The device -- named "e-Mimi-kun" (good ear boy) -- doubles as an earphone and a microphone by detecting air vibrations inside the ear, developer NS-ELEX Co. said.

The ear-piece and an accompanying device can be connected to a mobile phone, or wirelessly to a Bluetooth handset, so that users no longer have to cover their mouths when speaking in a loud environment, the company said.

Exterior noise is reduced six-fold by the ear-piece, it said, while a chip developed by Sanyo Electric for the accompanying device reduces sound levels 10-fold, it added.

NS-ELEX believes the product would be useful for people working in places such as factories, restaurants, and amusement parks.