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Assistive Technology for Hearing

Original Editor - Ewa Jaraczewska based on the course by Marike Venter

Top Contributors - Lucinda hampton, Jess Bell, Ewa Jaraczewska, Kim Jackson, Naomi O'Reilly, Angeliki Chorti and Mohamed A Hassanin  

Introduction

Hearing is essential for communication, environmental awareness, social engagement, and safe movement. It supports speech recognition, language development, emotional expression, and cognitive health. Loss of hearing can significantly impact a person’s ability to participate in daily activities and affect their overall quality of life.[1]

Globally, over 430 million people, including 34 million children, require rehabilitation to address disabling hearing loss. This figure is expected to rise to over 700 million by 2050, or one in ten people worldwide. The World Health Organization defines disabling hearing loss as a hearing loss greater than 35 decibels (dB) in the better-hearing ear.[2] The prevalence increases with age, and more than 25% of people aged over 60 years are affected. Nearly 80% of those affected live in low- and middle-income countries.[2]

Hearing loss can result in social isolation, depression, cognitive decline, and an increased risk of dementia. Despite the availability of interventions, only a fifth of individuals who would benefit from hearing aids actually use them.[3]

This article explores hearing loss, its types, causes, assessment, assistive technologies, and the audiologist’s role in rehabilitation.

The Role of Hearing

Hearing (audition) allows humans to recognise, interpret, and respond to spoken language and environmental cues. It plays a vital role in:

  • social communication and emotional connection
  • language comprehension and speech production
  • environmental awareness and safety
  • emotional and cognitive well-being

Auditory input helps regulate volume control in communication, and in some contexts, auditory cues are more effective than visual cues for interpreting emotion or intent.[3]

These hearing-related abilities significantly impact social participation, mental well-being, and physical and cognitive health.[4]

Physiology of Hearing

Figure 1. Ear Anatomy.

The human ear, a paired organ, changes physical vibrations (sound) into nerve impulses that are processed by the brain's central auditory pathway. Each ear contains a snail-shaped, coiled structure called the cochlea, the primary sense organ for hearing. Structurally and functionally, the ear is divided into three parts necessary for normal hearing:

  • the outer ear, which collects sound waves
  • the middle ear, which includes the eardrum and three bones (malleus, incus, and stapes) - these bones amplify sound waves and transmit them from the outer to the inner ear[5]
  • the inner ear, which contains the cochlea and the vestibular labyrinth

Within the cochlea, delicate hair cells are responsible for transducing sound vibrations into electrical signals.[6] Normal human hearing ranges from around 20 to 20,000 Hz.[7]

If you would like to learn more about ear anatomy, please see: Hearing in the Elderly.

Hearing Loss

"Hearing loss, the most common form of human sensory deficit, is the partial or total inability to hear sound in one or both ears."[8]

Hearing loss can be defined based on its underlying cause, severity, and anatomical location within the auditory pathway. There are three types of hearing loss[9]:

  • conductive
  • sensorineural
  • mixed type loss

The severity of the hearing loss is categorised based on the decibel (dB) level of hearing thresholds at individual frequencies. Hearing loss can be classified as mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB), or profound (greater than 91 dB).[8]

Conductive Hearing Loss

Figure 2. Conductive Hearing Loss.

Conductive hearing loss (CHL) occurs when there is a disruption in the transmission of sound waves through the outer or middle ear to the inner ear. It can affect all frequency ranges (Figure 2).[8] The obstruction typically occurs in the outer or middle ear and may be caused by:

  • blockage of the external auditory canal (e.g. impacted cerumen)
  • middle ear infections (e.g. otitis media)
  • damage to middle ear structures (e.g. ossicular chain disruption)
  • congenital abnormalities of the outer or middle ear

These pathologies reduce the mechanical efficiency of sound conduction. Management of CHL requires a comprehensive understanding of the individual’s anatomical and developmental context. Depending on the underlying cause, treatment may include pharmacological therapy, surgical correction, or the use of hearing aids.[9]

Sensorineural Hearing Loss

Figure 3. Sensorineural Hearing Loss.

