http://informahealthcare.com/idt ISSN 1748-3107 print/ISSN 1748-3115 online Disabil Rehabil Assist Technol, Early Online: 1–5 ! 2014 Informa UK Ltd. DOI: 10.3109/17483107.2014.907365

REVIEW PAPER

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Hearing assistive technologies in developing countries: background, achievements and challenges Bradley McPherson Division of Speech and Hearing Sciences, Faculty of Education, The University of Hong Kong, Hong Kong, China

Abstract

Keywords

Purpose: The burden of hearing impairment and disability is substantial in the developing world. This review outlines the associated need for amplification devices in low and medium income countries and some of the initiatives that have been taken to improve access to such devices, particularly hearing aids. The main observed barriers to access are listed and possible ways to improve access are considered. Methods: Prevalence estimates for disabling hearing impairment are reviewed and a number of national and international examples of initiatives to facilitate use of hearing assistive devices in low and medium income countries are provided. Technologies that are potentially appropriate for hearing instruments in developing countries are suggested, as well as fitting programs that are more likely to be maintained over the long term. Results: Challenges to successful hearing instrument fitting in low and medium income countries are many. However, some programs point the way to improved access to such devices. Successful hearing aid fitting programs in developing countries have typically combined appropriate technology with a sustainable local support base. Conclusions: With a rising middle class in many developing countries, advances in technology, and ongoing training programs for those involved in amplification fitting, hearing device usage rates may eventually reach parity with those in developed economies.

Appropriate technology, audiology, developing countries, hearing aids, hearing disorders, training History Received 5 March 2014 Accepted 18 March 2014 Published online 7 April 2014

ä Implications for Rehabilitation  



The historical development of affordable hearing device fitting provision in low and middle income countries is outlined. Three key barriers to widespread access to hearing device provision in many low and middle income countries (LMICs) are identified: lack of trained personnel, the high cost of many existing devices marketed in LMICs and limited public awareness of the benefits of hearing assistive technologies. Examples of programs that have sought to overcome these barriers in LMICs are given and may influence the ways in which future hearing health care is provided.

Background The rehabilitation of individuals with hearing loss is a multistage process. The identification of those with likely hearing loss is followed by diagnostic assessment of ear and hearing health, counselling, and very often the provision of hearing assistive technologies – typically hearing aids. The ensuing stages of ear impression taking, ear mould manufacture, hearing device fitting and post-fitting follow-up, with further counselling and device adjustment, completes the process. For many years, most

Address for correspondence: Professor Bradley McPherson, Division of Speech and Hearing Sciences, Faculty of Education, University of Hong Kong, Pokfulam Road, Hong Kong, China. Tel: +852 3917 1592. Fax: +852 2559 0060. E-mail: [email protected]

individuals in developed economies have been able to access hearing health care through private and publically funded aural rehabilitation systems. However, this is not the case in many low and medium income countries (LMICs), where the prevalence of child and adult hearing impairment is substantially higher [1]. World Health Organization [2] figures suggest that in LMICs 20% of those with hearing loss are in need of hearing aids, and hence there are 72 million potential hearing aid users. However, it is estimated that 53% of those in LMICs who could benefit to hearing assistive technology have access to any device [3]. Assistive hearing technology can be defined as any device or software that enables individuals with hearing loss to better function within their personal environment. Common examples of assistive hearing technology include hearing aids and also assistive listening devices – devices other than hearing aids, such as telephone amplifiers, visual alerting systems and earphone/ smartphone amplification applications [4]. The need for enhanced access to hearing devices in low and medium income countries has been known for many years. In the

