Once a person has been identified with an ear or
hearing condition, he or she can benefit from a
range of clinical, rehabilitative and environmental
interventions currently available. The nature, degree
and progression of hearing loss, along with any
underlying or accompanying health conditions (e.g.
otitis media, otosclerosis etc.), determine the clinical
profile of an individual, although people with the
same clinical profile can have very different everyday
hearing care needs (183). This is because the impact
of hearing loss depends not only on the clinical
profile, but also on contextual factors such as communication needs,
environmental factors and access to rehabilitation (10, 184, 185).


Adopting a person-centred approach is essential for determining an individual’s
hearing care and rehabilitation needs. As illustrated in Figure 2.4, person-centred
ear and hearing care involves an understanding in terms of their clinical profile,
communication needs and preferences and the resources available.

Hearing loss that accompanies ear diseases, such as
otitis media or otosclerosis, can generally be treated
through medicines or surgery (as described earlier
in section 2.2). However, the majority of hearing
loss is irreversible, and rehabilitation is required at
all stages during the life course. Rehabilitation is
essential to improve function, activity, participation
and ultimately offer a better quality of life for people
with hearing loss (186). Figure 2.5 depicts the
different approaches to rehabilitation adopted; these
include: (i) hearing technology in the form of hearing
aids, cochlear implants and implantable hearing aids;
(ii) sign language and other sensory substitution
such as Braille, Tadoma, print on palm, and speechreading;
and (iii) rehabilitative therapy, such as Total
Communication and hearing and speech therapy.


Hearing technology, to enhance or enable auditory perception, forms a key
component of hearing rehabilitation. The use of such technology gives users
increased access to information carried through sound and speech (187). Although
technology is a key part of rehabilitation, it is essential nonetheless to note that
it forms only one part of a rehabilitation strategy. The different types of hearing
technology include hearing aids and implants as described below.


Hearing aids (186, 188–191) are a noninvasive, low-risk and effective option most
frequently used to rehabilitate hearing loss (192). (The different types of hearing
aid are described in Box 2.9 below.) The vast majority of people with hearing loss
are adults who experience mild to moderate degrees that pose difficulties in their
day-to-day life. This level of hearing loss can be well addressed through the use of
hearing aids that improve quality of life and listening ability. Even in cases of people
with severe hearing loss, those with cognitive impairments (193), and in children
(194, 195), hearing aid use can improve the ability to perceive sensory inputs and
functional outcomes. These functional outcomes, however, are not merely the result
of hearing amplification, but depend on other supportive interventions and factors.


Cochlear implants are electronic devices, especially
useful when a conventional hearing aid has little or
no benefit or cannot be used (192). Typically, these
devices bypass the middle- and inner-ear structures
to stimulate the auditory nerve directly (197), and
can give a deaf person a useful representation of
sounds in the environment, making it possible to
understand speech. A description of how a cochlear
implant works is provided in Box 2.10 and illustrated
in Figure 2.6.
Their use in children with severe degree of hearing loss
has brought substantial benefits to those implanted, and when accompanied by
proper rehabilitation they lead to significant improvement in audiological status,
overall functioning and speech perception skills (198). Children with cochlear implants
have greater likelihood of acquiring oral language, integrating into regular schools and
being able to experience sounds along with better speech skills (199, 200). Cochlear
implants can also have a beneficial impact on learning and educational outcomes
as well as the overall quality of life, though many factors other than implantation
influence these results (201–203). In recent years, the scope of implantation has been
expanded to adults with severe to profound sensorineural hearing loss, who show
improved speech perception and health-related quality of life with their use (202, 204).

While cochlear implants present remarkable potential in terms of their availability and the opportunities
they create, their use is limited for many conditions and individuals (205–207). In addition, the need for
rehabilitation therapy and support services that must accompany cochlear implantation can be substantial.
Cochlear implantation must therefore be undertaken only after thorough clinical evaluation to ensure
the potential benefits, and only where supportive infrastructure for rehabilitation therapy exists.


Bone conduction and middle ear implants represent another growing area of
technological advancement in the field of hearing rehabilitation (209–212).
• Bone conduction implants transmit sound to the inner ear through the bones
of the skull, bypassing the middle ear.
• Active middle ear implants may be fully or partially implanted in the ear. They
function by converting sound into kinetic energy which directly vibrates the middle
ear ossicles or transmits the vibrations to the inner ear.
All individuals with conductive, sensorineural or mixed types of hearing loss can
potentially use these aids; they do not require the external ear canal to be blocked
and thereby reduce many of the problems associated with conventional hearing
aids (e.g. wax impaction). The implants are also effective in those with middle-ear
diseases and external ear malformations.
Whatever the technology used, complementary measures are necessary to ensure
that these devices and implants benefit their users. As illustrated in Figure 2.7, this
is achieved through a person-centred approach to care which involves the provision
of: (186, 187)

Instruction in the use of hearing devices and accessories which increases
the possibility of a positive outcome from their use.
• Auditory and cognitive training to help people better use their enhanced
hearing in all situations.
• Counselling to target issues of participation and quality of life that result from
residual deficits of function and activity.