Sensorineural hearing loss (SNHL) can cause complete hearing loss. It can result from damage to the inner ear, specifically the hair cells of the cochlea, or the auditory nerve (Figure 3).[9]

Causes of SNHL include:[8]

  • ageing (presbycusis)
  • noise exposure (e.g., explosions, fireworks, gunfire, loud music)
  • genetic predisposition
  • ototoxic medications (e.g. aminoglycosides, chemotherapeutic agents)
  • perinatal infections (rubella, herpes, toxoplasmosis, syphilis, cytomegalovirus)
  • birth complications (e.g. asphyxia and low birth weight)

SNHL is often irreversible, but can be managed with hearing aids, cochlear implants, and auditory rehabilitation to enhance communication and quality of life.[9]

Mixed Type Hearing Loss

Figure 4. Mixed Hearing Loss.

Mixed hearing loss is a complex condition caused by damage to the inner ear (sensorineural) and the outer or middle ear (conductive) (Figure 4). This combination typically results in greater hearing impairment than either conductive or sensorineural hearing loss alone.

Several factors can contribute to mixed hearing loss, including:[10]

  • age-related hearing loss combined with an earwax blockage
  • noise-induced hearing loss alongside an ear infection
  • ototoxicity due to chemotherapy combined with fluid accumulation due to seasonal allergies

Treatment for mixed hearing loss depends on the specific causes. While the conductive component may be treatable with medical or surgical interventions, the sensorineural component is more difficult to manage. Treatment approaches often include a combination of medical, surgical, and rehabilitative interventions tailored to the individual's needs.[9]

Function and Hearing Loss

Early-onset hearing loss before two years of age can significantly impact a child's spoken language development, reading ability, and educational achievements.

Gradual hearing loss from age-related changes or noise exposure impacts functional hearing rather than other cognitive skills initially.[11] However, untreated hearing loss can have flow-on effects, including social isolation and eventual cognitive decline.[12] [13] Because hearing loss can affect communication and environmental awareness, it can have various psychosocial impacts, including interpersonal challenges, loneliness, depression, difficulty performing daily activities, and reduced quality of life.[14] There is also a link between untreated hearing loss and an increased risk of dementia.[15] Moderate or greater hearing loss is associated with functional difficulties and a faster decline in function, particularly balance, gait speed and walking endurance.[16]

The Role of the Audiologist in Hearing Loss

Various healthcare professionals, including physicians, nurses, speech and language therapists (pathologists), audiologists and technicians, can conduct hearing screening with automated devices. However, only audiologists can conduct a diagnostic hearing assessment, which includes analysing, interpreting, and reporting test results.[17]

The audiologist identifies / evaluates the level of hearing loss and guides patients to improve their hearing through the following:[18]

  • personalised advice based on the patient's needs and preferences through:
    • understanding the impact of hearing loss on daily functioning[19]
    • addressing coexisting conditions, such as balance disorders or cognitive impairments[19]
  • selecting and fitting appropriate assistive technology for hearing
  • providing counselling to help the person adjust to changes in their auditory capabilities
  • monitoring changes over time, tracking the progression of hearing loss and adjusting treatment as needed[19]

Audiology Assessment

The following sections discuss key aspects of audiology assessment, which includes a range of behavioural and objective measurements.[19]

Behavioural Measurements

Pure tone testing is the gold standard audiological assessment. This behavioural measurement includes air and bone conduction tests to identify the type of hearing loss. Air and bone conduction thresholds are compared to pinpoint the location of the pathology. This information guides the audiologist in creating a tailored treatment plan, including medical intervention, hearing aids, cochlear implants, or other rehabilitative strategies.[9]

Air Conduction Tests

Air conduction tests evaluate the functionality of the auditory system, including the outer, middle, and inner ear. Pure tone stimuli are presented through headphones or insert earphones, and the patient is asked to respond to stimuli at different intensities and frequencies. This test provides information on the overall sensitivity of the auditory system and the results help determine the degree and configuration of hearing loss.[9]

Bone Conduction Tests

Bone conduction tests evaluate the integrity of the cochlea, bypassing the outer and middle ear. A bone conduction oscillator is placed on the mastoid bone behind the ear. It sends vibrations through the skull directly to the cochlea via bone conduction.

