Outer ear functions
the pinna
What is the pinna made up of (except the lobule)?
Skin covered cartilage (except lobule)
What is azimuth?
Direction (in this context the angle of the sound source)
Can the middle ear be seen from the outside? (without any tools etc.)
NO
Is the ossicular chain in the outer ear, middle ear, or inner ear?
Middle ear
What are the 3 main functions of the outer ear?
Amplification, localization, protection
What is the volume of the external auditory canal?
1.4cc
What does directional function measure?
localization and distance estimation.
What does the eustachian tube connect?
the middle ear to the nasopharynx
How is the ossicular chain suspended?
By ligaments, the bones are attached to each other but not directly attached by any other bones
What is cerumen?
ear wax!
What is the term for the "ring" outlining the pinna?
helix.
What is interaural time difference?
time delay (phase difference) between sounds arriving at the left and right ears.
What is the lateral wall of the middle ear?
the tympanic membrane.
2 parts:
1) What type of joint articulates the malleus and incus?
2) How does the incus articulate with the stapes?
1) saddle joint (type of synovial joint)
2) ball and socket joint
the tympanic membrane
What is the difference between the external auditory canal of adults versus children?
Adult EAC has an isthmus that causes it to bend. For an otoscopic exam, adult ears can be pulled upward and backward. A child's EAC is more straight, so for an otoscopic exam, the ear is pulled more horizontally.
What are the functions of the middle ear?
impedance matching, selective oval window, pressure equalization
How long is the stapedius (middle ear muscle)?
6mm long, smallest muscle in the human body!
What is the resonance amplification of the concha and the external auditory canal?
Concha ~5kHz resonance
External auditory canal ~2.5kHz resonance
What is a genetic feature that can appear on the pinna as a result of human evolution?
Auricular (darwin's) tubercule.
When does a sound shadow occur?
When the wavelength is less than the head size. (interaural intensity difference)
What are the parts of the temporal bone?
Squamous part
Mastoid part
Tympanic part
Styloid process
Petrous part
What is the ossicular chain made up of?
the malleus (hammer), the incus (anvil), and the stapes (stirrup)