Hearing

Hearing is one of the five senses. Ears detect vibrations in the air. These vibrations are sounds. Most animals can hear. Most land vertebrates hear through ears. Fish hear in several different ways. Many use their swim bladder to hear, and many use their lateral line.

In mammals, sound travels through three main parts of the ear to be heard. These are the outer, middle and inner ear.

• Outer Ear - This is the part of the ear that we can see called the pinna as well as the inside of the ear called the ear canal. Sound first travels through the pinna and ear canal then to the eardrum at the end of the canal which the sound makes vibrate.
• Middle Ear - Sound continues to travel deeper into the ear and is helped by three of the smallest bones in the body - hammer, anvil and stirrup - to reach the inner ear.
• Inner Ear - Here the sound reaches a small tube shaped like a snail shell, called the cochlea. Inside the cochlea is a fluid, which moves tiny hairs that send signals to the brain which interprets sounds for you to understand and hear

Hearing Media

• This animated video illustrates how sounds travel to the inner ear, and then to the brain, where they are interpreted and understood. The cochlea in the inner ear is a spiral-shaped organ that contains hair cells, which sense sound vibrations. Hair cells convert sound vibrations into chemical signals that the auditory nerve can understand.

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  Schematic diagram of the human ear

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  The middle ear uses three tiny bones, the malleus, the incus, and the stapes, to convey vibrations from the eardrum to the inner ear.

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  The inner ear is a small but very complex organ.

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  The lateral lemnisci (red) connects lower brainstem auditory nuclei to the inferior colliculus in the midbrain.

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  A cat can hear high-frequency sounds up to two octaves higher than a human.