Which sequence correctly describes the chain of events for transmitting sound energy from outside the body to neural signals?

Which sequence correctly describes the chain of events for transmitting sound energy from outside the body to neural signals?

• A. Air pressure causes tympanic membrane vibration; ossicles amplify; stapes transmits to cochlea; hair cells transduce; neurotransmitter release; auditory nerve fires.
• B. The auditory nerve fires prior to any mechanical event.
• C. Hair cells transduce before tympanic membrane vibrates.
• D. The cochlea activates the tympanic membrane directly.

Answer: (A)

Sound energy becomes neural signals through a precise mechanical-to-electrical chain: air pressure from a sound wave causes the tympanic membrane to vibrate, and those vibrations move the ossicular chain (the malleus, incus, and stapes) to amplify and transmit the motion to the cochlea at the oval window. This motion sets the cochlear fluids into waves, moving the basilar membrane and bending the hair cell stereocilia of the organ of Corti. That mechanical deflection opens ion channels in the hair cells, producing receptor potentials and triggering neurotransmitter release at the base of inner hair cells onto the afferent fibers of the auditory nerve. The auditory nerve then fires action potentials that carry the signal toward the brain. The other ideas conflict with the physical sequence: neural firing cannot precede mechanical events; hair cells cannot transduce before tympanic membrane vibration; and the cochlea does not activate the tympanic membrane directly.

Sound energy becomes neural signals through a precise mechanical-to-electrical chain: air pressure from a sound wave causes the tympanic membrane to vibrate, and those vibrations move the ossicular chain (the malleus, incus, and stapes) to amplify and transmit the motion to the cochlea at the oval window. This motion sets the cochlear fluids into waves, moving the basilar membrane and bending the hair cell stereocilia of the organ of Corti. That mechanical deflection opens ion channels in the hair cells, producing receptor potentials and triggering neurotransmitter release at the base of inner hair cells onto the afferent fibers of the auditory nerve. The auditory nerve then fires action potentials that carry the signal toward the brain. The other ideas conflict with the physical sequence: neural firing cannot precede mechanical events; hair cells cannot transduce before tympanic membrane vibration; and the cochlea does not activate the tympanic membrane directly.