Material also needs to be designed so that it can be quickly and cheaply reformatted into languages other than English. Dr. McPherson stressed that any prospective device needed to be low cost, as should any replacement parts. The cost of batteries coupled with the low income of many people makes it imperative that batteries be as energy efficient as possible. Any device also needed to be extremely robust and able to withstand dust and high humidity. He pointed out that the Liverpool Field Audiometer used weapons-grade plastic.
Care needs to be taken to ensure the device is comfortable to wear in hot and humid climates.
Switches need to be kept to a minimum. A central repair depot would be wonderful. Peter Blackwell was then asked to give an overview of his experiences in China since 1983. It is estimated that there are 1.7 million deaf children in China, but that the use of hearing aids and other devices is not widespread. Most hearing aids come in from Hong Kong and are still relatively expensive.