Transmission & Drivetrain Systems Flashcards
7 cards from real ABA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Transmission & Drivetrain Systems flashcards as text
What is the primary role of the ossicular chain in auditory transmission?
Answer: Impedance match the air-filled ear canal to the fluid-filled cochlea
The ossicular chain (malleus, incus, stapes) acts as a mechanical transformer that matches the low impedance of air to the high impedance of cochlear fluids.
The lever action of the ossicular chain contributes approximately how much gain in sound pressure?
Answer: 5.6 dB
The ossicular lever ratio (malleus arm to incus arm) provides approximately 1.3:1 mechanical advantage, contributing about 2 dB of the total middle ear gain.
Which structural feature of the tympanic membrane–stapes footplate area ratio contributes most to middle ear transformer gain?
Answer: Area ratio of tympanic membrane to stapes footplate (~17:1)
The ~17:1 area ratio between the tympanic membrane and stapes footplate concentrates force onto a smaller area, yielding approximately 25 dB of pressure gain.
Disruption of which ossicle most severely compromises the transmission 'drivetrain' if completely separated?
Answer: Incudo-stapedial joint
Separation at the incudo-stapedial joint breaks the ossicular chain entirely, causing a maximal conductive hearing loss of approximately 60 dB HL.
Bone conduction bypasses which component of the auditory transmission drivetrain?
Answer: The outer and middle ear
Bone conduction transmits vibration directly through the skull to the cochlea, bypassing the outer ear canal and middle ear mechanics.
What phenomenon explains why the acoustic reflex stiffens the ossicular chain during loud sounds?
Answer: Tensor tympani and stapedius muscle contraction
The stapedius (primarily) and tensor tympani muscles contract reflexively, stiffening the ossicular chain and reducing low-frequency transmission to protect the cochlea.
Otosclerosis primarily impairs transmission by affecting which part of the ossicular drivetrain?
Answer: Bony fixation of the stapes footplate in the oval window
Otosclerosis is characterized by abnormal bone remodeling that fixes the stapes footplate, preventing its piston-like motion and causing conductive hearing loss.