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CD 351 Exam #2 questions with verified answers rated A+
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CD 351 Exam #2 questions with verified answers rated A+
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CD 351 Exam #2What are the 3 sections the ear is made up of? - correct answer ✔✔1. outer
2. middle
3. inner
What is the frequency range that humans can hear? - correct answer ✔✔20 Hz to 20,000Hz (though only
infants can hear 20,000Hz)
What are the two parts of the outer ear? - correct answer ✔✔1. pinna
2. external auditory meatus
Describe the Pinna - correct answer ✔✔⚫the flap-like structure attached to the head
⚫it captures sound and directs it to the middle ear
⚫composed of fibrocartilage that is covered by skin
⚫attached to the temporal bone by extrinsic muscles and ligament
What are the 6 parts of the pinna? - correct answer ✔✔(uneven and filled w/ pits)
1. concha: deepest depression
2. helix: the rim
3. antihelix: semicircular ridge anterior to the helix
4. tragus:Flap partially covering the entrance to the ear canal
5. antitragus: smaller flap opposite the tragus
6. ear-lobe: non-cartilaginous, highly vascular
Describe the external auditory meatus (ear canal) - correct answer ✔✔⚫an oval, S-shaped
⚫25-35mm (1in) long & 6-8 mm in diameter
⚫the lateral (outermost) third is cartilage and is continuous w/ the cartilage of the pinna
,⚫The medial 2/3rd is composed of bone and contain cilia and glands that produce cerumen (wax and
oils). Cerumen keeps the meatus clean and supple and prevents foreign bodies like insects from entering
the canal
Describe the acoustic properties of the outer ear - correct answer ✔✔in addition to the outer ear,
though, the head has an impact on the sound intensity at the entrance to the ear canal
What is resonance of the outer ear? - correct answer ✔✔⚫objects have frequencies that they prefer to
vibrate at
⚫if you try to vibrate it at different frequencies, the vibrations will be dampened and eventually die out
⚫if you try to vibrate it at its preferred frequency, the vibrations will be reinforced and the object will
resonate
Examples of resonance - correct answer ✔✔⚫the note you get when you blow into a half-full beer
bottle
⚫when a garbage truck makes the windows rattle in a house
How to determine resonance... - correct answer ✔✔⚫the external auditory meatus is a half open tube
⚫The preferred resonant frequencies for a half‐open tube will be all those frequencies (call them A)
such that:
-the length of the tube is 1/4 the wavelength of A
⚫we can apply these principals to the external auditory meatus & determine its preferred resonance
- the EAM is approx. 2.3 cm
- so, the preferred resonate frequency will be 4 x 2.3
which equals 9.2 cm -this is the wavelength of the
sound and it corresponds to a frequency of about
3800 Hz
Are consonant higher or lower frequency sounds? - correct answer ✔✔higher
Describe the tympanic membrane - correct answer ✔✔⚫ also known as the eardrum
, ⚫ very thin, resilient membrane
⚫ it vibrates in response to acoustic energy
⚫approx 10mm (less than 1/2 in) in diameter, roughly circular in shape
⚫ has a thickened outer ring called the annunlus which is attached to a groove in the tympanic cavity
⚫ cone of light: can be seen from a central depression (umbo) - light reflected from the octoscope
What are the three layers of the tympanic membrane? - correct answer ✔✔1. outer layer: thin layer
continuous w/ the lining of the external auditory meatus
2. middle layer: fibrous layer; composed of circular and radial fibers; not present at the superior border -
creating pars flaccida (pars tensa is the rest of the TM)
3. internal layer: continuous w/ the lining of the middle ear cavity
Define tympanic cavity - correct answer ✔✔air filled cavity w/in the petrous portion of the temporal
bone `
What are the 3 categories of the tympanic membrane? - correct answer ✔✔1. epitympanic recess
2. contains the ossicles
3. specific landmarks
Describe the epitympanic recess - correct answer ✔✔⚫"attic"
⚫superior to the tympanic membrane
⚫ contains head of malleus and most of incus (bones of the middle ear)
What are the 3 ossicles of the tympanic mebrane? - correct answer ✔✔1. malleus
2. incus
3. stapes
List the 6 specific landmarks of the tympanic cavity. - correct answer ✔✔1. superior wall (tegmentum)
2. inferior wall (jugular)
3. lateral wall (membranous)
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