Structure and Function of Human Ear

Definition

Sensation – Sensing the external or internal stimuli.

Sensory Process - The process of detection of external or internal stimuli through the activation of sense organs (Eyes, ear, nose, skin and tongue).

Sensory Process

          Human activities results from the orders of brain which gets inputs from the various sense organs. The sense organs are activated by stimuli from the internal or external environment. The collective efforts of sensory organs, neurons, tissues, muscles, bones, brain and mind helps in receiving, organizing and finally interpreting the stimuli. The sensory receptors  (Specialized cells) of sense organs transform external or internal physical stimuli into electro-chemical signals known as neural impulse that travels via various channels to specific brain centres for further processing. This whole process of converting stimuli into neural impulse is known as sensory process.

Structure of Human Ear

          For better understanding the human ear is divided into three following subdivisions: -

1.       Outer or External Ear – The components of outer ear are Pinna & auditory canal

2.     Middle Ear – It contains tympanum (ear drum), tympanic cavity, three ossicles i.e. malleus (hammer), incus (anvil), and stapes (stirrup).

3.       Inner Ear – It is encapsulated in bony shell called bony labyrinth. The bony labyrinth has three semi-circular canals at right angle to each other, a cavity (Vestibule) and a coiled structure (Cochlea).

Function of Each Part

1.       Outer or External Ear – Collects and carries sound waves to tympanum or ear drum.

2.       Middle Ear – Increases the intensity of sound vibrations about 10 times and send them to the inner ear.

3.       Inner Ear – Converts sound waves into neural impulse with the help of Organ of Corti (Main organ of hearing made up of fine hair cells).

Function of an Ear

          The sound waves are collected by pinna that moves through the auditory canal to vibrate tympanic membrane (Eardrum). The eardrum vibrates the hammer, anvil, and stirrup (three ossicles) which intensifies the sound waves and vibrate the oval window (Cochlea). The vibration of cochlea made to vibrate fluid inside it. The fluid vibrates the basilar membrane, which causes the organ of Corti to move up and bend its hair cell (Ciccarelli & Meyer, 2016). The bending of hair cell (More bending louder the sound) converts vibrations into neural impulse which are transported to brain centres via auditory nerve. 

Some Important Terms

1.       Hertz (Hz) (Unit of frequency) – Waves per second.

2.       Auditory Canal – A tube like structure that starts from pinna and reaches up

to eardrum.

3.       Tympanic membrane – Eardrum.

4.       Cochlea – The structure of inner ear that resembles snail shape.

5.       Organ of Corti – An organ consisting of hearing receptor cells (Hair cells).

6.     Auditory nerve – A bundle of axons of neurons that starts from organ of Corti and reaches to the brain.

Reference:

1.       NCERT, XI Psychology Text book.

2.       Ciccarelli, S. K. & Meyer, G. E. (2016). Psychology. Noida: Pearson India.

3.       Baron, R. (1993).  Psychology.

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