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1960s, the first international discussions on hearing aid provision in developing countries – particularly Africa – were initiated by organizations such as the Commonwealth Society for the Deaf (now Sound Seekers), based in the UK [5]. These events led to a series of small scale projects throughout the developing world that sought to improve access to hearing health care and aural rehabilitation, particularly for children [6,7]. Often projects involved prevalence research, combined with technical assistance to establish hearing health care clinics through training programs and equipment grants. These projects were important both locally and in a wider, global sense. They motivated many industrialized economy professionals (typically audiologists, otolaryngologists and special educators) to engage with LMIC groups working for the advancement of persons with hearing loss. This led throughout the 1990s and into the 21st century in the growth in humanitarian activities such as medical missions [8], training programs [9] and commitments to provide affordable hearing assistive devices [10] in LMICs. Some of these activities are supported by charitable foundations, at times linked to hearing device manufacturers [11] and others are linked to faith-based organizations [12,13]. The consequent critical mass of professionals in developed societies with an awareness of LMIC needs led to the establishment of humanitarian interest groups and/or humanitarian awards in many professional societies (such as the International Society of Audiology, American Academy of Audiology, American Academy of Otolaryngology – Head and Neck Surgery). Some groups, such as Audiology Australia and the Hong Kong Society of Audiology, now directly encourage members to participate in humanitarian activities by granting continuing professional development points – essential for maintaining membership – for this activity. A consortium of professional groups, acknowledging the importance of an international profile for hearing health issues, particularly those related to LMICs, now funds the key management position within the Prevention of Blindness and Deafness Programme of the World Health Organization (WHO). Since 1985 WHO has taken a sustained interest in the prevention of hearing loss [14]. WHO has organized forums and workshops that have linked professionals in LMICs with those in industrialized countries and collected detailed data on the burden of hearing loss in LMICs, with a long-term commitment to providing technical assistance for national programs for the prevention of deafness and hearing loss [15,16]. Prevention may primary, the direct prevention of hearing disorders, or secondary, the limitation of long-term hearing disability arising from a disorder. The WHO interest in hearing assistive devices arises from recognition that although some forms of hearing loss are due to preventable disorders, such as middle ear infections and noiseinduced hearing loss, there are vast numbers of individuals with hearing loss that cannot be prevented. In these latter cases, hearing assistive technologies are essential secondary prevention tools. Over time, awareness grew of both the magnitude of the need and the complexities involved in service delivery, as noted in a 1991 European Union symposium [17] and the WHO Guidelines for the Provision of Hearing Aids and Services for Developing Countries [18]. The multistage nature of hearing device fitting meant that LMIC service provision paradigms developed for other disorders, such as vision and mobility impairments, were not appropriate. Specific hearing health care service provision strategies are often unsuccessful due to a number of main barriers. First, a relatively high level of training is required for health care workers to provide a quality aural rehabilitation service. Trainers with the requisite skills are typically not available [19]. Secondly, hearing devices are usually expensive in a LMIC context [20–22] and, thirdly, there is limited public awareness and

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acceptance of hearing devices as a way to ameliorate hearing disability [23–25].

Achievements Successful hearing health care programs in LMICs typically acknowledge all three main barriers when commencing their work and devise methods to reduce the constraints imposed by these barriers. Successful programs are those that use an evidencebased fitting protocol to provide affordable assistive hearing devices in a sustainable manner to individuals with hearing loss. An example is the ongoing program undertaken by Better Hearing Philippines which has over a 5-year period trained 43000 rural health workers in basic hearing health care, initiated pilot affordable hearing aid fitting in underprivileged communities, and developed a publicity campaign aimed at raising awareness of hearing disability and ways to reduce it [26]. Training both community health and education sector workers was carried out in Ghana, with attention paid to the special education coordinators who work at district level throughout the country and who are influential in shaping attitudes within school communities. In Ghana, hearing aids have been provided free-of-charge by charitable organizations or at relatively low cost through government bulk purchase [21]. Several pilot programs in disadvantaged regions of China have focused on affordable hearing assistive device fitting for children [27]. One project sought to raise awareness of hearing disorder through mass screening campaigns in parallel with hearing health care training of selected primary school teachers. The teachers were then involved in assessment activities and device fitting for children in need of amplification. This project was unusual in that it established the costeffectiveness of the rural, teacher-based project compared to conventional, audiologist-led projects in other regions. Mobile ear care services, e.g. in Nigeria [24] and Ghana [21] are another means that has successfully been used to raise awareness, provide training and distribute affordable devices – often in extremely underserviced rural areas. It should be noted that successful usage of assistive hearing devices in LMICs may have profound positive effects at many levels, including economic [28], social and educational [29]. Programs that are successful recognize the need to break down awareness and acceptance barriers and to fully involve the end user in the service provision process [30]. Programs also need to have a sustainable local support base, and an assured supply of appropriate assistive hearing devices is critical. A priority is that instruments need to be affordable, either directly affordable to the user or affordable to organizations that purchase them on behalf of the individual with hearing loss. Several hearing aid purchase consortiums have been organized that enable members to buy devices in bulk [20,21,31], at very considerable savings for the charitable organizations involved. Typically these consortiums link with the main multinational device manufacturers and purchase reliable, well known device models that are coming to the end of their sales cycle in developed economies and hence can be heavily discounted by manufacturers. Even so, prices may not be affordable, particularly in least developed countries, and access to hearing devices still may be very limited. An alternative strategy is to purchase devices from smaller, national or social enterprise manufacturers. Both India and China have hearing device manufacturers with products at very much lower price points. Within India national manufacturers have established a large market share and this has helped in the growth of rehabilitation services for individuals with hearing loss. However, both in India [32] and in China [33] some locally produced hearing assistive devices have a reputation for design and quality control issues and maintenance costs need to be carefully