• In children, timely intervention with hearing aids
and implants leads to better hearing, spoken
communication and quality of life, which further
translates into better educational outcomes (202,
203, 213–215). The use of hearing aids can also
protect against cognitive decline and dementia
• In adults, the use of hearing aids and cochlear
implants improves listening abilities and quality of life (186, 187, 190, 191,
193, 202, 214, 217).
• The use of these devices is shown to be cost–effective
in different economic
settings (202, 214, 215, 218–220).
WHO made a conservative estimation of return on investment in unilateral
hearing aids and cochlear implants in children. In terms of unilateral hearing aids,
estimations based on actual costs in a high-income setting showed a possible return
of 1.84 International dollars for every 1 dollar invested, and a lifetime value of DALYs
averted of 60 183 dollars for each individual. In the example of a lower-middleincome
setting, the return on investment ratio was 1.62 with a lifetime value of
DALYs averted of 3564 dollars.
With unilateral cochlear implants, estimations based on actual costs in a high-income
setting showed a return of 2.59 International dollars for every 1 dollar invested,
and a lifetime value of DALYs averted of 38 153 dollars for each individual. In the
example of a lower-middle-income setting, the return on investment ratio was
1.46 International dollars with a lifetime value of DALYs averted of 6907 dollars. For
an upper-middle-income setting, the return on investment ratio was estimated to
be 4.09 International dollars with a lifetime value of DALYs averted of 24 161 dollars.
Further details are provided in WEB ANNEX B.
Despite the effectiveness and cost–
effectiveness of hearing amplification in
rehabilitation, many challenges restrict their use and accessibility. These challenges
and potential solutions to address their non-availability and non-use are outlined
in Section 3. Nonetheless, game-changing developments, especially targeting
adult-onset hearing loss provide a sound foundation for further improvements to
accessing hearing technology and hearing-related services.


In recent years, the many developments in the field of hearing technology, its
provision and related policies, offer the potential to expand access to the required
devices in underserved populations. Examples of these include:
• Developments in technology
i. Self-fitting hearing aids/trainable hearing aids:
These aids have the potential to address accessibility and affordability of
hearing health care, particularly in low- and middle-income countries (222–225),
by reducing the need for audiological support and equipment. A self-fitting
hearing aid enables the user to perform both threshold measurements and
fine-tuning, with the help of detailed instructions (222). Studies suggest that
self-fitting of hearing aids is feasible and is more likely to be successful if the
devices and interfaces are clear and well designed, and if the fitting process
is clearly outlined (222, 223, 225). However, research that targets diverse
population groups and educational settings is required.

language can ensure cognitive development and facilitate communication. It
also enables children to gain education through sign language and have proper
socioemotional development.
ii. who live in environments with access to hearing technology and speech learning.
While taking steps to ensure that a child develops spoken language skills, learning
sign language ensures that infants do not face any delay in language acquisition.
Given the far-reaching consequences of linguistic deprivation in early childhood,
it is essential to address this at the earliest stage possible. Sign language provides
that possibility. Moreover, learning sign language does not hinder or delay the
subsequent or simultaneous acquisition of spoken language skills.
iii. whose families prefer to use non-auditory communication through sign language
instead of, or in addition to, auditory-verbal rehabilitation.
Speech reading, where a person understands spoken
language solely by viewing the person talking, forms
an important means of accessing communication for
those with hearing loss. The underlying neurological
processes are similar to those for auditory word
recognition (246). Lipreading is one of the most
common means of speech reading and includes
looking at teeth, tongue, facial expressions, body
language and other visual cues to understand what
a person is saying. This is an integral part of speech
perception (247) and, since it requires training, needs
to be considered in hearing and speech rehabilitation
strategies (248). Such training should further be
supported by auditory training and use of cued
speech (248).
Alternative methods of communicating are especially useful for people with dual
sensory loss such as deaf-blindness, where access to communication is further
challenged. Such methods include:
“Signed languages are natural human
languages existing across numerous
societies around the world. As with spoken
languages, signed languages display
phonetic, phonemic, syllabic, morphological,
syntactic, discourse, and pragmatic levels of
organization as expected of natural languages.”
(241, 245)
• Signing: includes signed communication, signed supported languages, manually
coded languages (e.g. Signed Supported English), Total Communication,
Simultaneous Communication and Cued Speech. All are terms that cover
communication where a spoken language is used with some visual support or cues.
• Finger spelling: involves spelling out words by finger shapes on the hand and
can be used to support oral approaches.
• Braille: is a form of written language in which characters are represented by
patterns of raised dots that are felt with the fingertips.
• Tadoma: involves the deaf-blind individual placing their thumb on the speaker’s lips and
their fingers along the jawline to feel the movements of the speaker as they talk (249).


