NBC-HIS National Board for Certification in Hearing
Instrument Sciences Comprehensive Practice Exam
with 250 Questions and Detailed Rationales||
Complete Real Exam Questions And Correct Verified
Answers/ Graded A+|
This exam is based on the NBC-HIS content outline and covers all major
domains including anatomy, audiometric testing, tympanometry, earmold
selection, hearing instrument technology, troubleshooting, real ear
measurements, fitting, counseling, and professional practice. All questions are
original and designed to help you prepare for the actual board exam.
Section 1: Anatomy and Physiology of the Ear (Questions 1-15)
1. Which structure connects the scala tympani and the scala vestibuli?
A. Helicotrema
B. Organ of Corti
C. Basilar membrane
D. Tectorial membrane
Correct Answer: A
Rationale: The helicotrema is the opening at the apex of the cochlea that
connects the scala tympani and the scala vestibuli. This allows fluid movement
between the two chambers. The Organ of Corti is the sensory organ of
hearing. The basilar membrane supports the Organ of Corti. The tectorial
membrane overlies the hair cells.
,2. The primary function of the tympanic membrane is to:
A. Amplify sound by 20 dB
B. Transduce sound into electrical signals
C. Convert acoustic energy into mechanical vibrations
D. Equalize pressure in the middle ear
Correct Answer: C
Rationale: The tympanic membrane converts acoustic energy into mechanical
vibrations, which are then transmitted through the ossicles. Amplification
occurs through the ossicular chain and the area ratio of the tympanic
membrane to the stapes footplate. Transduction occurs in the cochlea.
Pressure equalization is the function of the Eustachian tube.
3. Which ossicle is attached to the tympanic membrane?
A. Stapes
B. Incus
C. Malleus
D. Lenticular process
Correct Answer: C
Rationale: The malleus is attached to the tympanic membrane. The incus
connects the malleus to the stapes. The stapes connects to the oval window.
The lenticular process is part of the incus.
,4. The Eustachian tube connects the middle ear to the:
A. Inner ear
B. Nasopharynx
C. External auditory canal
D. Mastoid air cells
Correct Answer: B
Rationale: The Eustachian tube connects the middle ear cavity to the
nasopharynx. It equalizes pressure between the middle ear and the
environment. The inner ear is connected via the oval and round windows. The
external auditory canal is separated by the tympanic membrane. The mastoid
air cells are connected to the middle ear but not the nasopharynx.
5. Which part of the cochlea is responsible for high-frequency sound
processing?
A. Apex
B. Middle turn
C. Base
D. Helicotrema
Correct Answer: C
Rationale: The base of the cochlea is responsible for high-frequency sound
processing. The apex is responsible for low frequencies. This is known as
tonotopic organization. The middle turn processes mid-frequencies. The
helicotrema is the opening at the apex.
, 6. The stapedius muscle contracts in response to:
A. Loud low-frequency sounds
B. Loud high-frequency sounds
C. Quiet sounds
D. Middle ear pressure changes
Correct Answer: A
Rationale: The stapedius muscle contracts in response to loud low-frequency
sounds as part of the acoustic reflex. The tensor tympani muscle also
contracts in response to loud sounds but is less sensitive. The stapedius
muscle is innervated by the facial nerve (CN VII).
7. Which cranial nerve innervates the stapedius muscle?
A. Trigeminal (CN V)
B. Facial (CN VII)
C. Glossopharyngeal (CN IX)
D. Vagus (CN X)
Correct Answer: B
Rationale: The stapedius muscle is innervated by the facial nerve (CN VII). The
tensor tympani muscle is innervated by the trigeminal nerve (CN V). The other
cranial nerves are not involved in the acoustic reflex.
Instrument Sciences Comprehensive Practice Exam
with 250 Questions and Detailed Rationales||
Complete Real Exam Questions And Correct Verified
Answers/ Graded A+|
This exam is based on the NBC-HIS content outline and covers all major
domains including anatomy, audiometric testing, tympanometry, earmold
selection, hearing instrument technology, troubleshooting, real ear
measurements, fitting, counseling, and professional practice. All questions are
original and designed to help you prepare for the actual board exam.
Section 1: Anatomy and Physiology of the Ear (Questions 1-15)
1. Which structure connects the scala tympani and the scala vestibuli?
A. Helicotrema
B. Organ of Corti
C. Basilar membrane
D. Tectorial membrane
Correct Answer: A
Rationale: The helicotrema is the opening at the apex of the cochlea that
connects the scala tympani and the scala vestibuli. This allows fluid movement
between the two chambers. The Organ of Corti is the sensory organ of
hearing. The basilar membrane supports the Organ of Corti. The tectorial
membrane overlies the hair cells.
,2. The primary function of the tympanic membrane is to:
A. Amplify sound by 20 dB
B. Transduce sound into electrical signals
C. Convert acoustic energy into mechanical vibrations
D. Equalize pressure in the middle ear
Correct Answer: C
Rationale: The tympanic membrane converts acoustic energy into mechanical
vibrations, which are then transmitted through the ossicles. Amplification
occurs through the ossicular chain and the area ratio of the tympanic
membrane to the stapes footplate. Transduction occurs in the cochlea.
Pressure equalization is the function of the Eustachian tube.
3. Which ossicle is attached to the tympanic membrane?
A. Stapes
B. Incus
C. Malleus
D. Lenticular process
Correct Answer: C
Rationale: The malleus is attached to the tympanic membrane. The incus
connects the malleus to the stapes. The stapes connects to the oval window.
The lenticular process is part of the incus.
,4. The Eustachian tube connects the middle ear to the:
A. Inner ear
B. Nasopharynx
C. External auditory canal
D. Mastoid air cells
Correct Answer: B
Rationale: The Eustachian tube connects the middle ear cavity to the
nasopharynx. It equalizes pressure between the middle ear and the
environment. The inner ear is connected via the oval and round windows. The
external auditory canal is separated by the tympanic membrane. The mastoid
air cells are connected to the middle ear but not the nasopharynx.
5. Which part of the cochlea is responsible for high-frequency sound
processing?
A. Apex
B. Middle turn
C. Base
D. Helicotrema
Correct Answer: C
Rationale: The base of the cochlea is responsible for high-frequency sound
processing. The apex is responsible for low frequencies. This is known as
tonotopic organization. The middle turn processes mid-frequencies. The
helicotrema is the opening at the apex.
, 6. The stapedius muscle contracts in response to:
A. Loud low-frequency sounds
B. Loud high-frequency sounds
C. Quiet sounds
D. Middle ear pressure changes
Correct Answer: A
Rationale: The stapedius muscle contracts in response to loud low-frequency
sounds as part of the acoustic reflex. The tensor tympani muscle also
contracts in response to loud sounds but is less sensitive. The stapedius
muscle is innervated by the facial nerve (CN VII).
7. Which cranial nerve innervates the stapedius muscle?
A. Trigeminal (CN V)
B. Facial (CN VII)
C. Glossopharyngeal (CN IX)
D. Vagus (CN X)
Correct Answer: B
Rationale: The stapedius muscle is innervated by the facial nerve (CN VII). The
tensor tympani muscle is innervated by the trigeminal nerve (CN V). The other
cranial nerves are not involved in the acoustic reflex.
