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Unformatted text preview: Next sense…Hearing
Sound Movement of air molecules from a source of vibration Frequency- (pitch) the rate at which waves vibrate measured
Frequencyas cycles/sec (Hz)
Amplitude (loudness)- the intensity of sound, measured in dB
Complexity (timbre)- mixture of frequencies, can be simple
or complex, difference in sound btw a violin and trumpet
or Outer Ear- The pinna
Outer Sound arrives outer ear
Catches sound waves
Outer ear funnels in
sound to eardrum
Eardrum Vibrates when sound
waves hit Miniature drum
Tympanic Membrane Middle Ear
Middle Vibrating eardrum
causes the 3 ossicles to
Hammer, anvil, &
Amplify and convey
vibrations to oval
Ossicles In Latin “malleus, incus, and stapes” translated the hammer, the anvil, and the stirrup. The malleus articulates with the incus and is
attached to tympanic membrane
The incus is connected to both the other bones.
The stapes articulates w/ incus and is attached
to the oval window or opening btw middle ear
and the vestibule of the inner ear. Inner Ear
electrical Transmitted to
brain Cochlea Cochlea
Cochlea The auditory hair cells
sit within the organ of
Inner hair cells-the
auditory receptors in
Outer hair cells- help
to "tune" the cochlea and
provide support Basilar Membrane
Basilar Basilar membrane bounces up and down stereocilia are sheared
back and forth under the tectorial membrane.
When stereocilia are pulled, the hair cell depolarizes.
This signal is transmitted to the auditory nerve to the brainstem.
This Basilar membrane
Basilar The basilar membrane is actually thinner and
narrower at the base of the cochlea than at the
High frequencies vibrate at the base of the
cochlea and to low frequencies at the apex.
It is the properties of the basilar membrane
that set up this gradient, not the properties of
the hair cells.
Tonotopic Superior Olive
Superior The ventral cochlear nucleus cells then project
to a collection of nuclei in the medulla called
the superior olive.
Where differences timing and loudness of the
sound in each ear are compared
Helps determine the direction the sound came
Interaural Time differences Binaural Cues
Interaural Time Difference (ITD)- biological
binaural cue is the split-second delay between
the time when sound from a single source
reaches the near ear and when it reaches the
Interaural Amplitude (intensity) Difference
(IAD)(IAD)Sound amplitude and pressure differences
between each ear
between Auditory (Vestibular) Pathway
Auditory Hair cells → spiral ganglion. → cochlear nerve
→ vestibulocholear nerve → medulla oblongata (superior
olive) → inferior colliculus (midbrain) → thalamus →
auditory cortex Purpose is to keep tabs on position/motion of head in space. detect rotation, shake or nod your head (angular acceleration).
detect motion along a line - elevator drops, lean body (linear
acceleration 3 semicircular canals detect angular acceleration in 3 mvnt
dimensions, each canal detects motion in a single plane
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- Spring '10