Deaf and Hard of Hearing (DHH)

Blindness separates you from objects, Sound separates you from people

- Helen Keller, who was deafblind

The problems of deafness are deeper and more complex, if not more important, than those of blindness. Deafness is a much worse misfortune. For it means the loss of the most vital stimulus - the sound of the voice that brings language, sets thoughts astir and keeps us in the intellectual company of man.

Deaf & Hard of Hearing (DHH)

The Deaf & Hard of Hearing Section of the DEEPAK: NDLI Disability Knowledge Portal presents extensive information on all aspects of the life of persons with deafness or hearing impairment. This is divided into eight subsections (detailed below). The focus has been kept on Education, Employment, and Training through first three subsections. Caregiving including support services and Institutions dealing with blindness are covered next. Assistive Technology and Android & iOS Apps have become critical assistance in all the activities. These are covered in the following two subsections. Last but not the least, the story of few Achievers, who have excelled in spite of all odds of disability and attitude of the society at large are chronicled as a documentation for achievements of human will.

While the portal is primarily designed for persons with deafness or hearing impairment in India, it does cover a lot of information in respect of science, technology, history, and practices that are agnostic to geographic and political boundary.

How do we hear?

Hearing Loss

Deafness is an invisible disability

Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken language, and in adults it can create difficulties with social interaction and at work. Hearing loss can be temporary or permanent.

Hearing loss related to age usually affects both ears and is due to cochlear hair cell loss. In some people, particularly older people, hearing loss can result in loneliness. Deaf people usually have little to no hearing.

Hearing loss may be caused by a number of factors, including: genetics, ageing, exposure to noise, some infections, birth complications, trauma to the ear, and certain medications or toxins. A common condition that results in hearing loss is chronic ear infections. Certain infections during pregnancy, such as cytomegalovirus, syphilis and rubella, may also cause hearing loss in the child.

Hearing loss is diagnosed when hearing testing finds that a person is unable to hear 25 decibels in at least one ear. Testing for poor hearing is recommended for all newborns. Hearing loss can be categorized as mild (25-40 dB), moderate (41-55 dB), moderate-severe (56-70 dB), severe (71-90 dB), or profound (> 90 dB).

Types of hearing loss

The type of hearing loss is usually determined by where the issue arises anatomically in the ear (inner, middle or outer ear). There are three categories commonly used to distinguish hearing loss by origin:

  • Conductive Hearing Loss refers to hearing loss that arises because sound cannot get through the outer or middle ear. This type of hearing loss can, among other reasons, be caused by fluid, earwax or an infection in the ear. It is often temporary and can sometimes be treated with medicine or surgery.

  • Sensorineural Hearing Loss comes from issues with the inner ear. This type of hearing loss is usually permanent. Age, noise and genetics are common reasons for sensorineural hearing loss.

  • Mixed Hearing Loss is a combination of conductive as well as sensorineural hearing loss.


About half of hearing loss globally is preventable through public health measures. Such practices include immunization, proper care around pregnancy, avoiding loud noise, and avoiding certain medications. The World Health Organization recommends that young people limit exposure to loud sounds and the use of personal audio players to an hour a day in an effort to limit exposure to noise.

Remedial Measures

Early identification and support are particularly important in children. For many, hearing aids, sign language, cochlear implants and subtitles are useful. Lip reading is another useful skill some develop. Access to hearing aids, however, is limited in many areas of the world.

Source: Hearing loss, Wikipedia

Models of Deafness

The model through which the deaf person is viewed can impact how they are treated as well as their own self perception. There are three models of deafness rooted in either social or biological sciences. These are

  • Cultural Model: Deaf belong to a culture in which they are neither infirm nor disabled, but rather have their own fully grammatical and natural language.

  • Social Model: The social model seeks to explain difficulties experienced by deaf individuals that are due to their environment.

  • Medical (or Infirmity) Model: Here deafness is viewed undesirable, and it is to the advantage of the individual as well as society as a whole to "cure" this condition.

Source: Models of Deafness, Wikipedia

International Symbol for Deafness

Hearing Test

A hearing testing provides an evaluation of the sensitivity of a person's sense of hearing and is most often performed by an audiologist using an audiometer. An audiometer is used to determine a person's hearing sensitivity at different frequencies. There are other hearing tests like Weber test and Rinne test.

Hearing Loss Categories

Hearing loss is diagnosed when hearing testing finds that a person is unable to hear 25 decibels in at least one ear.

