Netherlands-based Studio Toer designed the Bongue amplifier which is powered by kinetic energy when you moving it’s arm.
Bongue is a physic amplifier of mobile audio. The dynamic qualities give it a multi-censorial experience for daily life. When Bongue is fixed it’s only amplifying the sounds from the music-device itself. When you start moving the arm it will give energy to the amplifier and by that it will increase the volume of the musicplayer.