• • Hearing impairment - moderate
• • • Hearing impairment - severe
Conventional noise-excluding techniques are probably inappropriate in ordinary consumer terminals, but it is still possible to limit the adverse effects of ambient noise through careful handset design.
In particular it is important that the earpiece is large enough and shaped to cover most of the ear. This will help seal the ear to reduce external noise interference for persons with reduced hearing.
A small or badly shaped earpiece will not seal well against external noise.
