Humans use their ears to hear. This ear is one of the five senses that helps in responding to verbal or non-verbal communication between any other person. If there is any problem in hearing, then it mostly affects speech and language. Hearing impairment is such a disability, due to which the affected person has to face difficulty in listening and understanding as compared to a normal person. But gradually scientific discoveries, artificial devices and technology are proving helpful in providing special education to children/persons suffering from hearing impairment like normal people. Still, it is important to find ways to avoid hearing impairment and for this it is necessary for all of us to know what can be the reasons for hearing impairment. This can help us in preventing hearing impairment. Just as a blind child is unable to see any object in the world, he can only imagine that object by touching it. In the same way, a hearing impaired child is separated from the world of sounds of the world. Voice is such a window of our speech through which a person communicates verbally with each other, that is, hearing disability has the greatest effect on our speech and language, due to which communication also becomes difficult.

Hearing impairment-
This can be of any kind and to any extent. When the extent of hearing impairment becomes more severe, the natural progress of language and speech is hindered. Along with this, verbal conversation is hindered. We call this hearing impairment or deafness.

(Definition of hearing disability Hearing impairment may include any type of defect or abnormality such as psychological, physical or physiological in structure or functions.)

According to Asha 1981- “Hearing impairment is a deviation or change in which the hearing function goes out of the normal range due to excessive disturbance.”

According to the World Health Organization- “A human being’s manner and various types of activities, whether it is damage or disability, can be determined on the basis of its various types of deficiencies.”

According to Rehabilitation Council of India- “Hearing disability means hearing impairment with deafness. Hearing impairment is more than 70 decibels in the better ear or complete hearing loss in both ears.

Structure of the Ear

• Our ears are the most responsible organ for listening to the communication we express. A detailed study of the structure of the ear is necessary to know how the process of hearing is completed and what is the role of which part of the ear. By studying this, we can get information not only about the hearing process but also about the obstructing problems in it. The ear is divided into three parts.
  

• Outer part
• Middle part
• Inner part
  

1. 1. External part- The external part of the ear is very important from its protective point of view. The organs attached to it help in the hearing process. External part The external part of the ear is very important from its protective point of view. The organs attached to it help in the hearing process. The ear can be depicted like this. It also has three main parts-

Main parts of the ear

Upper ear	Incus
Middle ear	Convulsive sensory nerve
Inner ear	Fascial nerve
Ear leaf	Coccytia
Eardrum	Hatix
Oval window	Conca
Vastibule	Tympanic cavity
Metipus	Internal auditory canal
Sempervirens/Tubule	Internal carotid artery
Vestibular nerve	Stacian tube
Pharyx	Tympanic tube
Curved window

(a) Pinna or Auricula

b) External auditory canal

c) Eardrum or Tympanic Membrane

(a) Pinna or Auricula- It is a flat, funnel-like part spread on the head like a fan. It is made up of light yellow coloured fibres. It has elastic fibro cartilage covered with hairy skin. It can be moved voluntarily by muscles.

(b) External Auditory Canal- ear canal is a small canal of about 24 mm., extending inwards from the base of the earlobe, the front part of which is 16 mm and the back and narrow part is 8 mm.

(c) Eardrum – This membrane like curtain whose diameter is 25 cm is connected to the external ear canal. It is light blue in colour.

 

2. 2. Middle part – The middle part of the ear is in the form of an asymmetrical cavity filled with air from the eardrum towards the inside. Which is called tympanic cavity. The membrane around it is covered with fine mucus. The middle ear has mainly four important parts, whose union together completes the structure of the middle ear. These important organs are as follows-

 

• • Bones

• • Muscles

• • Window

• • Eustachian tube

(1) Bones- There are three bones connected to each other by joints running behind each other inside the ear cavity. That is why we call them tiny bones (Tiny or Smallest Bone or Osscles). These three bones joined together look like a chain. There is no stability in them because they keep moving in their place. Being joined together, they are also called ascular chain. The description of these three bones is as follows-

A. Malleus- It is the largest bone among the three bones and its structure is like a hammer. One end of it is connected to the membrane and the other end is connected to the incus.

B. Incus- Incus is the bone connecting malleus and stapes which we also call anvil.

C. Stapes- It is the smallest bone of the body. Its shape is like a horse’s hoof or tuning fork, hence it is also called horse shoe shaped. The main part of the stapes bone is connected to the incus. Its foot plate opens above the oval window. This bone forms the connection between the middle ear and the inner ear and this connection is connected to the scalla vestibuli of the inner ear.

(2) Muscles- The main function of the muscles in the middle ear is to maintain mutual harmony, which protects the delicate organs necessary for hearing loud sounds coming from outside. It is of two types.

