sentences:  Roger Penney, the originator of rock autoharp, redesigned the autoharp's chord bar structure and gave the design to The Oscar Schmidt Company, the largest American crafter of autoharps.Since then, all major autoharp manufacturers worldwide have switched to making autoharps using Roger's design.He used contact mics and magnetic pickups to create a true 'electric autoharp', and invented a braille-type system of round and rectangular chord bar buttons (which allowed the player to know by touch exactly what chord they were playing without visual observance).