ABA Transmission & Drivetrain Systems 2

Question 1

What is the primary role of the ossicular chain in auditory transmission?

Accepted Answer

Impedance match the air-filled ear canal to the fluid-filled cochlea

Answer

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.

Question 2

The lever action of the ossicular chain contributes approximately how much gain in sound pressure?

Accepted Answer

5.6 dB

Answer

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.

Question 3

Which structural feature of the tympanic membrane–stapes footplate area ratio contributes most to middle ear transformer gain?

Accepted Answer

Area ratio of tympanic membrane to stapes footplate (~17:1)

Answer

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.

Question 4

Disruption of which ossicle most severely compromises the transmission 'drivetrain' if completely separated?

Accepted Answer

Incudo-stapedial joint

Answer

Separation at the incudo-stapedial joint breaks the ossicular chain entirely, causing a maximal conductive hearing loss of approximately 60 dB HL.

Question 5

Bone conduction bypasses which component of the auditory transmission drivetrain?

Accepted Answer

The outer and middle ear

Answer

Bone conduction transmits vibration directly through the skull to the cochlea, bypassing the outer ear canal and middle ear mechanics.

(ABA) American Board of Audiology Practice Test

(ABA) American Board of Audiology Practice Test

ABA Transmission & Drivetrain Systems 2