Question

1. How are sound waves transmitted through the outer, middle, and inner ears?

2. Distinguish between the osseous and membranous labyrinths.

3. Describe the spiral organ.

Answer 1

The process of hearing.

The hearing is a critical function which we rely on the most. Hearing occurs though out ears. Sound is a wave which is initiated by a movement outside the body like vibration of motion. The sound is transmitted through the ear via three distinct parts. The outer ear sense the air, the middle ear senses the mechanical and the inner ear senses the neural signalling. The air is transmitted via outer ear by pinna and then by ear canal. The movement of air inside the ear to the middle ear touches the tympanic membranes or ear drums. Here the sound from air is transferred to the vibrations on ear drum. The ossicular chain of ear drums are activated and the sound sets in the three bones of ossicular chain into action. From here, the sound vibrations are transferred to the liquid of the inner ear via the stapes. The motion in the cochlear fluid along with basils membrane creates a excitation frequency. This stimulates the series of nerve endings in the ear. Thus the sound wave is converted into nerve signal in the ear.

2- differences between the osseous and membranous labyrinths. The osseous is also called as bony labyrinth. It consists of bony cavities. It consists of cochlea, vestibules and three semi circular canals.it contains a fluid called perilymph.

The membrane labyrinth on the other hand, consists of cochlear duct, semi circular ducts, utricle and saccule.this is filled with fluid called endolymph.

3- the spiral organ is also known as organ of corti. It is located in the cochlea and is a receptor organ for hearing. It detects the fluid vibrations in the labyrinth and converts into nerve impulses. The movement of cochlear fluid and inner hair cells at the organ of corti produce the electrical signals. The organ os corti efficiently amplifies the sound by 22 times than it entered the ear.

The excessive sound levels lead to damage of corti organs leading to hearing loss.