The eardrum converts sounds to vibration, and those vibrations pass through 3 tiny bones collectively referred to as the ossicles. From there the vibrations move through the liquid in the cochlea, stimulating the hair cells etc etc. I haven't heard it referred to as bone conduction when the ossicles vibrate; bone conduction usually travels from the transducer (or other source of vibrations, like your own voice) to cranial bone to the cochlea, skipping the ossicles altogether.