of a chain is broken, the whole chain is affected. If one part of the ear doesn’t work properly, the hearing is affected.
The ear is divided into three sections:
- The outer ear consisting of the pinna, ear canal and eardrum
- The middle ear consisting of the ossicles and ear drum
- The inner ear consisting of the cochlea, the auditory (hearing) nerve and the brain
People who have problems with the outer and middle ear have conductive deafness. People who have problems with the inner ear have sensorineural hearing loss.
Conductive deafness can be caused by things such as an ear infection, a hole in the eardrum or otosclerosis. Sensorineural hearing loss can be caused by things such as old age, Ménière’s Disease or loud noise. Many kinds of conductive deafness can be cured. Most kinds of sensorineural hearing loss cannot be cured.
Different types of hearing loss
Very few people who have a hearing loss hear nothing at all. Many people who are hard of hearing or deaf hear some sounds. What varies from person to person, is how much they hear. It is confusing for both deaf and hearing people. The deaf person thinks they have heard what the hearing person said and answers accordingly. If the deaf person misheard, their answers make no sense to the hearing person and both become increasingly frustrated as the conversation goes on. More on communication.
A conductive hearing loss makes everything sound the same, just much quieter whereas sensorineural deafness causes speech to sound quieter and distorted. Consonant sounds are high frequency sounds whereas vowels are low frequency.
- To a hearing person sound is loud and clear in all areas of the speech spectrum, it would sound like this:
- Someone with presbyacusis (old age deafness) would hear the vowels in speech but not the consonants, so speech might sound like this:
- To someone with Ménière’s Disease where the low frequency sounds are affected, the person would not hear the vowels, it might sound like this:
- To someone with a perforated eardrum with a conductive hearing loss the volume of speech is affected rather than the clarity, it might sound like this:
Please visit Better Hearing Institute hearing loss simulator which gives a fascinating insight of hearing loss for your hearing family and friends. The simulator allows you to play different sound examples and compare them for normal hearing, a mild hearing loss and a moderate hearing loss.