Hearing loss is categorized as:

  • Mild (25 to 40 dB)

  • Moderate (41 to 55 dB)

  • Moderate-severe (56 to 70 dB)

  • Severe (71 to 90 dB)

  • Profound (greater than 90 dB)

Ten facts about hearing loss you should know

Fact 1: There are around 360 million people with disabling hearing loss.

Fact 2: Unaddressed hearing loss poses a global cost of $750 billion international dollars.

Fact 3: Thirty-two million children have disabling hearing loss.

Fact 4: Chronic ear infections are the leading cause of hearing loss.

Fact 5: Nearly one in every three people over 65 years are affected by disabling hearing loss.

Fact 6: Noise is a major avoidable cause of hearing loss.

Fact 7: Hearing loss can be caused by occupational noise and the use ototoxic medications.

Fact 8: People with hearing loss can benefit from devices such as hearing aids and cochlear implants.

Fact 9: Sign language and captioning services facilitate communication with people who are deaf and hard of hearing.

Fact 10: Sixty per cent of childhood hearing loss is preventable through public health actions.

Key facts from WHO

  • By 2050 nearly 2.5 billion people are projected to have some degree of hearing loss and at least 700 million will require hearing rehabilitation.

  • Over 1 billion young adults are at risk of permanent, avoidable hearing loss due to unsafe listening practices.

  • An annual additional investment of less than US$ 1.40 per person is needed to scale up ear and hearing care services globally.

  • Over a 10-year period, this promises a return of nearly US$ 16 for every US dollar invested.

Over 5% of the world’s population – or 430 million people – require rehabilitation to address their ‘disabling’ hearing loss (432 million adults and 34 million children). It is estimated that by 2050 over 700 million people – or one in every ten people – will have disabling hearing loss.

‘Disabling’ hearing loss refers to hearing loss greater than 35 decibels (dB) in the better hearing ear. Nearly 80% of people with disabling hearing loss live in low- and middle-income countries. The prevalence of hearing loss increases with age, among those older than 60 years, over 25% are affected by disabling hearing loss.

Hearing loss and deafness

A person who is not able to hear as well as someone with normal hearing – hearing thresholds of 20 dB or better in both ears – is said to have hearing loss. Hearing loss may be mild, moderate, severe, or profound. It can affect one ear or both ears, and leads to difficulty in hearing conversational speech or loud sounds.

'Hard of hearing' refers to people with hearing loss ranging from mild to severe. People who are hard of hearing usually communicate through spoken language and can benefit from hearing aids, cochlear implants, and other assistive devices as well as captioning.

'Deaf' people mostly have profound hearing loss, which implies very little or no hearing. They often use sign language for communication.

Causes of hearing loss and deafness

Although these factors can be encountered at different periods across the life span, individuals are most susceptible to their effects during critical periods in life.

Prenatal Period

  • Genetic factors - Include hereditary and non-hereditary hearing loss

  • Intrauterine infections – such as rubella and cytomegalovirus infection

Perinatal period

  • Birth asphyxia (a lack of oxygen at the time of birth

  • Hyperbilirubinemia (severe jaundice in the neonatal period)

  • Low-birth weight

  • Other perinatal morbidities and their management

Childhood and adolescence

  • Chronic ear infections (chronic suppurative otitis media)

  • Collection of fluid in the ear (chronic nonsuppurative otitis media)

  • Meningitis and other infections

Adulthood and older age

  • Chronic diseases

  • Smoking

  • Otosclerosis

  • Age-related sensorineural degeneration

  • Sudden sensorineural hearing loss

Factors across the life span

  • Cerumen impaction (impacted ear wax)

  • Trauma to the ear or head

  • Loud noise/loud sounds

  • Ototoxic medicines

  • Work related ototoxic chemicals

  • Nutritional deficiencies

  • Viral infections and other ear conditions

  • Delayed onset or progressive genetic hearing loss

The impact of unaddressed hearing loss

When unaddressed, hearing loss impacts many aspects of life at individual level:

  • Communication and speech

  • Cognition

  • Education and Employment

    • In developing countries, children with hearing loss and deafness often do not receive schooling. Adults with hearing loss also have a much higher unemployment rate. Among those who are employed, a higher percentage of people with hearing loss are in the lower grades of employment compared with the general workforce.

Social isolation, loneliness and stigma

Impact on society and economy