MCQs: Physiology of Hearing – For NEET PG & University Exams

MCQs: Physiology of Hearing – For NEET PG & University Exams

What is the primary function of the external auditory meatus in hearing?
A. Amplify sound intensity
B. Conduct sound waves to the tympanic membrane
C. Localize sound source
D. Protect the inner ear
What is the speed of sound in air at 20°C and sea level?
A. 300 m/s
B. 344 m/s
C. 400 m/s
D. 500 m/s
Which mechanism primarily addresses the 99.9% sound energy reflection at the air-liquid interface?
A. Attenuation reflex
B. Impedance matching
C. Phase differential
D. Natural resonance
What is the total amplification factor of the middle ear due to lever and hydraulic actions, as per the primary text?
A. 14:1
B. 17:1
C. 18:1
D. 22.1:1
Which muscle contracts during the attenuation reflex to restrict ossicular movement?
A. Tensor veli palatini
B. Stapedius
C. Levator tympani
D. Mylohyoid
What is the human auditory system’s frequency detection range?
A. 10–10,000 Hz
B. 20–20,000 Hz
C. 50–50,000 Hz
D. 100–100,000 Hz
In auditory transduction, what causes depolarization of hair cells?
A. Oval window vibration
B. Stereocilia bending
C. Round window movement
D. Perilymph flow
Which potential is used diagnostically for Meniere’s disease?
A. Endo-cochlear potential
B. Cochlear microphonic
C. Summating potential
D. Compound action potential
According to the E COLI-MM mnemonic, which structure follows the cochlear nucleus in the auditory pathway?
A. Eighth nerve
B. Olivary complex
C. Inferior colliculus
D. Medial geniculate body
What is the natural resonance frequency of the ossicular chain?
A. 800 Hz
B. 1600 Hz
C. 3000 Hz
D. 500–2000 Hz
Clinical Scenario: A 28-year-old male presents with sudden sensorineural hearing loss after exposure to a loud explosion at a construction site. Which mechanism’s failure likely contributed to his cochlear damage?
A. Impedance matching
B. Attenuation reflex
C. Phase differential
D. Auditory transduction
Clinical Scenario: A 45-year-old female reports episodic vertigo, tinnitus, and hearing loss. Electrocochleography reveals an elevated summating potential. What is the most likely diagnosis?
A. Otosclerosis
B. Meniere’s disease
C. Acoustic neuroma
D. Presbycusis
Clinical Scenario: A 35-year-old male with chronic otitis media presents with conductive hearing loss. Which middle ear component is most likely affected, disrupting sound conduction?
A. Pinna
B. Ossicular chain
C. Cochlea
D. Semicircular canals
Clinical Scenario: A patient’s otoscopy shows a non-vibrating tympanic membrane during loud sound exposure, suggesting attenuation reflex dysfunction. Which muscle is primarily implicated?
A. Tensor tympani
B. Sternocleidomastoid
C. Masseter
D. Buccinator
Clinical Scenario: A 30-year-old female reports difficulty localizing sounds in crowded places. An MRI reveals a temporal lobe lesion. Which cortical area is most likely affected?
A. Brodmann’s area 41
B. Brodmann’s area 17
C. Brodmann’s area 4
D. Brodmann’s area 8
Clinical Scenario: A 40-year-old male undergoes pure tone audiometry, revealing a hearing threshold elevation at 4000 Hz. What is the most likely underlying cause?
A. External auditory canal obstruction
B. Ossicular chain fixation
C. Cochlear hair cell damage
D. Auditory cortex lesion
Clinical Scenario: A 55-year-old factory worker presents with difficulty understanding speech in noisy environments. Which frequency range, critical for conversation, is most likely affected?
A. 100–500 Hz
B. 1000–3000 Hz
C. 5000–8000 Hz
D. 10,000–15,000 Hz
Clinical Scenario: A patient with suspected ossicular discontinuity is evaluated. What is the expected effect on sound transmission to the cochlea?
A. Increased sound pressure
B. Reduced oval window pressure
C. Enhanced phase differential
D. Unaltered transduction
Clinical Scenario: A 32-year-old female with tinnitus and unilateral hearing loss shows an abnormal compound action potential on testing. Which structure is most likely affected?
A. Tympanic membrane
B. Auditory nerve
C. External auditory meatus
D. Tectorial membrane
Clinical Scenario: During stapedectomy, an ENT surgeon notes a fixed stapes footplate. Which hearing mechanism is primarily disrupted?
A. Attenuation reflex
B. Impedance matching
C. Neural conduction
D. Natural resonance

