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The Ear: Audition

Ψ  Sound waves have;
     Loudness (Amplitude)
     Pitch (Frequency)
Ψ  Measuring sound waves
    A decibel is a relative measurement of the intensity of a sound wave. A quiet whisper at 1 meter is about 10 decibels, noise from a motor car at 5 meters is about 70 decibels and noise from a large jet plane at 40 meters is about 110 decibels.
    Ψ  To many decibels for to long causes deafness.
Ψ  Outer ear:
     External ear - composed of the visible parts of the ear.
     Auditory canal - the canal leading to the eardrum.
     Tympanic membrane - the membrane in the ear that vibrates to sound.
     The Tympanic membrane is the eardrum!
 Ψ  Middle ear:
     Ossicles (AW-sick-culls) - three small bones articulated to each other in the middle ear: malleus(hammer), incus (anvil), & stapes (stirrup). They conduct the vibrations of the tympanic membrane to the inner ear.
     Oval window - end membrane
Ψ  Inner ear:
     Cochlea - the snail-shaped tube (in the inner ear coiled around the modiolus) where sound vibrations are converted into nerve impulses by the Organ of Corti
     The auditory receptors, called hair cells are bend by the basilar membrane generating nerve impulses.
     Auditory nerve
Ψ  Auditory brain areas
     Primary auditory cortex
     Auditory association area
Ψ  Auditory cues
     Calculating direction of a sound - timing difference between the ears.
     Calculating pitch - by Frequency & Place
     Calculating loudness - by rate of arrival of nerve impulses

General Psychology
Robert C. Gates