HIS Ear Anatomy & Physiology 4

Question 1

Damage to outer hair cells most commonly results in which type of hearing loss pattern on an audiogram?

Accepted Answer

Sensorineural hearing loss, typically worse at high frequencies

Answer

OHCs at the basal (high-frequency) end of the cochlea are most vulnerable to noise and ototoxins, producing the classic high-frequency sloping sensorineural loss.

Question 2

The helicotrema is located at which end of the cochlea and serves what function?

Accepted Answer

Apex; connects scala vestibuli and scala tympani so fluid can flow between them

Answer

The helicotrema is a small opening at the cochlear apex where the scala vestibuli and scala tympani communicate, allowing very-low-frequency fluid pressure to equalize.

Question 3

Which of the three ossicles is directly attached to the tympanic membrane?

Accepted Answer

Malleus

Answer

The handle (manubrium) of the malleus is embedded in the fibrous layer of the tympanic membrane, making it the first ossicle to receive vibrations from the eardrum.

Question 4

The impedance mismatch between air and cochlear fluid is overcome by the middle ear transformer. What is the primary mechanism?

Accepted Answer

Hydraulic lever effect from the large tympanic membrane area relative to the small oval window area

Answer

The tympanic membrane's area (~55 mm²) is about 17–20 times larger than the oval window (~3.2 mm²), concentrating force and providing most of the ~25–30 dB pressure gain needed to overcome the air-to-fluid impedance barrier.

Question 5

Otoacoustic emissions (OAEs) are generated by which cochlear structure?

Accepted Answer

Outer hair cells

Answer

OAEs are sounds produced by the active electromotility of outer hair cells; they travel backward through the middle ear and can be recorded in the ear canal with a sensitive microphone.

(HIS) Hearing Instrument Specialist Certification Practice Test

(HIS) Hearing Instrument Specialist Certification Practice Test

HIS Ear Anatomy & Physiology 4