Which of the following contributes to the phase differential between the oval and round windows?
Tensor tympani contraction
B. Ossicular coupling
C. Cochlear microphonic potential
D. Endo-cochlear potential
A patient with noise-induced hearing loss shows a dip at 4000 Hz on audiometry. Which structure is primarily damaged?
Tympanic membrane
B. Ossicular chain
C. Organ of Corti
D. Auditory cortex
The auditory cortex is located in which Brodmann’s area?
Area 17
B. Area 41
C. Area 4
D. Area 8
Which of the following potentials is a graded, non-propagated response used in diagnosing Meniere’s disease?
Compound action potential
B. Endo-cochlear potential
C. Summating potential
D. Action potential
A patient with conductive hearing loss has a disrupted ossicular chain. What is the primary mechanism affected?
Auditory transduction
B. Impedance matching
C. Neural conduction
D. Sound localization

Answers with Detailed Explanations

B. Conduct sound waves to the tympanic membrane: The external auditory meatus channels sound waves to the tympanic membrane, causing it to vibrate. Amplification (A) occurs in the middle ear, localization (C) is primarily the pinna’s role, and protection (D) is secondary.
B. 344 m/s: The text specifies sound travels at 344 m/s in air at 20°C and sea level. Options A, C, and D are incorrect as they deviate from this value.
B. Impedance matching: Impedance matching overcomes the 99.9% sound energy reflection at the air-liquid interface using ossicular lever action (1.3x), hydraulic action (14:1), and curved tympanic membrane effect. Attenuation reflex (A) protects against loud sounds, phase differential (C) aids fluid movement, and natural resonance (D) enhances frequencies, but none address reflection.
C. 18:1: The text states the product of the areal ratio (14:1) and lever action (1.3x) yields 18:1 amplification. Option D (22.1:1) is from Wever and Lawrence’s study, not the primary text. Options A and B are incorrect ratios.
B. Stapedius: The stapedius muscle, along with tensor tympani, contracts during the attenuation reflex to restrict ossicular movement for loud sounds (>70 dB). Other options (A, C, D) are unrelated to the middle ear.
B. 20–20,000 Hz: The text confirms the human auditory range is 20–20,000 Hz. Other options are either too narrow or too broad.
B. Stereocilia bending: Stereocilia bending in the organ of Corti opens cation channels, causing depolarization during auditory transduction. Oval window (A) initiates perilymph movement, round window (C) facilitates fluid dynamics, and perilymph flow (D) is indirect.
C. Summating potential: The summating potential, a DC receptor potential, is used to diagnose Meniere’s disease. Endo-cochlear potential (A) is resting, cochlear microphonic (B) is AC, and compound action potential (D) is neural.
B. Olivary complex: The mnemonic E COLI-MM (Eighth nerve, Cochlear nucleus, Olivary complex, Lateral lemniscus, Inferior colliculus, Medial geniculate body, Auditory cortex) indicates the olivary complex follows the cochlear nucleus. Other options are incorrect in sequence.
D. 500–2000 Hz: The ossicular chain’s natural resonance is 500–2000 Hz, contributing to conversational frequency amplification. Other options refer to different structures or are incorrect.
B. Attenuation reflex: The attenuation reflex (stapedius, tensor tympani) protects against loud sounds (>70 dB) but has a 40 ms latency, failing to shield the cochlea from sudden noises like explosions, causing sensorineural hearing loss. Impedance matching (A) amplifies sound, phase differential (C) aids fluid movement, and transduction (D) is a cochlear process, none protective.
B. Meniere’s disease: Elevated summating potential on electrocochleography, with vertigo, tinnitus, and hearing loss, indicates Meniere’s disease due to endolymphatic hydrops. Otosclerosis (A) causes conductive loss, acoustic neuroma (C) affects the auditory nerve, and presbycusis (D) is age-related, none linked to summating potential.
B. Ossicular chain: Chronic otitis media can erode the ossicular chain, disrupting impedance matching and causing conductive hearing loss. Pinna (A) and meatus (C) are external, cochlea (C) causes sensorineural loss, and semicircular canals (D) affect balance.
A. Tensor tympani: A non-vibrating tympanic membrane during loud sounds suggests attenuation reflex dysfunction, primarily involving the tensor tympani, which pulls the malleus inward. Stapedius (not an option) also contributes, but other muscles (B, C, D) are irrelevant.
A. Brodmann’s area 41: The auditory cortex (Brodmann’s area 41) processes sound localization; lesions impair this ability. Area 17 (B) is visual, area 4 (C) is motor, and area 8 (D) controls eye movement.
C. Cochlear hair cell damage: A 4000 Hz dip on audiometry indicates sensorineural hearing loss from cochlear hair cell damage, common in noise exposure. External canal obstruction (A) or ossicular fixation (B) cause conductive loss, and cortical lesions (D) affect localization.
B. 1000–3000 Hz: The minimum audibility curve shows peak sensitivity at 1000–3000 Hz, critical for conversational speech. Noise exposure likely damages this range. Other ranges (A, C, D) are less relevant for speech.
B. Reduced oval window pressure: Ossicular discontinuity disrupts impedance matching, reducing pressure transmission to the oval window, causing conductive hearing loss. It doesn’t increase pressure (A), enhance phase differential (C), or affect transduction (D).
B. Auditory nerve: An abnormal compound action potential indicates auditory nerve dysfunction, common in tinnitus and hearing loss (e.g., acoustic neuroma). Other structures (A, C, D) affect earlier stages.
B. Impedance matching: A fixed stapes (e.g., otosclerosis) disrupts impedance matching, reducing pressure transfer to the oval window. Attenuation reflex (A), neural conduction (C), and resonance (D) are unaffected.

