The Vibeat range of devices allows people who are deaf or hard of hearing to enjoy music through vibration. It is a fashionable set that includes a bracelet, neckpiece, and pin. Working like headphones, the separate pieces combine to create a system that makes vibrations from music tracks. Each piece reacts to higher or lower ranges, enabling the wearer to feel the music through touch. They connect to any Bluetooth-enabled device that can serve as the music source. Within the Vibeat pieces are internal motors that cause them to vibrate at various rates.
https://www.dezeen.com/2016/08/07/liron-gino-design-vibeat-listening-devices-wearable-hearing-impaired-tactile-music/