the-ear-and-hearing-sense

The human ear is amazing! It is an organ which is so finely tuned and works really cleverly to allow us to enjoy sounds and conversations around us.  Really, if you think about it…the ear connects us with people. If we can’t hear, we can’t find out about our partner’s day, hear the grandchildren excitedly sharing their school news or enjoy a TV program. Like any part of the body, we need to look after it and if something starts to go wrong, take action sooner rather than later.

But first, let’s go through how the ear actually works.

The ear is made up of 3 very important parts:

  1. The outer ear
  2. The middle ear
  3. The inner ear

Each part has a specific role in making the sound we hear meaningful. For example, picking up the pitch of the bird in the tree and transmitting it all the way to the brain where you can recognise it as ….a hummingbird.

The outer ear

The outer ear basically is the part of the ear we can see. The physical ear as we know it is called the pinna and the ear canal is the opening into which the sound travels.

The bowl shape of the ear is actually designed to pick up sounds from in front of us rather than behind us. So, when we go into a very noisy restaurant, the ear naturally tries to stop the background noise from behind us and focus on the person in front of us. Also, the pinna lets us know which direction a sound is coming from which is really important especially in traffic or outside.

The ear canal is made up of 2/3 cartilage and 1/3 bone and acts as a channel to let the sound pass through to the eardrum.

outer-ear-2

The middle ear

The middle ear is basically a vibrator.

Depending on the loudness and pitch of the sound, the vibrations vibrate differently to tune into this.

The eardrum is piece of skin which moves with the sound in the ear canal. For example, if it is a loud sound, the eardrum movement is big and if it is a soft sound, the eardrum moves quite gently. If the sound is high pitched like a flute, then the eardrum moves very quickly or if it is a low pitched sound like a drum, then the eardrum moves slowly.

The sound is then passed onto the three middle ear bones, the malleus, incus and stapes. These three bones all vibrate onto a small membrane leading to the inner ear called the oval window.

middle-ear

The inner ear

The inner ear is called the cochlea and is shaped like a snail shell. The cochlea is filled with fluid and this fluid bathes the millions of tiny hair cells attached to the walls.

As the sound is passed on from the outer and middle ear, a big wave of fluid moves along the cochlea and bend the hair cells. If you can imagine a wave in the sea moving the seaweed underneath, this is pretty much how it works. This wave stimulates the tiny hair cells to create an electrical impulse which is then passed onto the nerve of hearing.

So how does the inner ear work out what pitch and volume the sound is? Again it is pretty amazing.

inner-ear

Remembering that the cochlear looks like a snail shell – all the hair cells at the start of the snail shell are coded as high pitched hair cells, the middle of the shell is coded as mid-pitched cells and all the cells at the end of the snail shell are coded as low pitched cells. So if you are listening to a bass guitar, the wave of fluid washes all the way to the bottom of the cochlea to stimulate the low pitched hairs.

Just imagine how complex this is when listening to speech sounds or music which have a huge variety of low and mid pitched sounds? Its is just incredible.

The last part of the chain involves  nerve fibres which sit underneath the hair cells. These nerve pass the message through the auditory nerve to the hearing part of the brain called the auditory cortex.

The brain then uses our memory and our knowledge as well as all our senses to make that sound meaningful. Just like when you hear a nursery rhyme from your childhood, it can bring back many memories and feelings associated with it.

See this helpful video which shows how we hear:

How we hear video

Our hearing connects us

Our hearing connects us with life:

  1. Our hearing keeps us safe  – e.g. Awareness of ambulance approaching
  2. Our hearing keeps us connected with never-to-be-repeated moments – e.g.. The wedding vows
  3. Our hearing keeps us connected to people, especially our loved ones – e.g. Grandchild whispering  that they love you
  4. Our hearing keeps us doing things we enjoy – e.g. Going to the theatre
  5. Our hearing keeps us effective in our work – e.g. The GP hearing precisely what the ailment is from his patient
  6. Our hearing keeps us connected to the environment  e.g. Hearing the birds in the trees and rain on the roof

It is so important to treat your hearing like a precious gift and act sooner rather than later if you notice a problem. See Act sooner rather than later.