ABA Transmission & Drivetrain Systems 3

Question 1

In tympanometry, a Type Ad (deep) tympanogram pattern most likely indicates which transmission problem?

Accepted Answer

Ossicular discontinuity or hypermobile tympanic membrane

Answer

A Type Ad tympanogram shows abnormally high compliance (deep peak), indicating a highly mobile system such as ossicular discontinuity or a flaccid tympanic membrane.

Question 2

Which frequency range is most attenuated by the acoustic reflex's stiffening effect on the ossicular chain?

Accepted Answer

Low frequencies (<1000 Hz)

Answer

The stiffness introduced by acoustic reflex contraction primarily attenuates low-frequency transmission because stiffness reactance is dominant at lower frequencies.

Question 3

The Carhart notch, a characteristic audiometric dip around 2000 Hz on bone conduction, is associated with which drivetrain pathology?

Accepted Answer

Otosclerosis

Answer

The Carhart notch is a mechanical artifact of otosclerosis where stapes fixation reduces the resonant contribution of the ossicular chain to bone conduction testing.

Question 4

What is the approximate total middle ear transformer gain that compensates for the impedance mismatch at the air-fluid interface?

Accepted Answer

25–30 dB

Answer

The combined area ratio and ossicular lever action provides approximately 25–30 dB of gain, offsetting the ~30 dB loss that would otherwise occur at the air-fluid interface.

Question 5

Cholesteatoma most commonly damages transmission by eroding which ossicle?

Accepted Answer

Long process of the incus

Answer

The long process of the incus is the most common site of erosion by cholesteatoma due to its relatively poor blood supply, causing ossicular discontinuity.

(ABA) American Board of Audiology Practice Test

(ABA) American Board of Audiology Practice Test

ABA Transmission & Drivetrain Systems 3