Ossicular coupling: Ossicular coupling, part of the intact tympano-ossicular system, ensures the oval window vibrates preferentially, creating a phase differential with the round window (+4 dB gain). Tensor tympani (A) is for attenuation, cochlear microphonic (C) is a transduction potential, and endo-cochlear potential (D) powers transduction.
Organ of Corti: A 4000 Hz dip indicates noise-induced sensorineural hearing loss due to organ of Corti hair cell damage. Tympanic membrane (A) and ossicles (B) cause conductive loss, and auditory cortex (D) affects localization.
Area 41: The primary auditory cortex is Brodmann’s area 41, per the text. Area 17 (A) is visual, area 4 (C) is motor, and area 8 (D) controls eye movement.
Summating potential: Summating potential, a graded, non-propagated DC potential, is diagnostic for Meniere’s disease. Compound action potential (A) is neural, endo-cochlear (B) is resting, and action potential (D) is generic.
Impedance matching: Ossicular chain disruption impairs impedance matching, reducing sound transmission to the cochlea, causing conductive hearing loss. Transduction (A), neural conduction (C), and localization (D) are unaffected.

———— End of the chapter ————

Reference Textbooks.

Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
Glasscock-Shambaugh, Textbook of Surgery of the Ear.
P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
Hazarika P, Textbook of Ear Nose Throat And Head Neck Surgery Clinical Practical.
Mohan Bansal, Textbook of Diseases of Ear, Nose and Throat Head and Neck Surgery
Hans Behrbohm, Textbook of Ear, Nose, and Throat Diseases With Head and Neck Surgery.
Salah Mansour, Middle Ear Diseases – Advances in Diagnosis and Management.
Logan Turner, Textbook of Diseases of The Nose, Throat and Ear Head And Neck Surgery.
Rob and smith, Textbook of Operative surgery.
Anirban Biswas, Textbook of Clinical Audio-vestibulometry.
Arnold, U. Ganzer, Textbook of Otorhinolaryngology, Head and Neck Surgery.

Author:

Dr. Rahul Bagla MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi) Fellow Rhinoplasty & Facial Plastic Surgery. Renowned Teaching Faculty Mail: msrahulbagla@gmail.com India

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Please read. Anatomy of External Ear. https://www.entlecture.com/anatomy-of-ear/
Please read. Anatomy of Temporal Bone. https://www.entlecture.com/anatomy-of-temporal-bone/
Please read. Stenger’s, Chimani Moos, Teal test. https://www.entlecture.com/special-tuning-fork-tests/

Keywords: PPT Free Download, Mechanism, Flowchart, Diagram, Notes, Auditory physiology, Cochlear function, Basilar membrane movement, Sound transduction, Hair cell depolarization, Auditory neural pathway, Endolymphatic potential, Cochlear microphonics, Tonotopic organization, Middle ear amplification, Oval window vibration, Inner ear hair cells, Otolithic membrane, Stereocilia deflection, Auditory nerve action potential, Brainstem auditory processing, Temporal coding in hearing, Physiology of Hearing