5.19 Human Hearing
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5.19.4 Binaural Directional Sensation
Our sense of the direction from which sound originates relies on how information
from one ear and the other determines a difference in (1) pulse time arrival; (2) the
beginning of a phase of the wave (for low frequencies); (3) intensity of a sound.
5.19.5 The Human Ear
Important parts of the human ear include (Fig. 5.16):
Auricle:
(‘Pinna’) The outer ear aids in collecting sound
Ear Canal:
The open passage from the outer ear to the ear drum
Ear Drum:
(‘Tympanic membrane’) is set in motion by an external
sound
Malleus:
(‘Hammer’) is the middle ear bone in contact with the ear
drum
Incus:
(‘Anvil’) is the middle ear bone between the malleus and
the stapes
Stapes:
(‘Stirrup’) is the bone which contacts the inner ear cochlea
window; the three middle ear bones match the impedance
of the ear drum to that of the oval window and liquid behind
Oval Window:
A membrane which transfers sound energy from the middle
to the inner ear
Round Window:
A membrane which allows the liquid in the inner ear ducts
to move in response to sound
Vestibule:
A chamber which holds balance organs (utricle and saccule); midway between the cochlea and the semi-circular
canals
Semi-circular canals: Three perpendicular fluid-filled semi-circular organelles in
the inner ear; the fluid moves in one or more canals when
the head accelerates, causing hair cells to stimulate nerve
cells
Cochlea:
An organelle in the inner ear which discriminates various
sound frequencies and their intensities, and sends this
information to the brain
Basilar Membrane:
Stiff membrane separating two liquid-filled ducts within
cochlea
Tectorial membrane: The vibratory membrane in the cochlea
Organ of Corti:
Auditory cells under the tectorial membrane with hairs to
sense vibration
Scala Vestibule:
A liquid-filled duct for sound transmission in the cochlea
from the oval window to the heliotrema, the end of the
cochlear spiral
159
5.19.4 Binaural Directional Sensation
Our sense of the direction from which sound originates relies on how information
from one ear and the other determines a difference in (1) pulse time arrival; (2) the
beginning of a phase of the wave (for low frequencies); (3) intensity of a sound.
5.19.5 The Human Ear
Important parts of the human ear include (Fig. 5.16):
Auricle:
(‘Pinna’) The outer ear aids in collecting sound
Ear Canal:
The open passage from the outer ear to the ear drum
Ear Drum:
(‘Tympanic membrane’) is set in motion by an external
sound
Malleus:
(‘Hammer’) is the middle ear bone in contact with the ear
drum
Incus:
(‘Anvil’) is the middle ear bone between the malleus and
the stapes
Stapes:
(‘Stirrup’) is the bone which contacts the inner ear cochlea
window; the three middle ear bones match the impedance
of the ear drum to that of the oval window and liquid behind
Oval Window:
A membrane which transfers sound energy from the middle
to the inner ear
Round Window:
A membrane which allows the liquid in the inner ear ducts
to move in response to sound
Vestibule:
A chamber which holds balance organs (utricle and saccule); midway between the cochlea and the semi-circular
canals
Semi-circular canals: Three perpendicular fluid-filled semi-circular organelles in
the inner ear; the fluid moves in one or more canals when
the head accelerates, causing hair cells to stimulate nerve
cells
Cochlea:
An organelle in the inner ear which discriminates various
sound frequencies and their intensities, and sends this
information to the brain
Basilar Membrane:
Stiff membrane separating two liquid-filled ducts within
cochlea
Tectorial membrane: The vibratory membrane in the cochlea
Organ of Corti:
Auditory cells under the tectorial membrane with hairs to
sense vibration
Scala Vestibule:
A liquid-filled duct for sound transmission in the cochlea
from the oval window to the heliotrema, the end of the
cochlear spiral