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DOI: 10.3109/17483107.2014.907365

considered when making bulk purchases. Social enterprise purchase solutions are also available, with the most prominent provider being Solar Ear (www.solarear.com.br). Solar Ear operates a hearing device assembly plant in Brazil, and engages workers with hearing loss for the assembly process. Behindthe-ear hearing aids are produced that meet a wide range of hearing loss configurations and the devices are compatible with a solar-powered battery recharging station also manufactured by Solar Ear. The hearing devices are intended for use in LMICs and to be affordable in many locations. However, once again quality control issues need to be considered [34] and related maintenance costs planned for. The high and ongoing expense of hearing device batteries led to the development of the Solar Ear battery charger [35] and this is a worthwhile attempt to reduce these costs. Another low cost solar charging station has been developed by Impact UK (www.impact.org.uk) for use in conjunction with hearing assistive devices in LMICs. Several research groups with a social enterprise philosophy have used the WHO Guidelines for the Provision of Hearing Aids and Services for Developing Countries [18] as a starting point for the design of assistive hearing devices. A Brazilian team has developed a prototype digital behind-the-ear hearing aid assembled from off-the-shelf components that meets both Brazilian government [36] and WHO guidelines [37]. The hearing aid was deemed to be low cost if mass produced. Similarly, a group of researchers based in Thailand has used WHO guidelines to inform their own digital hearing aid prototype. In this case, a digital body level hearing aid was produced [38]. In both cases, simple to use software to program, the instruments were developed along with the device itself. The Thai team has also created a low cost FM assistive listening system for use in classrooms by children with hearing loss [39,40], again using off-the-shelf electronic components. Further development of these and other initiatives [41] will reduce the barriers to assistive hearing device access by reducing costs, simplifying fitting procedures and introducing devices to a wider section of the population with hearing impairment. Simplifying fitting procedures, in particular, assists in the training process at sub-professional level. Professional training programs are now well established in many LMICs, including Brazil, China, Columbia, India, the Philippines, South Africa and Thailand. However, there is still a great shortage of audiologists in most LMICs [19]. The demand for assistive hearing devices could be better met in LMICs if professional involvement is supplemented with that of more generalist health workers. Several strategies have been suggested and successfully piloted, such as working in tandem with existing primary eye care workers [42] or integrating ear and hearing care into community-based rehabilitation programs [43]. Reducing the expenses associated with device fitting also involves consideration of the linkage of the device to the ear. If custom earmoulds are used costs can be high unless local workers are trained to undertake earmould manufacture and locally sourced materials are used. EARS Inc., an Australian non-profit organization, has implemented practical strategies for establishing low-cost earmould laboratories in LMICs [44]. Alternatively, non-custom ear fitting can be considered if appropriate for individual clients.

Challenges Barriers in LMICs to assistive hearing device access and auditory rehabilitation in general remain substantially unchanged since reports first detailed these in the 1980s [7,45]. Affordability has been discussed above – assistive technology is now available in many LMICs. However, it can be argued that in most cases it is

