The Ear and Its Response Loudness

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The Ear and Its Response Loudness

• Mary Anne Galioto
• March 2, 2001

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Introduction

• The study of the ear is called Otology
• this includes the anatomy (structures and how it
  works)
• understanding hearing such as loudness, pitch and
  tone
• problems and disorders that can occur to the ear.
  

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Anatomy

• Three main parts to the ear
• External
• Middle
• Inner

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External Ear

• Auricle or called the pinna,
• cartilaginous curved part of the ear
• Outer auditory canal.
• tubular passageway that is lined with delicate
  hairs and small glands that produce a wax-like
  secretion.
• Eardrum
• A thin membrane that separates the outer ear from
  the middle ear

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Middle Ear

• Eustachian tube
• keeps the eardrum intact by equalizing the
  pressure between the middle and outer ear.
• Chain of three ossicles, or very small bones.
• malleus (hammer)
• is partly embedded in the eardrum
• incus (anvil)
• stapes (stirrup)
• fits into the oval window, a membrane that fronts
  the inner ear.

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Inner Ear

• The inner ear has organs for hearing and balance.
• Three main structures
• Cochlea
• coiled tube that is divided into three
  fluid-filled canals
• spiral-shaped organ called the Corti
• receive sound vibrations from the middle ear and
  sends them on to the brain via the auditory
  nerve.
• Vestibule
• it helps maintain balance and orientation by
  monitoring the sensations of movement and
  position
• hairlike projections embedded in gelatin have
  small mineral particles. Depending on the
  position of the head, the gelatin and mineral
  particles exert varying pressures on the sensory
  cells.
• Three semicircular canals
• Direct body balance when the body moves in a
  straight line or rotates in any direction.

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How do all of the parts of the eat fit together?

• Outer Ear
• sound vibrations are collected by the pinna and
  proceed through the outer auditory canal, it then
  leads to the eardrum
• Middle Ear
• Vibrations of the eardrum move the hammer, and
  this moves the anvil, which moves the stirrup. As
  the sound vibrations pass through the chain of
  bones, which is a smaller area, there force is
  concentrated. This amplifies the sound just
  before it passes through the oval window and into
  the inner ear.
• Inner Ear
• The sensory cells in the Courti have thousands of
  hairlike projections that receive sound
  vibrations from the middle ear and sends them on
  to the brain via the auditory nerve. In the brain
  they are recognized and interpreted as specific
  sounds.

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Loudness, Pitch, and Tone

• Loudness
• the human ear is capable of perceiving a wide
  range of loudness
• sound is measured in decibels
• Pitch
• Is related to the sounds vibration frequency or
  the number of sound waves passing into the ear in
  a given period.
• The greater the frequency the higher the pitch.
• Tone
• This ability enables humans to distinguish
  between two people singing the same note.

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Disorders

• There are many disorders that can occur in the
  human ear.
• The common ones
• hearing loss
• there is a variety of causes of hearing loss and
  places in the ear where these can occur
• ear infections
• swimmers ear and childhood ear infections are
  common
• balance disorders
• if one sensory organ is not working correctly
  this could occur

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How does Physics fit into all this?

• Pressure in the Eustachian tube
• Sound waves that the ear picks up on (decibels)
• The inner ear with its gelatin and mineral
  particles, without the earths gravity we would
  have no balance or equilibrium.