Book Definition: Sound waves are transduced into neural messages in the cochlea, which is the primary organ of hearing, then sensation and perception occur so that you interpret the stimulation as a sound.

In Your Own Words

  • The ability to recognize sounds around you.
  • To understand certain sounds.


Frequency - the number of cycles completed by a wave in a given amount of time (usually a second).

Amplitude - the physical strength of a wave.
  • Usually measured form peak (top) to valley (bottom), on a graph of the wave.

Cochlea- primary organ of hearing.

Basilar Membrane- the strip of tissue sensitive to vibrations in the cochlea.

How Do We Distinguish One Sound From Another?

  • All sounds have a different pitch and loudness; they sound distinctively different because of the odd mixtures of tones every sound carries (called timbre).
  • Most natural waves are mixtures of tones instead of pure tones.
  • This complex quality of sound enables us to recognize a friends voice from someone else, to the same songs covered by different artists.

How do we hear sound waves?

1. Airborne sound waves must be relayed in the inner ear, and strike the tympanic membrane (eardrum).
2. The cochlea (an organ in your ear - a coiled tube in the inner ear where sound waves are transduced into nerve message) focuses the vibrations on the basilar membrane.
3. The basilar membrane converts the vibrations into neural messages with micro-hairs that are excited with sound waves.
4. The neural messages travel to the auditory cortex in the brain.

Disabilities associated with hearing

  • Deafness is the inability to experience the sensation of sound. There are two types: Conduction Deafness and Nerve Deafness.
    • Conductive Deafness- Becoming deaf due to a physical trauma (Example: the first book of The Hunger Games when Katniss is close to a loud explosion and she loses hearing in one ear)
    • Nerve Deafness- When the nerves you use for hearing just don't work


  • On transformers,as they analyze the sound waves the robots use to hack the government's firewall, their screen shows all of the individual frequencies and tones which exist in that one sound. Go watch transformers (the first one)
  • Students can hear the fire alarm at the school, knowing to evacuate. The fire alarm has a high amplitude because it is loud. The recorded-voice telling people in the school building to evacuate has a specific pitch, determined by its frequency.
  • Listening to a friend, teacher, song etc. and your ears are able to pick up these waves, and your brain transduces them into information your brain can recognize.
    ear anatomy diagram
    ear anatomy diagram