How human ear works?

The human ear is the organ that is specifically designed to perceive sound from the environment.

By "sound", we mean the sound waves that lie within the audible frequency range of 20 Hz to 20 kHz (or 20,000 Hz).

Other sound frequencies exist either below 20Hz (infrasonic) or above 20 kHz (ultrasonic), which the human ear fails to grasp.

However, do you know that this ear also serves an essential function for the body?

Yes, it does. A portion of the ear is responsible for maintaining the complete balance of the body.

Let’s delve deeper to explore the “hidden riches” of the simple human ear that we easily overlook.

The structure of the human ear

The outer top portion of the ear is called the "Helix", and its external lower elongation is the "Lobule".

The “ear canal” is the pathway that connects the outer ear with the inner ear.

Sound reaches the inner ear through the ear canal and ends when it hits the "eardrum".  

The hammer or malleus helps in the transmission of the sound vibrations.

The sounds travel from the eardrum into the incus and reach the stapes that remain attached to the surface of the oval window.

The direct contact of the malleus or hammer with the eardrum can prevent the eardrum from damage.

Thus, the malleus is not responsible for hearing impairment among individuals.

Auditory ossicles consist of the malleus, incus, and stapes. 

The various parts of the human ear and their individual functions

The human ear is divided into three primary portions – the Outer Ear, the Middle Ear, and the Inner Ear.

Let us examine each of the divisions in further detail.

1. The Outer Ear

The visible portion as seen on the outer ear – the auricle or pinna, gathers sound waves and transmits them inside the ear canal or the external auditory meatus for sound amplification.

After leaving the external auditory meatus or ear canal, the sound reaches an oval-shaped flexible membrane located toward the end of the ear canal, known as the tympanic membrane or the eardrum.

The eardrum begins to vibrate when the sound waves reach them.

The ear canal connects the outer ear with the eardrum (tympanic membrane).

Measuring around an inch by length, the skin in this ear canal possesses a high sensitivity to pressure and pain.

The eardrum appears as a size of a dime and remains the same size throughout the lifetime of an individual.

The covering hides two-thirds of bone and one-third of cartilage beneath the skin.

The eardrum appears transparent, like a clear plastic that is stretched out.

2. The Middle Ear 

The space available within the eardrum is called the middle ear. It consists of the three tiniest bones in the human body, known as “ossicles”.

The vibrations from the outer ear activate these ossicles when they hit the eardrum, which amplifies the sound further.

These three “tiny bones” or ossicles have their names according to their shapes – stapes (or stirrup), the malleus (hammer), and the incus (anvil).

The connection of the middle ear with the inner ear is made by this tiny stapes bone, also known as the malleus, which remains attached to the oval window in-between.

The malleus is visible through the semi-transparent layer of the eardrum.

The middle ear opening, also known as the Eustachian Tube, helps balance the pressure difference between the air on the outside of the ear and the air inside the middle ear.

3. The Inner Ear

The inner ear comprises two central portions – the cochlea, that aids in hearing, and the semi-circular canals that help maintain body balance.

These labyrinthine or semi-circular canals are arranged at right angles (or 90 degrees) with one another.

Such an arrangement enables the brain to identify the movement direction of the head. 

When the head begins to move, the fluids present in the semi-circular canals start to shift from their place.

Such a change affects the electrical impulses being sent into the brain, which then takes the necessary steps to bring the body back into balance.

The semi-circular canals carry fluids stored in them with embedded calcium crystal linings.

The sound waves travel from the outside through the outer and middle ear portions and enter the inner ear.

These waves reach the snail-shaped organ, known as the cochlea, full of "fluids"; that move when vibrations hit the oval window from the outside.

Hair cells respond to the vibrations in the sound.

When the ossicles act like a piston, they form a wave in the fluid present in the inner ear.

The fluid motion activates about 25,000 nerve endings that help to convert these vibrations into neuro-electric impulses.

These developed impulses reach the brain through the auditory nerve (or eighth cranial nerve).

The fibers in the auditory nerves transfer the "sound information" sends them into the brain. 

The eighth cranial nerve comes in through the inner ear and runs straight inside the brain.

The seventh cranial nerve (or the facial nerve) also runs along the eighth cranial nerve.

This nerve helps to supply neural impulses into the face muscles.   

When these impulses reach the brain, it perceives the “received impulse” into “valuable information”.

In this way, people can achieve "hearing" and listen to the conversation of one another.

The vestibular organ situated in the inner ear helps the body to stay in balance.

Keep your ear clean

We have seen from the above information that the human ear possesses more than what meets the eye.

Yes, the ear serves a vital function to gather sound waves and converts them into meaningful information.

But the ear also helps the body to maintain its balance.

It is advisable to clean your ear occasionally. 

Dust particles keep accumulating in the ear canal and block the passage for sound to reach the eardrum.

Clean the ear canal with a soft cotton bud by applying slight pressure.

Increasing the pressure can push the particles further inside and might damage the eardrum.