Nic Wallenberg's The Human Speaker is a curious electrical collar that allows you to vocalize electronic sounds without using your voicebox.
Usually when singing or speaking, vibrations originating in the voice box are transported up the throat to the mouth, before emanating from the lips as sound waves.
The Human Speaker works much the same way, except the collar, rather than voice box, is the source of the vibrations. The pitch of the notes that emerge is determined by the collar, which, Wallenberg writes, can produce up to two notes at a time. Wearers can manipulate the sound with their mouths much as they would normally.
Wallenberg points out that the two-note limit can be cheated if you have multiple collars, or access to a camera and some video-editing software, apparently, judging from the below.