Here are the visual representations of 12 piano notes as imaged using a cymascope. Sound is nothing but a vibration of a particular frequency and amplitude until it reaches a physical medium and can be transformed into tangible sensation. That can happen at our eardrum, providing us with the mechanical stimulus underlying hearing, or via machine.
By using special equipment to view vibrations on a latex membrane or surface of water, these folks can morph the unseeable into the seeable. Check out their website below for some great imagery, but be warned that a few of their supposed “applications” for the technology sound a little mystical to me.