A bone conduction device, comprising: a sound input element configured to receive an acoustic sound signal; an electronics module configured generate an electrical signal representing said acoustic sound signal; and a transducer configured to generate motion of a mass component based on said electrical signal so as to generate one or more mechanical forces resulting in one or more of motion and vibration of a recipient's skull thereby causing sound perception, wherein one or more of the size and shape of said mass component is selectable at least partially based on a desired mechanical force to be generated by said transducer.