A piano is an instrument. So is a violin. But what about the voice? Or a fork? Or a mobile phone? So what is (really) a musical instrument? That was the title of a short lecture I held at UiO’s Open Day today. The 15-minute lecture is a very quick version of some of the concepts I have been working on for a new book project. Here I present a model for understanding what a musical instrument is and how new technology changes how we make and experience music.