Help need for a micro audio receiver & speaker

Hi
Can anyone help, i have been asked to research into the posibility of making a very small audio reciever with a very small speaker attached which can pick up voice audio from a hand held transmitter and that can be heard from a few feet away from the inbuilt / attached speaker. Main consideration is size - as small as possible......speaker, receiver and battery can be seperated if required but needs to be concealed in a belt or similar.
Any ideas would be appreciated.
Best Rgds
Kev

Sounds like you've loosely described a hearing aid.