Test interpretation: normal bone conduction and elevated air conduction thresholds indicate conductive hearing loss. When a similar amount of elevation occurs between bone and air conduction thresholds, it suggests a sensorineural hearing loss. A gap between air and bone conduction thresholds might indicate a hearing loss involving both conductive and sensorineural components, but bone conduction thresholds would also be elevated.[9]

Audiogram

An audiogram is a graphical representation of a person's hearing ability across various frequencies (high-pitched versus low-pitched sounds) and intensities (loudness). The audiogram is used to assess hearing abilities, diagnose hearing loss, and determine the appropriate course of treatment or intervention.[9]

Objective Tests

Objective tests can help to evaluate hearing in individuals who may not be able to provide reliable behavioural responses, including infants, young children, and those with cognitive impairments or intellectual disabilities. This type of hearing assessment can confirm behavioural test results or be used as a separate assessment. Objective measures can provide evidence of cochlear or neural dysfunction, which helps support a diagnosis of hearing loss and enhances the overall reliability of the assessment process.[9] Examples of objective tests include: auditory brainstem response testing and otoacoustic emissions.

If you would like to learn more about an audiology assessment for hearing loss, please watch the following video:

[20]

Assistive Technology for Hearing

Audiologists work closely with patients when selecting and fitting hearing devices, considering each person's hearing needs, the type and severity of hearing loss, and lifestyle preferences. Each amplification strategy offers distinct advantages and limitations. Audiologists also provide counselling and support throughout the fitting and adjustment process to ensure the best possible outcomes for the individual.[9]

Role of Amplification Strategies in Hearing Loss

As mentioned, there is a link between hearing loss, cognition and the risk of dementia in older adults.[21][22][23] The cognitive load of processing auditory information is higher for those experiencing hearing loss. Factors associated with hearing loss that increase cognitive load include difficulty blocking background noise, distinguishing speech sounds, and following conversations.

Amplification strategies can reduce this cognitive load and may reduce cognitive changes in older adult populations at risk for cognitive decline.[23]

An individual's acceptance or rejection of hearing amplification depends on audiological and non-audiological factors.

Audiological factors include hearing sensitivity and severity of hearing loss. Key audiological factors that influence a person's acceptance of hearing aids include: a high degree of hearing loss, the person's awareness of their condition, and daily device use.[24] Common reasons for rejecting hearing aids include a lack of perceived benefit or discomfort when using the device.

Various non-audiological factors can influence hearing aid uptake. People living in urban settings are more likely to access hearing aids than those in rural settings. Social pressure and stigma can be a significant challenge for users.[25] [26] Access to financial support and insufficient income are also major influences.[24]

Direct-to-consumer devices, such as over-the-counter hearing aids, can, in theory, increase accessibility and affordability for individuals with mild to moderate loss who have no red flags and do not require other hearing-related medical interventions.[9]

However, professional guidance from healthcare professionals, such as audiologists or otolaryngologists can help users identify underlying medical conditions causing the hearing loss, ensuring optimal treatment and management.

"In my opinion, patients using over-the-counter devices may miss the opportunity to access medical intervention or more appropriate types of amplification. Fitting an over-the-counter device with professional guidance can help users navigate this self-fitting process." -- Marike Venter, Communication Pathologist and Audiologist[9]

Types of Amplification Strategies

Amplification strategies, including hearing aids, bone conduction devices, cochlear implants, and middle ear implants, help address problems related to hearing loss.

Figure 5. Types of Hearing Aids.
Hearing Aids

Hearing aids amplify sounds for people with mild to severe hearing loss.

