Answer: From the question,the correct order of how hearing works is listed below:
--> sound wave is generated from hitting a key on a piano,
--> Incus moves,
--> Stapes moves,
--> Sound wave enters inner ear,
--> Fluid in the cochlea moves,
--> Fluid wave moves across Organ of corti based on frequency,
--> Ions enter hair cells,
--> hair cells bend,
--> auditory nerve transmits the signal to the auditory cortex,
--> auditory cortex recognizes the sounds.
Explanation:
In mammal, two ears are present on each side of the head. It is know as the organ for hearing and balance. The ear is divided into three regions:
--> OUTER EAR: This consists of pinna, ear canal, and eardrum( tympanic membrane)
--> MIDDLE EAR: This consists of the ear ossicles ( malleus, incus and stapes).
--> INNER EAR: This consists of Cochlea (organ of hearing) and semicircular canals (for balance).
To explain further on how we hear sounds, the vibrations of sounds produced from an external source move from the outer ear to the middle and then to the inner ear where the cochlea, the organ for hearing is located.
As sound wave is generated from hitting a key on a piano, the pinna collects the sound waves and directs them into the ear canal. Sound waves impinge on the tympanic membrane and makes it vibrate. This causes the malleus, incus and stapes (in this order) to move to-and -fro at the middle ear region.
In the inner ear region, sound wave enters inner ear as stapes pushes the oval window in-and-out. The vibrating oval window causes the fluid in the cochlea( perilymph) to move to-and -fro. Fluid wave moves across Organ of corti based on frequency. The pressure waves in the perilymph push the membrane separating the upper canal and the cochlear duct to-and-fro allowing ions to enter the hair cells. As a result, the hairs of the sensory cells between these two membranes bend causing nerve impulses to be sent to the brain through the cochlear part of the auditory nerve. Auditory nerve transmits the signal to the auditory cortex which recognizes the sounds.