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still not truly ‘‘affordable’’ for the majority of those in need of support [20]. There are no robust assistive devices that meet WHO Guidelines for the Provision of Hearing Aids and Services for Developing Countries [18], and that can be purchased in LMICs inclusive of earmould and batteries for under USD50. Yet this would still be regarded as a substantial sum to pay for a device by many families in LMICs. Training programs appropriate to the needs of LMICs are still scarce and this is another major challenge yet to be overcome. The WHO has produced educational resources for primary and secondary level hearing health workers and these are a base for further curriculum developments [46]. Given the current shortage of hearing health care professionals in LMICs [19] many affordable device fitting programs have considered ways to minimize direct audiologist input, e.g. through the use of special education teachers [24,27] and nurses [26]. The recent popularization of online learning, combined with the nowadays high penetration of telecommunications services in LMICs, holds promise for the development of internet-based hearing health learning modules. Better trained primary and secondary hearing health workers – and their clients – may in future benefit from post-training telehealth support. Telehealth allows professionals to gain remote access to clients and local health workers and provide more sophisticated rehabilitation services than are locally available [47,48]. This may break the current tendency to dichotomise hearing device fitting programs as either ‘‘audiologist-led’’ or ‘‘community-based’’. A model ‘‘general audiology’’ curriculum has been designed by the International Society of Audiology [49] and offers guidance on what to include in an educational program at the full professional level. Existing university programs in developed economies typically do not focus on skills important in LMICs, and online learning for non-LMIC professionals who intend to work in LMICs would be valuable. Modules could include material that usefully extends the usual audiological scope of practice – e.g. by developing simple otological nursing skills [50] – although this has ethical and workplace implications that require careful consideration. Content providers based in LMICs, such as the well-established tertiary institutions in India [51] and South Africa [52] that teach audiology, would be well placed to create this type of educational material. Assistive hearing device technologies continue to grow more complex and many of the new innovations in this field may be useful in a LMIC context. These advances have been reviewed in detail elsewhere [53] and include improved wide range dynamic compression and noise reduction algorithms, digital speech enhancement, directional microphones, advances in acoustic feedback reduction, moisture and dust resistant casings, and self-adjustable or trainable hearing instruments. However, as noted above, for work in many LMIC environments simplicity of device fitting is essential. Basic open source hearing device prescription software that could be readily modified to suit particular fitter and client needs would be helpful in many situations, both for training and fitting purposes. However, at present, no such open source fitting software is available. As discussed above, a number of hearing health care programs have sought to change attitudes regarding hearing impairment and create an awareness of the ways that hearing disability can be mitigated. The World Health Organization and other international bodies have played a leadership role through their promotion of hearing health care in LMICs [42,43]. Some national and local agencies make very effective use of print, radio and other media to foster awareness, such as through China’s annual national ear care day [54]. Attitudes towards disability may only shift over time and with sustained input at the societal and individual levels [55]. More focus is needed on ways to improve overall knowledge

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of hearing health and the ways assistive devices can benefit those with hearing loss, their families and their societies. Anecdotal accounts [20,23,25] consistently note that awareness of these issues is still low in many LMICs. Despite an increasing interest in hearing assistive technologies in LMICs over the past decade there is a surprisingly small evidence-base to inform work in this field. Areas that require research are many. In particular, cost-benefit analysis of assistive device provision is important to justify current and future programs. This has been carried out in rural China [27] and India [56], but much more work with an economic focus is needed to justify chosen approaches to device provision. Research findings on the outcomes of assistive device fitting are also scarce [21]. Yet such research can provide cogent reasons why assistive devices are important in a LMIC context. A striking example – at a very fundamental level – is the finding that assistive technology wearing individuals with hearing impairment in Bangladesh reported a greater enjoyment of human rights than individuals with hearing impairment who did not wear hearing instruments [57]. Outcomes of assistive device fittings in developing countries are, again anecdotally, often very positive in terms of educational and vocational advancement but there is little valid scientific support for such claims. More outcome studies, particularly longitudinal research investigations, would provide policy makers and hearing health care workers with a better evidence base for future actions.

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Conclusions Long term demand for hearing health care can only increase in LMICs as most future world population growth will occur in the developing regions of Africa, Asia and Latin America [58]. The three main barriers – scarcity of trained hearing health care workers, lack of assistive devices that are affordable in a LMIC context and the limited public awareness and acceptance of hearing devices – are all surmountable given time and appropriate resources. Overcoming these barriers will be assisted by the rising middle class in many LMICs, which brings with it increased expectations and demand for health services [59]. The current increased level of interest in assistive hearing device technology for LMICs is symptomatic of a growing general awareness of the needs of those individuals with hearing impairment who live in LMICs. Over the next decade further breakthroughs in the provision of assistive hearing device technologies to many of those in need can be expected in LMICs. The long-term aim of all programs should be for assistive device market penetration to reach parity with that in developed economies.

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Acknowledgements

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The author thanks Katherine D. Seelman and Jackie L. Clark for their kind encouragement during the writing and review process for this article.

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Declaration of interest The author reports no declarations of interest. 24.

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Hearing assistive technologies in developing countries: background, achievements and challenges.

The burden of hearing impairment and disability is substantial in the developing world. This review outlines the associated need for amplification dev...
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