The following types of hearing aids are available. Each type offers different features and varying levels of discretion (Figure 5):[9]

  • behind-the-ear
  • receiver-in-the-canal
  • completely-in-the-canal

Audiologists program hearing aids using specialised software and the patient's audiogram to set gain levels, adjust noise reduction and feedback suppression, and enable other features. Many hearing aids now include advanced features such as Bluetooth® streaming, AuraCast™, and artificial intelligence protocols for noise management.[9]

Figure 6. Bone Conduction Hearing Aid.
Bone Conduction Hearing Devices

Bone conduction hearing aids treat conductive loss, mixed loss, and single-sided deafness in cases where traditional air conduction hearing aids may be less effective.[9] They convert sound energy into skull vibrations (Figure 6).[27] Bone conduction hearing aids are usually surgically implanted and connected using an abutment or magnet beneath the skin. They can also be worn externally using a headband, soft band, or adhesive adapter.

Figure 7. Cochlear Implant.
Cochlear Implants

Cochlear implants provide a solution for auditory rehabilitation when conventional hearing aids prove insufficient.[28] These are surgically implanted devices recommended for individuals with profound sensorineural or mixed hearing loss. The implant consists of internal and external components that convert sound into electrical signals that bypass damaged hair cells in the cochlea by directly stimulating the auditory nerve (Figure 7).[29] A cochlear implant is implanted by an ear, nose and throat (ENT) specialist. It consists of an internal electrode array implanted into the cochlea and an external processor worn behind the ear. Following surgery, people with cochlear implants participate in auditory rehabilitation to learn how to interpret signals from the cochlear implant. Rehabilitation typically includes speech and language therapy and auditory training.[9]

Figure 8. Middle Ear Implant.
Middle Ear Implants

Middle ear implants are a good option for people who do not benefit from hearing aids or cochlear implants. Middle ear implants are surgically placed devices that directly stimulate the middle ear (Figure 8). The implant is attached to one of the small bones in the middle ear and works with an external sound processor. This allows sound to be transmitted directly to the inner ear, bypassing the ear canal.[30] Compared to traditional hearing aids, middle ear implants offer better sound, less feedback, and are more discreet.[9]

Troubleshooting Common Hearing Aid Issues

Here are some tips to troubleshoot common hearing amplification device issues when no audiologist is available.

There is no sound or the sound is distorted or weak:

  • check if the device is on and the microphone isn't muted (if using a phone)
  • ensure the hearing aid is correctly inserted, checking the ear mould or dome and tubing
  • check for damage to the hearing aid
  • for battery-powered hearing aids, check that the batteries are inserted correctly, and that they are clean and not expired
  • for rechargeable hearing aids, ensure the hearing aid is fully charged and has been correctly inserted into the charger
  • check for moisture or a broken receiver wire in the device
  • for receiver-in-the-canal hearing aids, check and replace the wax filter if blocked

There is a whistling or buzzing sound:

  • ensure the ear mould or dome is correctly inserted in the ear
  • check that the tubing is not loose, split, or kinked and that the hearing aid is not damaged

Batteries are draining quickly or the rechargeable batteries are not charging:

  • for disposable batteries, check and record the expiry dates on the packaging
  • for rechargeable devices >3 years old, consider a professional checkup
  • ensure rechargeable hearing aids are correctly inserted into the charging dock and that there is no dust or debris in the port
  • check that the charger is correctly plugged into the power outlet

There are Bluetooth® connectivity issues:

  • ensure Bluetooth is activated on the phone and that the devices are paired
  • check that the hearing aids are within range to connect
  • download and use the cell phone app for the hearing aid (if available)
  • clear the cache on the cell phone by switching it on and off

Conclusion

Hearing loss affects millions of individuals globally and can impact communication, mental health, cognitive function, and overall quality of life. Fortunately, various assessment methods and assistive technologies are available to support diagnosis and rehabilitation. Audiologists play a vital role in guiding individuals through appropriate amplification strategies, managing expectations, and addressing functional and psychosocial concerns. With increasing innovation and accessibility, hearing devices are more effective and user-friendly than ever—yet equity in access and long-term support remains a priority across global health settings.

