Question

High frequency sound waves vibrate basilar membrane
A. Near helicotrema
B. In middle of cochlea
C. From oval window to helicotrema
D. Near oval window

Answer 1

When sound waves from the ones surrounding enter the external ear, they are directed to eardrum also known as tympanic membrane. The eardrum vibrates on receiving the sound waves as well as the vibrations are further sent to oval window through ear ossicles
that are malleus, incus as well as stapes.

Complete answer:
Option A- The helicotrema is the part of the cochlear labyrinth where the scala tympani along with the Scala vestibuli meets. It is the key component of the cochlear apex. The hair cells near this area best detect low frequency sounds to flow.
Option B – The cochlea is a portion of the inner ear that looks like a snail shell. The cochlea receives sound in the form of vibrations, that cause the stereocilia to move. The stereocilia then transform into these vibrations then into nerve impulses that are taken up to the brain to be interpreted.
Option C - In reaction to acoustic stimulation of the ear, sound pressure is disseminated into scala vestibuli via the stapes at the oval window. Sound pressure travels superiorly to the apex of the cochlea where it upholds through the helicotrema into Scala tympani.
Option D – The oval window is a membrane covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles further into the inner ear. The oval window is the intersection of the middle ear with the inner ear as well as is directly contacted by the stapes; by the time vibrations arises the oval window, they have been already amplified over 10 times from what they were when they first contacted the tympanic membrane, a testament to the amplifying power is in the middle ear.

Hence, the correct answer is option (D).

Note: From the oval window, the vibrations further pass into a fluid of cochlea where waves are generated into lymph because of these vibrations. These waves produce vibrations in the basilar membrane that bend the hair cells as well as press them against the tectorial membrane.