Celia Sheen plays the theme tune from ITV's drama series "Midsomer Murders" on the Theremin. She has done so, along with incidental music, on the soundtrack of every episode for fourteen years. This fascinating instrument was the world's very first electronic instrument, invented in 1920 by Russian scientist Lev Theremin. Of course, nobody ever sees Celia's performances on the recordings, but what makes it interesting is that the Theremin is played without being touched!

It's one of the most recognizable sounds in pop music. It also turns out to be one of the most misunderstood. That high-pitched sound in The Beach Boys' 1966 masterpiece "Good Vibrations" is always assumed to be a theremin. But it's not. And this week, Paul Tanner — the man who invented the instrument that actually made that unforgettable sound — has died.

First, some background: The theremin is an instrument invented by Leon Theremin in 1928. It has two metal antennae, and you play it not by touching it, but by moving your hands in the air between the antennae to control the pitch and volume of the sound. It takes a lot of practice to play the theremin, so in the 1950s, trombonist Paul Tanner and an amateur inventor named Bob Whitsell made an instrument that made sounds similar to Leon Theremin's creation, but made it a lot simpler for non-experts to hit specific notes and control the volume.