Deafness is a partial or complete loss of hearing. It may occur at birth or as the result of hearing loss at any stage throughout life.

Key points 

  1. Deafness can occur as a result of illness, accident, over-exposure to noise, drugs and medication, trauma, genetics or simply getting older. You may be born with deafness or it may occur at any stage of life.
  2. Deafness is measured by categories of mild, moderate, severe or profound hearing loss. This page focuses on severe and profound deafness. You can read more about hearing loss in adults and hearing loss in babies and children.
  3. People who identify with the Deaf community generally regard this as a language and cultural identity rather than a disability. 
  4. People who have been deaf since birth or early childhood are likely to identify as members of a Deaf community and generally use New Zealand Sign Language as their preferred means of communication.
  5. Hearing impaired people who become deaf later in life and some other deaf people can speak and lip read. 
  6. NZSL users typically access appointments with public service providers through NZSL interpreters. NZSL users have various levels of literacy as childhood deafness affects the development of childhood literacy.

(Image sourced from NZSL Dictionary – Deaf Studies Research Unit)

What are the causes of deafness?

Hearing loss at birth is known as congenital hearing loss, while hearing loss that occurs after birth is called acquired hearing loss.

Congenital hearing loss

Some of the many causes of congenital deafness include the following: 

  • Hereditary disorders – this means parents pass on affected genes to their children. In most cases, hereditary hearing loss is caused by malformations of the inner ear.
  • Genetic disorders – genetic mutations may happen, for example, at the moment of conception. Some of the genetic disorders that can cause deafness include osteogenesis imperfecta, Trisomy 13 (Patau syndrome) and Treacher Collins syndrome.
  • Prenatal exposure to disease – a baby will be born deaf or with hearing problems if they are exposed to certain diseases in utero, including rubella (German measles), influenza and mumps. Other factors that are thought to cause congenital deafness include exposure to methylmercury and medications such as quinine.

Acquired hearing loss

Acquired hearing loss from other causes throughout life may also lead to severe or profound deafness. These include noise-related hearing loss, illness, accident or trauma and aging-related hearing loss. See hearing loss in adults for more information.

What are the symptoms of deafness?

Hearing loss is measured in decibels hearing loss (dB HL). It can be graded as follows:

  • 20-40 dB HL: mild, cannot hear whispers.
  • 41-70 dB HL: moderate, cannot hear conversational speech.
  • 71-95 dB HL: severe, cannot hear shouting.
  • >95 dB HL: profound, cannot hear sounds that would be painful to listen to for a hearing person.

Read more about the symptoms of hearing loss in adults and hearing loss in babies and children.

How is deafness diagnosed?

Audiologists carry out tests to assess your level of hearing. They begin by examining your ear canal with an otoscope. This helps them identify any temporary problems that may affect your hearing, such as build-up of ear wax or a burst eardrum.

You then wear headphones to do a tone test, where you listen to beeps at different pitches. The beeps get quieter until you no longer hear them.

Your cochlear (inner ear) may also be tested and you may be given a speech test to check you understand the sounds of speech. Read more about hearing tests for adults.

How is deafness treated?

Some deafness is treated with the use of hearing aids. Hearing aids are most effective at helping mild, moderate or severe hearing loss caused by conductive hearing loss or reduced sensory hearing loss.

Hearing aids are usually not as effective as cochlear implants for assisting very severe or profound hearing losses.

Hearing aids can also provide some benefit for hearing problems caused by damage to the hearing nerve or brain.

People who have lifelong severe or profound deafness may identify socially as Deaf. In Aotearoa, members of the Deaf community use New Zealand Sign Language to communicate and they are less likely to see treatment for deafness. Find out more about NZ Sign Language.

What support is available with deafness?

Deaf Aotearoa A national organisation representing Deaf people (primarily NZ Sign Language users), and the national service provider for Deaf people in New Zealand
Hauora Deaf Aotearoa’s service for Deaf and hard-of-hearing people that provides needs assessment and coordination, applications for assistive equipment and information and advice
National Foundation for the Deaf This national organisation promotes the interests of over 880,350 New Zealanders who are deaf or hard of hearing
Equipment for people who are Deaf or have hearing loss Ministry of Health, NZ, 2018
Cochlear implants Ministry of Health, NZ, 2018
Guide to getting hearing aids – hearing aid funding scheme Ministry of Health, NZ, 2018
Guide to getting hearing aids – hearing aid subsidy scheme  Ministry of Health, NZ, 2018
Deafness support groups Health Navigator, NZ, 2018 

Learn more

The following links provide further information about deafness. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

Hearing problems Patient Info, UK, 2016
Deaf awareness courses Deaf Aotearoa, NZ Provides training to businesses and organisations about Deaf culture, the Deaf community and overcoming communication barriers with Deaf clients, ensuring all customers receive a positive experience.
First Signs Supports the learning of New Zealand Sign Language for family and whānau of Deaf or hard-of-hearing children aged 0–5 years.


  1. Deafness – a range of causes Better Health Australia, 2017
  2. Deafness in adults Patient Info, UK, 2014
  3. About hearing aids NZ Audiology Society, 2011

Reviewed by

Dr Rachel McKee is the programme director for New Zealand Sign Language Studies at Victoria University of Wellington. She has 25 years’ experience interpreting, teaching and researching in the field of NZ Sign Language and Deaf Studies.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Rachel McKee and Joanne Wikto Last reviewed: 24 Sep 2018