4.9.1. Otoscopes

Traditional otoscopes are used for ear examinations and cost U.S.$100 to U.S.$4,000. Low cost otoscopes have been developed for use in L.M.I.C.s includig the Arclight costing around U.S.$10-15 and mobile-based otoscopes such as CellScope and Medtronic's Ear Screening Kit (see Case Study 8). While these otoscopes do not have the same levels of magnification, have some functional limitations, and have had limited clinical validation to date,72 they are often preferred by N.G.O.s since they are lightweight, affordable and easy to use.

4.9.2. Audiometers

Pure-tone audiometry is the gold standard to identify people with hearing loss, but most audiometers that are currently in use are complex, require extensive training and experience that only audiologists have, and require a sound-proofed environment. Mobile audiometers such as those by SHOEBOX, HearX and KUDUWave address some of these critical challenges (Table 6). HearX and SHOEBOX are tablet-based audiometers, with specialised software and headphones. KUDUWave is a headset that is able to perform automated audiometry. These devices are clinically validated and have also undergone some field-testing.

TABLE 6: MOBILE AUDIOMETERS

PRODUCT NAME	SHOEBOX AUDIOMETRY73	KUDUWave	HearTest
Manufacturer	SHOEBOX Ltd. (Canada)	eMoyo (South Africa)	HearX Group (South Africa)
Description	iPad-enabled software screening and diagnostic software	Portable and boothless screening and diagnostic audiometer	Portable, Android mobile-enabled screening and diagnostic software
Audiogram Output	Yes	Yes	Yes
Included in upfront bundled costs	iPad with Software, calibrated Radioear headphones, cloud-based data management, warranty, annual calibration	Sound-booth equivalent noise blocking headset audiometer, consumable pieces, software, internal microphones, ear tips, 3-year warranty, digital calibration	Samsung phone with software, calibrated audiometric headphones, cloud-based data management, subscription-based software, 2-year warranty, annual calibration
Upgrade options	Bone oscillation, customized managed service, custom integration	Bone oscillation (Plus + Pro); Built-in tympanometer (Pro T.M.P.)	Extended high-frequency audiometry, Advanced attenuation option, video-otoscope (hearScope) integration
Personnel Requirements	Standard – Minimal Training Pro – Audiologists / E.N.T. surgeon only	Minimal Training Required	Minimal Training Required
Power	iPad charger	Requires connection to a PC/Laptop	Battery or phone charge, offline & online
Tele-audiology enabled	Yes	Yes	No

Product photos used with company permission.

Some of the advantages of these devices include:

• LOWER SKILL REQUIREMENTS. Automated audiometry capabilities allow lower-skilled workers to provide diagnostic services in uncomplicated cases. The training to effectively operate these devices can be between 1-3 days for nurses, primary healthcare workers or community health workers.
• POTENTIAL FOR SELF-CALIBRATION. Although annual calibration is not clinically required with the current generation of equipment, this has been set as an industry requirement and is often mandated by the government. These calibrations are usually performed by local distributors, but if none is available locally, audiologists are required to incur shipping costs to send the product to their closest distributor for re-calibration. Calibration can, therefore, be a costly service and disruptive to service delivery. However, SHOEBOX re-calibration services are included in the annual subscription fee. HearX is currently setting up remote calibration facilities for its devices and also offer swap-out options to ensure minimal downtime for customers. KUDUwave includes digital calibration verification where the device completes its own calibration electro-acoustically and the manufacturer eMoyo only requires regular calibration every three years.
• LOWER INFRASTRUCTURE REQUIREMENTS. Current screening and diagnostic protocols also require the use of a sound booth among other related infrastructure requirements. Not only are these sound booths expensive and difficult to build, but they are not portable. This limits the ability to conduct outreach services. Mobile audiometers, because they use noise-cancelling headphones and algorithms that address noise interference in the environment, can be used in a quiet setting.
• LOWER COSTS. Lower device costs, lower skill and training requirements, and reduced time per screening support overall reduced costs per screening.

Many of these companies are already working with governments. For example, KUDUWave works with the government of South Africa for their school screening program and has been used by healthcare workers for hearing screening within other public health programs. Uptake of these devices is limited by lack of field evidence to support use at scale and across a variety of different contexts.

4.9.3. Tele-audiology

The advent of new technology has also enabled the use of tele-audiology (refer to Case Study 9). This allows audiologists to diagnose, fit and provide rehabilitation services to people remotely, allowing for increased reach of services and stronger referral networks, as well as training and mentorship for hearing aid technicians. Recent reviews of tele-audiology have noted that there is an increasing role for tele-audiology and that it is feasible and likely effective, but may be limited by a lack of evidence protocols and models of service delivery, perceptions of tele-audiology by end users and clinicians, and resource constraints.74

4.9.4. Earmould innovations

Novel methods have allowed earmoulds to be developed on the spot within two hours and this can have an impact on hearing aid fitting and usage.

• MOBILE EARMOULD LAB: EARS Inc. set up a mobile earmould lab using proprietary earmould equipment that allows them to produce hundreds of earmoulds in a day using local material, reducing the wait times that could be upwards of one year from a centralised earmould lab to same day. This enabled children to wear hearing aids from the day that they were prescribed and therefore increased hearing aid uptake.77
• 3D PRINTING OF EARMOULDS: 3D printing techniques can be incorporated to create custom earmoulds. For most 3.D. printing technology, an ear impression must still be taken using silicone or methyl methacrylate. The impression is then scanned into a 3D design computer program, where the 3D image is refined and sent to a 3D printer for printing. The material used for printing varies based on the type of printer. Digital ear scanning technologies that use lasers and membranes to scan the inside of the ear have recently come to market, such as the Lantos Technologies 3D scanner or the Otometrics Otoscan. As the price of 3D scanners and printers comes down, 3D printing of ear moulds may become a viable option to produce a higher number of earmoulds at the point of care than through traditional methods.

4.9.5. Rechargeable Batteries

While some experts and innovators have advocated and investigated the use of rechargeable batteries, including solar, in certain instances, innovation in this space has been limited but is expected to grow. Currently, the incremental benefits of rechargeable batteries do not outweigh the costs as users may buy two sets of rechargeable batteries so that they can use one while recharging the other. Use of internal batteries that can be charged via U.S.B. has also been investigated, similar to how many other electronic devices are charged. The product may not be used when charging. There are concerns that the uneven electrical discharge from some rechargeable hearing aids can damage the signal processors in hearing aids and can result in sub-optimal sound quality. Companies, such as Solar Ear, have developed a solar charging dock on which the entire hearing aid can be placed.