Taking inspiration from the iPhones strobe light text alert. What I’m thinking is some sort of clothing such as a light jacket, or a personal accessory such as a bracelet. A light would flash when you received a message, thus illuminated the garment or accessory. The catch behind this piece is that you can be alerted even when away from devices, and therefore not miss any important conversation.
Another idea I had was some sort of wearable synced to your music. The technical aspects would be similar to above in regards to illumination as an output. The main difference is that the output would serve as a display of what was playing in a sense. It would do this by either taking the different audio frequencies or by an app that sends OSC(open sound control) messages to the software controlling the lighting patterns.