A pretty niche application for these kind of shaker systems is monitoring for live musicians. As of now there are products for drummers and bass players that he

A pretty niche application for these kind of shaker systems is monitoring for live musicians. As of now there are products for drummers and bass players that help them experience the bass response when they use in-ear minitoring systems, e.g. vibrating floor boards for bass players and shaking drum stools for drummers. Having this more mobile would certainly help.