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Physio: 8# Hearing
Q1. A sound wave with higher pitch but same loudness compared to another sound differs mainly in which physical property?
Amplitude
Frequency
Velocity in air
Wavelength only
Explanation:
Pitch depends on frequency, whereas loudness depends on amplitude.
Q2. Which statement about sound transmission is CORRECT?
Sound travels fastest in gases
Sound cannot travel through solids
Sound needs a vacuum to propagate
Sound cannot be transmitted in vacuum
Explanation:
Sound requires a medium and cannot propagate in vacuum.
Q3. The major factor responsible for the 22-fold amplification of sound in the middle ear is:
Lever action of ossicles alone
Curvature of tympanic membrane
Area difference between tympanic membrane and oval window
Resonance of middle ear cavity
Explanation:
Area ratio (~17×) combined with lever action (~1.3×) gives ~22× amplification.
Q4. Paralysis of the stapedius muscle would most likely result in:
Hyperacusis
Conductive deafness
Loss of pitch discrimination
Vertigo
Explanation:
Stapedius dampens loud sounds; paralysis causes increased sound perception (hyperacusis).
Q5. The attenuation reflex is LEAST effective in preventing cochlear damage because:
It reduces high-frequency transmission only
It has a latent period of about 100 ms
It fatigues rapidly
It acts only during speech
Explanation:
Sudden loud sounds cause damage before the reflex becomes active.
Q6. Which cochlear compartment contains endolymph?
Scala vestibuli
Scala tympani
Round window
Scala media
Explanation:
Scala media contains potassium-rich endolymph.
Q7. The positive electrical potential of endolymph (+80 mV) is essential for:
Driving K⁺ influx into hair cells during stimulation
Generation of action potentials in the cochlea
Calcium channel activation
Sodium influx into hair cells
Explanation:
Large electrochemical gradient drives potassium influx → depolarization.
Q8. Opening of which ion channel directly depolarizes cochlear hair cells?
Sodium
Calcium
Potassium
Chloride
Explanation:
Deflection of stereocilia opens mechanically gated K⁺ channels.
Q9. Damage to inner hair cells results in:
Complete hearing loss
Mild high-frequency loss
Loss of sound localization only
Tinnitus without hearing loss
Explanation:
Inner hair cells provide 90–95% of afferent input.
Q10. The primary function of outer hair cells is to:
Transmit sound impulses to cortex
Modulate sensitivity of inner hair cells
Generate endolymph
Protect cochlea mechanically
Explanation:
Outer hair cells amplify and fine-tune cochlear responses.
Q11. High-frequency sounds maximally vibrate which part of basilar membrane?
Apex
Distal end
Flexible segment
Basal end
Explanation:
Basal end is narrow and stiff → high-frequency tuning.
Q12. Presbyacusis primarily affects hearing of:
High frequencies
Low frequencies
Speech sounds only
All frequencies equally
Explanation:
Age-related loss begins at cochlear base (high-frequency region).
Q13. Localization of low-frequency sounds depends mainly on:
Intensity difference between ears
Time difference of sound arrival
Pinna reflection
Basilar membrane stiffness
Explanation:
Interaural time differences localize low-frequency sounds.
Q14. The structure where timing and intensity differences from both ears are first compared is:
Inferior colliculus
Medial geniculate body
Superior olivary nucleus
Auditory cortex
Explanation:
Superior olivary nucleus is essential for sound localization.
Q15. Lesion of the primary auditory cortex on one side causes:
Complete deafness
Ipsilateral deafness
Bilateral hearing loss
Difficulty localizing sound
Explanation:
Bilateral auditory input prevents complete deafness.
Q16. Brodmann areas 41 and 42 correspond to:
Visual cortex
Primary auditory cortex
Secondary auditory cortex
Wernicke’s area
Explanation:
Areas 41 & 42 receive auditory input from MGB.
Q17. Wernicke’s area damage leads to:
Impaired interpretation of sounds
Motor aphasia
Complete deafness
Loss of sound localization
Explanation:
Wernicke’s area is involved in auditory interpretation.
Q18. The round window primarily functions to:
Transmit sound waves
Amplify vibrations
Release pressure waves
Generate perilymph
Explanation:
Acts as a pressure release valve.
Q19. Outer hair cells receive predominantly:
Afferent fibers
Autonomic fibers
Sensory fibers only
Efferent fibers
Explanation:
95% of outer hair cells are innervated by efferent fibers.
Q20. Hearing sensitivity is greatest for frequencies between:
20–200 Hz
1000–4000 Hz
8000–12000 Hz
15,000–20,000 Hz
Explanation:
Human speech frequencies fall in this range.