A. Tensor tympani- Its first end is attached to the malleus bone and the other end to the anterior wall. When sound enters the three bones through the eardrum, then there is movement in these bones. The tensor tympani muscle pulls the malleus bone inwards and motivates it to work as much as possible.

B. Stapedius– One end of this muscle is attached to the stapes bone while the other end is attached to the back wall. When these muscles contract, they pull the stapes bone out.

(3) Window- Two types of windows are found at the end of the middle ear and this end divides the middle ear and the inner ear. Both these windows are of the following types-

A. Oval Window- The oval window situated at the end of the middle ear marks the beginning of the inner ear. The stapes bone is inserted in this oval window. Here, the sound waves coming from the ear reach the inner ear through the oval window through this stapes bone.

B. Round Window- The round window is situated just below the oval window and there is a thin membrane layer on top of it.

(4) Eustachian Tube- This tube connects the middle ear to the nose. Its length is 30-40 mm. In children, this tube is small and wide and in adults, this tube is a little bigger and vertical. Normally, this tube remains closed but opens automatically while swallowing something, laughing loudly, sneezing or yawning. The function of this tube is to maintain the air pressure inside the middle ear in a normal state.

3 Inner ear- Two organs are found inside the inner ear, the function of one organ is to hear which is called Cochlea. The function of the other organ is to maintain balance which is called Vestibule. Three types of tubes are found under this vestibule which mainly work to maintain balance in the body.

Hearing process-
The process of hearing is completed by going through various stages. In this, the outer ear and the inner ear all three have an important role. These three parts of the ear play a role in the hearing process in the following way.

Outer ear- The bass ear works to collect various sounds present in the environment and sends these sounds inside the ear canal. The pinna makes the sounds of frequency of 5000-6000 Hz a little louder due to the process of resonance. The function of the ear canal is to prevent any bass object from entering the ear and this canal also increases the sounds of frequency of 2500-3000 Hz through the resonance process. The sound coming from the external environment is in acoustic energy.

Middle ear- The process of vibration in the bones converts the sound into mechanical energy. The function of the middle ear is to transmit the sound from the bass ear to the inner ear. The eardrum acts like a transformer, that is, whatever sound comes from outside to inside and hits the eardrum, then due to its structure, the eardrum makes that sound 27 decibels louder, because when the sound goes from one medium (air) to another medium (fluid), its energy gets attenuated. In this way, the middle ear fulfills this deficiency.

Inner ear – The movement of the stapes bone in and out in the oval window of the middle ear displaces the perilymph fluid present in the vestibular tube of the inner ear. This displacement exerts pressure on the Reginer’s membrane due to which the endolymph fluid present in the scala media gets displaced. In the same scala media, the organ is pressed on the vasillar membrane. Nerve impulses are generated only during depolarization and very less or not generated during hyper-polarization and the mechanical energy coming from the middle ear is converted into chemical energy in the inner ear. In this way, hair cells convert chemical energy into electrical nerve sensation and then this nerve sensation is sent to the brain through auditory nerves.

Classification of hearing Disability-

Every person’s hearing ability is different. Some people can hear loud sounds properly, some can hear low sounds, and some can hear normal sounds. We classify disability by measuring hearing ability. From time to time scientists have classified hearing disability, a detailed description of which is given below. According to the World Health Organization, hearing disability has been classified into the following six categories:

Hearing Loss Range (dB)	Classification
10–25 dB	Normal
26–40 dB	Mild
41–55 dB	Moderate
56–70 dB	Moderately Severe
71–90 dB	Serious (Severe)
91 dB and above	Profound

Normal- Under this category, the hearing power of the person is normal and there is no difficulty in hearing any kind of sound.

Mild- Under this category, a person can hear any sound like normal, but sometimes there is difficulty in hearing slow and thin sounds. Small children develop speech and language without any problem. But some start pronouncing high frequency letters incorrectly.

Moderate- In this type of hearing loss, the person has more difficulty in hearing. If he is sitting in a big hall or there is difficulty in hearing someone’s voice amidst the sound of four or five people together. In this, the development of speech and language of a small child definitely gets left behind, so special attention has to be given to him.

Moderately Severe- Here the person cannot hear easily without a hearing aid. It is necessary to use a hearing aid in a small child from the beginning, only then the development of speech and language is possible Along with this, for better speech and language development of the child, help of special speech therapy and special school can be taken.

Severe- Here also the person is completely dependent on hearing aids. Without hearing aids, he cannot hear any kind of normal sound. Even small children are completely dependent on hearing aids. Therefore, their speech and language development is completely dependent on hearing aids.

Profound- Under this category, hearing aids are the only solution for small and big people. Only through this can verbal language be communicated.