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| Technology related WHO’s criteria on hearing aids | |
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| (i) BTE is preferred, but body worn type may also be needed for low cost, ease of use, and availability of batteries, also in cases of rural areas where body worn is preferred | |
| (ii) Allowing ease of service, components available for five years; manufacturer provides sufficient detail | |
| (iii) HA should be powered by zinc air or secondary rechargeable cells; rechargeable types are preferred | |
| (iv) Operating in temperature 5–45 degree range, humidity 0–80% | |
| (v) Having means to reduce gain below 750 Hz | |
| (vi) Allowing at least 12 dB reduction at 250 Hz relative to 750 Hz | |
| (vii) Gain can be preset or adjusted by user | |
| (viii) At least 30 dB volume range, volume control clearly numbered | |
| (ix) Induction coil is an option but preferred | |
| (x) HA with AGC is preferred | |
| (xi) Manufacturer has ISO 9001 on quality management system | |
| (xii) HA should be designed such that risk of injury or discomfort to user is minimized | |
| (xiii) Manufacture should provide HA with at least few basic colors | |
| (xiv) The number of moving parts should be minimal | |
| (xv) DAI, FM, or other direct coupling input could be considered for educational settings but should not be considered priority if it jeopardizes the provision of hearing aids themselves | |
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