The ear and how we hear

Sound

Sound waves are invisible vibrations travelling in all directions from a sound source. The range of different sound waves in any given environment is a ‘soundscape’.

Sound waves can be generated in our voice box and projected from our mouths, enabling us to express our thoughts through speech. Devices such as speakers and musical instruments are also specifically designed to generate sound waves.

Sound waves are also generated by elements and objects interacting in the environment around us (e.g. waves crashing on rocks, boots crunching on gravel, car tyres spinning along roads, wind rustling leaves, machine mechanics, etc).

Almost all sound waves are unique, reflecting the vast range of different sounds. Sound waves vary in frequency (pitch), amplitude, pressure/intensity, speed and direction.

Parts of the ear

Our ears are a highly complex system of canals, membranes, bones, fluid, cells and nerves that receive and amplify sound waves, convert sound waves into ‘electric’ impulses and transmit it to the brain to be processed and perceived as sound.

The ear is categorised in three main ‘parts’:

  • Outer ear: visible skin and cartilage outside our heads (pinna) and the ear canal
  • Middle ear: ear drum and ossicles (three smallest bones in the human body – malleus, incus and stapes)
  • Inner ear: cochlea – small spiral shaped organ filled with fluid and hair cells (cilia) – and the nerve running from the cochlea to the brain

How the ear hears

  1. Sound waves are collected in the pinna, travel along the ear canal and vibrate the ear drum
  2. Ear drum vibrations move the chain of 3 small bones, one of which is connected to the cochlea
  3. The cochlea is filled with fluid and movement of the 3 small bones moves the fluid in the cochlea
  4. Moving fluid stimulates hair cells lining the cochlea, which transforms sound into electric signals
  5. Electric signals are transmitted along to the auditory nerve to the brain
  6. The brain processes, perceives and gives meaning to sound – see How we process sound for more information

This complex system operates instantaneously and can process multiple soundwaves at once.

Find out more about Mackay Hearing at mackayhearing.com.au or call 4952 4649.

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