PDC Test - The Ear
You can earn 0.25 PDC by passing the exam following this article, which has been approved for publication by NCRA's Council of the Academy of Professional Reporters.
The questions are based on the material in the article but some may require additional research. Send your answer sheet to NCRA's Continuing Education Office, 8224 Old Courthouse Road, Vienna, VA 22182, and enclose a check for $40 (member) or $50 (non-member) to cover the processing fee.
Have you ever tried to carry on a conversation near the center of a big city during the rush hour? If so, you can remember the continuous din of elevated trains, police whistles and taxi horns, shouts of newsboys, and the clacking of shoes on sidewalks.
The sounds you hear are what the special organs of hearing are able to translate from the vibrations in the air about you. The vibrations may be produced by an air hammer tearing up pavement, by metal clanging against metal in a bell, or by a musician blowing on the reed of a saxophone. The more vibrations per second, the higher the frequency, or pitch. Loudness is a measure of intensity, or power, of the vibrations.
Most people can hear sounds between about 40 cycles, or vibrations, per second and 20,000 per second. How do sounds that begin as air vibrations reach the part of the brain that identifies and catalogs them? The vibrations travel down the tube leading from the outer ear to the eardrum. The tube is called the external auditory canal. It is lined with hair and glands that secrete ear wax. The tube is funnel-shaped to help collect sound waves and guide them to the eardrum, or tympanic membrane.
On the inner side of the tympanic membrane is the middle ear, which contains three tiny bones, or ossicles. The bones, called the hammer, anvil, and stirrup, are stretched across the cavity of the middle ear to relay the vibrations from the eardrum to the fluid-filled cavity of the inner ear. Sound waves vibrate the eardrum and the hammer attached to it. The hammer pushes the anvil, which, in turn, moves the stirrup.
The stirrup acts as a piston on the membrane of the oval window as it pushes against the fluid in the inner ear. The inner ear contains the cochlea, a snail-shaped spiral tunnel in which the organ of Corti -- the true organ of hearing -- is located. The inner ear also contains the semicircular canals, which help give us our sense of balance. The organ of Corti consists of specialized nerve cells that follow the spiral of the cochlea. The cells rest on the basilar membrane, which is made up of connective-tissue fibers. The nerve cells have hairlike projections and the tips of the hairs are in contact with a membrane above, the tectorial membrane. The spongy bone that forms the core of the cochlea has many tiny tunnels through which the nerves from the specialized cells carry impulses to the brain.
Each middle ear is connected with the throat in back of the mouth by a passageway called the auditory, or eustachian, tube. The job of this tube is to equalize air pressure in the middle ear with the atmospheric pressure.
The organ of equilibrium, or balance, has two kinds of nerve receptors. They are located in three membrane-like tubes, called semicircular canals, and two small sacs in the inner ear next to the cochlea. The semicircular canals are set at right tangles to each other -- like the top and adjacent sides of the corner of a box. The nerve receptors in the semicircular canals are hair cells with the tips of the hairs embedded in a plume of gelatin-like material. When the head is moved, the fluid flows against the plumes, called cristae. This pressure triggers the receptors, which transmit to the brain the message that the head is changing position. The second kind of receptor is located in the two small sacs. It also uses hair cells with the hairs embedded in a gelatin-like material. But the surface of the gelatinous mass in the two sacs is coated with a layer of tiny grains of limestone. Movement of the head causes the grains, called otoliths, to shift. This causes the hair cells to send out nerve impulses. This article and the accompanying tests were prepared by Nancy Patterson, who has served on various committees and boards for NCRA and is the winner of the 1990 DSA award. Nancy is the director of Bryan College of Court Reporting in Los Angeles, California. The article "The Ear" is reprinted by permission of the American Medical Association from The Human Machine, copyright 1979.
Test for "The Ear"
1.Nerve receptors for the balance system are located in the
A. auditory canal
B. eustachian tube
C. semicircular canals
D. middle ear
2. Moving your head causes the shifting of tiny grains of limestone called what?
3. The eustachian tube connects the throat with the
A. inner ear
B. middle ear
4. The eardrum is also called the
A. tympanic membrane
B. semicircular canal
5. Tinnitus is
A. inflammation of the middle ear
B. inflammation of the inner ear
C. ringing in the ear
D. bone conduction
6. The true organ of hearing is located in the
A. eustachian tube
D. semicircular canals
7. Which is not an ossicle?
8. The auditory nerve is which cranial nerve?
9. The auditory nerve has two branches, the cochlear nerve and the
10. Cerumen is secreted by the walls of the
B. external auditory canal
C. eustachian tube
11. The external auditory canal is also known as the external acoustic
12. The membrane-covered opening in the wall between the middle and inner ear is called the
A. ossa terminalis
B. os magnum
C. fenestra ovalis
D. eustachian valve
13. Two small sacs next to the cochlea help determine
A. high tones
B. low tones
14. Hairlike projections of nerve cells in the organ of Corti are in contact with the
A. tectorial membrane
B. pectorial membrane
C. tympanic membrane
D. malleolar membrane
15. The root ``os'' means bone and also
16. Another name for the auricle is the
17. The canal which extends from the auricle to the eardrum is called the
18. Fluid fills the cavity of the
A. inner ear
B. middle ear
C. eustachian tube
19. The cochlea is a spiral shaped tunnel in what bone?
20. The specialized nerve cells of the cochlea rest on what membrane?
21. Atmospheric pressure is equalized through the
A. eustachian tube
B. cochlear membrane
C. semicircular canal
D. oval window
22. Which bone is attached to the oval window?
23. The root ``lith'' means
24. The root '`laryng'' in ``otolaryn-gologist'' means
25. The word ``decibel'' means
A. one tenth of normal hearing
B. ten times normal hearing
C. the intensity of an average bell
D. the unit of measurement of acoustic power
|Answer Sheet for "The Ear"
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