Question

Draw a labelled diagram of human ear, explaining how the energy of the sound wave is transmitted to nerves in the Cochlea​

Answer 1

Draw a labelled diagram of the ear. Write a note on the mechanism of hearing.

The external ear receives and collects the sound waves and then directs them to the eardrum. The sound waves travel through the external auditory canal. The eardrum vibrates and these vibrations are passed to the three ear ossicles (malleus, incus and stapes) in the middle ear.

The ear ossicles increase the intensity of the sound vibrations and transmit them to the oval window. The vibrations pass through the oval window till the cochlea where they generate the waves in the lymph present in the cochlea.

Firstly the waves are generated in the perilymph present in the scala vestibuli and then in the endolymph present in the scala media. The waves in the endolymph induce a ripple in the basilar membrane. The basilar movements bend the hair cells present in the organ of Corti pressing them against the tectorial membrane. This generates the nerve impulse in the associated afferent neurons. The impulse gets transmitted to the auditory region of the brain via the auditory nerve. The impulse gets analysed and thus the sound is recognised.

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Answer 2

Explanation

HUMAN EAR -

• Human ears are the openings to receive sound waves and transmit the signals to the brain.
• The ear has three portions: Outer, middle, and inner ear.

Mechanism -

• The outer ear consists of the pinna and collects the signals and transmits them to the external auditory canal.
• The canal is a long tube extending to the tympanic membrane, the middle ear.
• Tiny bones(malleus, incus, stapes) are attached to the eardrum that further amplifying the sound signals before sending them to the inner ear.
• The vibrations are then transferred to the inner ear, the spiral-shaped cochlea.
• The fluid in the cochlea vibrates and causes rippling of the basilar membrane.
• The hair cells on the basilar membrane detect the waves based on the pitch of the sound causing the bending of stereocilia, the microscopic hair cell projections.
• The pore-like channels open and the rushing of chemicals produces electrical signals from the sound waves.
• The electrical signals are then transmitted by the auditory nerve to the brain.