Bone conduction apparatus having tens therapy function

A bone conduction apparatus comprising:

• a receiver configured to receive audio data compressed in a predetermined manner by using wireless communication;
• a digital-to-analog converter configured to convert the audio data to an analog audio signal, and configured to output the analog audio signal;
• a plurality of housings comprising a first housing configured to be contacted with a user body and a second housing configured to be contacted with the user body;
• a plurality of bone conduction units comprising a first bone conduction unit provided in the first housing and a second bone conduction unit provided in the second housing, wherein the plurality of bone conduction unit is configured to convert the analog audio signal to a bone conduction signal and output the bone conduction signal;
• a plurality of metal electrodes comprising a first metal electrode placed at an outside of the first housing and a second metal electrode placed at an outside of the second housing;
• a frequency generator configured to generate a transcutaneous electrical nerve stimulation (TENS) signal;
• and
• a TENS signal amplification unit connected with the frequency generator and the plurality of metal electrodes, and configured to amplify the TENS signal and apply the amplified TENS signal to the plurality of metal electrodes.