Resources

References

  1. ↑ Henderson N, Hodgson S, Mulhern B, Page K, Sampson C. A qualitative systematic review of the impact of hearing on quality of life. Qual Life Res. 2025 Apr;34(4):879-892.
  2. ↑ 2.0 2.1 World Health Organization. Deafness and hearing loss [Internet]. 2025 [Accessed: 4 April 2025]. Available from: https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss
  3. ↑ 3.0 3.1 Schuster-Bruce J, Gosnell E. Conventional Hearing Aid Indications And Selection. [Updated 11 Dec 2020 24]. Available: https://www.ncbi.nlm.nih.gov/books/NBK567712/ ( accessed 4 April 2025)
  4. ↑ Campos JL, Launer S. From Healthy Hearing to Healthy Living: A Holistic Approach. Ear Hear. 2020 Nov/Dec;41 Suppl 1:99S-106S.
  5. ↑ Gilbert PUPA. The ear. In: Gilbert PUPA editor. Physics in the Arts (Third Edition). Academic Press, 2022. p321-30.
  6. ↑ Sheikh A, Bint-e-Zainab, Shabbir K, Imtiaz A. Structure and Physiology of Human Ear Involved in Hearing [Internet]. Auditory System - Function and Disorders. IntechOpen; 2022. Available from https://www.intechopen.com/chapters/82266 [last access 29.03.2025]
  7. ↑ Salmon MK, Brant J, Hohman MH, et al. Audiogram Interpretation. [Updated 2023 Mar 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK578179/
  8. ↑ 8.0 8.1 8.2 8.3 Alshuaib WB, Al-Kandari JM, Hasan SM. Classification of Hearing Loss [Internet]. Update On Hearing Loss. InTech; 2015. Available from https://www.intechopen.com/chapters/49574 [last access 29.03.2025]
  9. ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 9.11 9.12 9.13 9.14 9.15 9.16 9.17 Venter M. Assistive Technology for Hearing Course. Plus, 2025.
  10. ↑ Collins L. Understanding Mixed Hearing Loss.2023 Available from https://treblehealth.com/mixed-hearing-loss/ [last access 29.03.2025]
  11. ↑ National Research Council (US) Committee on Disability Determination for Individuals with Hearing Impairments; Dobie RA, Van Hemel S, editors. Hearing Loss: Determining Eligibility for Social Security Benefits. Washington (DC): National Academies Press (US); 2004. 6, Impact of Hearing Loss on Daily Life and the Workplace. Available from https://www.ncbi.nlm.nih.gov/books/NBK207836/ [last access 30.03.2025]
  12. ↑ Lin FR, Pike JR, Albert MS, Arnold M, Burgard S, Chisolm T, Couper D, Deal JA, Goman AM, Glynn NW, Gmelin T, Gravens-Mueller L, Hayden KM, Huang AR, Knopman D, Mitchell CM, Mosley T, Pankow JS, Reed NS, Sanchez V, Schrack JA, Windham BG, Coresh J; ACHIEVE Collaborative Research Group. Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE): a multicentre, randomised controlled trial. Lancet. 2023 Sep 2;402(10404):786-797.
  13. ↑ Sheng T, Pasquesi L, Gilligan J, Chen XJ, Swaminathan J. Subjective benefits from wearing self-fitting over-the-counter hearing aids in the real world. Front Neurosci. 2024 Apr 18;18:1373729.
  14. ↑ Brenowitz WD, Wallhagen MI. Does Hearing Impairment Affect Physical Function?: Current Evidence, Potential Mechanisms, and Future Research Directions for Healthy Aging. JAMA Netw Open. 2021 Jun 1;4(6):e2114782.