In addition to rehabilitation, hearing assistive technology is useful in improving access
to communication. By improving sound quality and speech discrimination, it supports
a person’s interaction with the environment. Hearing assistive technology includes
both software and hardware that can be used in a variety of environments, including
home, work, school, social gatherings, meetings, hospitals, places of worship, and
theatres. The different types of hearing assistive technologies available include
devices for enhanced listening that improve the signal to noise ratio for improved
listening in a noisy surrounding; alerting devices; and telecommunication devices.
These devices enhance the use of hearing aids and cochlear implants, and can also
assist those not using these tools. The speaker talks into a microphone and the
sound is delivered directly into a receiver worn by the listener or integrated within
his or her hearing aid or implant. By doing so, the system cuts off interference and
masks the effects of environmental background noise, making speech easier to
understand. Its use improves a person’s ability to listen and therefore is useful in
classroom settings. The system also makes it easier for people with hearing loss
to carry out conversations in public spaces, health-care centres and in their home.

The common technologies used in enhanced listening devices include:
• Frequency modulation (FM) systems (217) – which convert sound into FM
signals (see Figure 2.8).
• Infrared system (278–280) – which uses infrared rays to transmit sound.
• Hearing induction loop (281) – which transmits an audio signal directly into a
hearing aid via a magnetic field.
• Hardwired system (282) – where sound is carried from the microphone to the
receiver through a wired connection.
Figure 2.8 A frequency modulation system

A frequency modulation (FM) system typically has two or more components: the
microphone, with or without a transmitter; and a receiver attached to the hearing aid or
microphone. FM serves well in eliminating the effects of background noise and maintaining
a constant speech input, irrespective of distance between speaker and listener.
Alerting devices use sound, light, vibrations, or a combination of these, to catch the
attention of a person who is hard of hearing or deaf. Examples of alerting devices
include shaking alarms, pillow vibrators, bed vibrator, vibrating pagers, wrist vibrator,
vibrating and shaking alarm clocks, motion signaller, motion signaller, fire and smoke
signaller, and doorbell signaller (283).

Telecommunication devices transmit spoken messages in a written format. Examples
include: (i) a teleprinter that works as a two-way typing telephone where someone
types the message and responds to the teleconversation; and (ii) a captioned
telephone where spoken words are converted into text.


Hearing assistive services include measures such as captioning and sign
language interpretation.
Captioning is the process of converting the audio content of a television broadcast,
webcast, film, video, CD-ROM, DVD, live event, or other productions into text, and
displaying the text on a screen, monitor, or other visual display system (284). It is an
important means of providing access to content for people with hearing loss who
rely mainly on oral communication. Captions not only display words as the textual
equivalent of spoken dialogue or narration, they also include speaker identification,

sound effects, and music description. Further information on captioning is provided
in Box 2.13. Captioning typically is offered for:
• Live events that are held face to face, e.g. meetings, conferences, theatre
performances or events streamed online such as webcasts, live social media
events, television programmes.
• Pre-recorded content such as movies, television, video and audio material.

Sign language interpretation is the use of a sign language to convey the information
contained in the programme audio (speech and other important sounds) to viewers
who are deaf, and for whom sign language is their preferred language; it requires
an interpreter who can translate the audible content into a sign language that is
understood by the participants. Sign languages differ from country to country. Use
of sign language interpretation services in health-care settings facilitates access to
health services among sign language users (287), and can also improve classroom
learning among deaf students (288). The provision of such services in countries is
required by Article 9 of the United Nations Convention on the Rights of Persons with
Disability (289). An example of the value of sign language interpretation to education
and health is provided in Box 2.14.

Well-established, effective and evidence-based interventions, along with more recent
developments, provide a range of options to address hearing loss across the life
course. Sections 3 and 4 outline solutions to the challenges faced in using a public
health approach, and in making these options accessible to all those in need.


While there are many solutions designed for the individual with hearing loss,
improving the acoustic environment can reduce hearing-related disability and
increase accessibility to sound and communication. This is important across the life
course in different settings: in learning situations, such as classrooms; in social and
cultural environments where communication is highly valued (including restaurants,
church and activity halls, adult care homes), and in environments of daily living, such
as supermarkets. Good acoustics are critical to learning for young children who have
less well-developed phonological knowledge of the world than adults, and are thus
less able to reconstruct degraded speech information (292). Unsuitable acoustics
present an even greater challenge for children with hearing loss or learning problems
(292). Open plan learning is becoming increasingly popular in some settings to
enhance flexible teaching and learning practices; however, acoustic modifications
to support this have often been overlooked, leading to poor perception of auditory
information (293).
For older adults with hearing loss, listening in challenging environments increases
cognitive effort which is associated with fatigue and social withdrawal (294, 295).
Many restaurant and café dining areas are noisy, in part due to a lack of soft
furnishings which increases acoustic reverberation (296). Universal building design16
maximizes accessibility (297) and benefits older adults; the principles of universal
design are recommended in WHO’s Age Friendly Cities initiative (298). There is a
growing interest in “soundscapes” in urban design; this concept considers the sound
environment in combination with the human experience and behavioural response
to it, rather than the noise level of the setting alone (299). The Positive Soundscape
Project (300) included older adults, and adults with hearing loss in the co-design of
such spaces.