ear functioning

Question 1

Stage 1 of hearing

Answer 1

1. Pathway of sound waves

The pinna directs sound waves into the external auditory canal.
⏬️
The eardrum vibrates when struck by these sound waves
⏬️
The tympanic membrane ossciles conduct these vibrations across the middle ear to the oval window membrane.
⏬️
This membrane vibrates and causes waves in the perilymph of the vestibule.
⏬️
These waves move along the scala vestibule of the cochlea and cause the vestibular membrane to vibrate.
⏬️
This results in waves in the endolymph in the cochlear duct which in turn causes the basilar membrane to vibrate.
⏬️
These vibrations stimulate the receptor hair cells of the organ of Corti.

Question 2

Sage 2 of hearing

Answer 2

2. Generation of impulses

The hairs of the receptor cells are embedded in the jelly-like tectorial membrane.
🡻
As the organ of Corti moves up and down on the vibrating basilar membrane, the hairs are bent and stretched.
🡻
This shearing action converts this mechanical stimulus into an impulse.
🡻
The hair cells in different parts of the cochlear respond to different frequencies of vibration.

Question 3

Stage 3 of hearing

Answer 3

C. Pathway of impulses

The impulses are conducted via the cochlear nerve and then the auditory nerve to the temporal lobe of the cerebral cortex where the sensation of sound is interpreted.