  15. ↑ Huang AR, Lin FR. Hearing loss and dementia in older adults: A narrative review. J Chin Med Assoc. 2024 Mar 1;87(3):252-258.
  16. ↑ Assi S, Twardzik E, Kucharska-Newton AM, Windham GB, Reed NS, Palta P, Martinez-Amezcua P. Hearing Loss, Hearing Aids, and Functional Status. JAMA Otolaryngol Head Neck Surg. 2024;150(8):705–712.
  17. ↑ Lew HL, Tanaka C, Pogoda TK, Hall JW. Auditory, Vestibular, and Visual Impairments. Editor(s) Cifu DX. In: Braddom's Physical Medicine and Rehabilitation (Sixth Edition), Elsevier 2021: 1101-1120.
  18. ↑ The Role of an Audiologist in Hearing Loss Treatment. 2024. Available form https://slenthearing.com/the-role-of-an-audiologist-in-hearing-loss-treatment/ [last access 30.03.2024]
  19. ↑ 19.0 19.1 19.2 19.3 Venter M. Assistive Technology for Hearing. Plus Course 2025
  20. ↑ UC Speech and Hearing. Adult hearing test - Audiology at the University of Canterbury. Available from: http://www.youtube.com/watch?9u9Ja4wyUaU [last accessed 30/3/2025]
  21. ↑ Livingston G, Huntley J, Sommerlad A, Ames D, Ballard C, Banerjee S, Brayne C, Burns A, Cohen-Mansfield J, Cooper C, Costafreda SG, Dias A, Fox N, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Ogunniyi A, Orgeta V, Ritchie K, Rockwood K, Sampson EL, Samus Q, Schneider LS, Selbæk G, Teri L, Mukadam N. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. 2020 Aug 8;396(10248):413-446.
  22. ↑ Powell DS, Oh ES, Reed NS, Lin FR, Deal JA. Hearing Loss and Cognition: What We Know and Where We Need to Go. Front Aging Neurosci. 2022 Feb 28;13:769405.
  23. ↑ 23.0 23.1 A landmark study of the effect of hearing intervention on brain health in older adults. Available from https://www.achievestudy.org/ [last access 30.03.2025]
  24. ↑ 24.0 24.1 Marcos-Alonso S, Almeida-Ayerve CN, Monopoli-Roca C, Coronel-Touma GS, Pacheco-López S, Peña-Navarro P, et al. Factors impacting the use or rejection of hearing aids-a systematic review and meta-analysis. J Clin Med. 2023 Jun 13;12(12):4030.
  25. ↑ Knoetze M, Manchaiah V, Mothemela B, Swanepoel W. Factors Influencing Hearing Help-Seeking and Hearing Aid Uptake in Adults: A Systematic Review of the Past Decade. Trends Hear. 2023 Jan-Dec;27:23312165231157255.
  26. ↑ Manchaiah V, Swanepoel W, Sharma A. Prioritizing research on over-the-counter (OTC) hearing aids for age-related hearing loss. Front Aging. 2023 Mar 23;4:1105879.
  27. ↑ Ellsperman SE, Nairn EM, Stucken EZ. Review of Bone Conduction Hearing Devices. Audiol Res. 2021 May 18;11(2):207-219.
  28. ↑ Zhang G, Chen R, Ghorbani H, Li W, Minasyan A, Huang Y, Lin S, Shao M. Artificial intelligence-enabled innovations in cochlear implant technology: Advancing auditory prosthetics for hearing restoration. Bioeng Transl Med. 2025 Jan 9;10(3):e10752.
  29. ↑ Sutton AE, Krogmann RJ, Al Khalili Y. Cochlear Implants. [Updated 2025 Jan 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from https://www.ncbi.nlm.nih.gov/books/NBK544280/ [last access 31.3.2025]
  30. ↑ Haynes DS, Young JA, Wanna GB, Glasscock ME 3rd. Middle ear implantable hearing devices: an overview. Trends Amplif. 2009 Sep;13(3):206-14.
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