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What is Audition?
 Hearing
What sounds do we hear the best?
 Sounds
with the frequencies in the range corresponding
to the human voice.
How Sounds Travel to the Ear
A sound
Stimulus Energy
Molecules of Air bump into the next molecules
waves of compressed & expanded air
Ears detect the air pressure change
The vibrations are felt
Ears transform the vibrating air
Sound Waves
Strength of the sound waves
 Loudness
The number of wavelength that pass a point in a given time
which determines the pitch
A tone’s experienced high or lowness
How sounds are measured
 The absolute threshold for hearing is arbitrarily
Structure of the Ear
The ear is divided into the outer, middle & inner ear.
Outer Ear
Auditory Canal
 Channel
that sounds
 Waves first pass
Eardrum #8 A tight membrane that
vibrates with the waves
Middle Ear
Bones of the middle ear = the Hammer #1,
Anvil #2, Stirrup #3 which vibrate with the
Semicircular Canals #4
Inner Ear
Oval window = where the stirrup connects
to the cochlea. #9
Cochlea = a coiled, bony, fluid-filled tube in the
inner ear through which sound waves trigger nerve
impulses. #6
Perceiving Loudness
Basilar membrane’s hair cells
Cochlea and Loud Sounds
Auditory nerve = nerve which sends the auditory
message to the brain via the thalamus. #5
Eustachian Tube #11
The eustachian tube connects the middle ear to the
Its purpose is to equalize middle ear pressure with
environmental pressure. When your ear "pops" on a
high-speed elevator or in an airplane, the reason is
that the eustachian tube has opened and equalized
Neural Impulse to the Brain
Place Theory
The theory that links the pitch we hear with the
place where the cochlea’s membrane is
Frequency Theory
The theory that the rate of nerve impulses
traveling up the auditory nerve matches the
frequency of a tone, thus enabling us to sense
its pitch.
Hearing Loss
Conduction Hearing Loss
Hearing loss caused by damage to the
mechanical system that conducts sound
waves to the cochlea.
Problems with the eardrum or three bones of
the middle ear.
Sensorineural Hearing Loss
Hearing loss caused by damage to the
cochlea’s receptor cells or to the auditory
nerves; also called nerve deafness.