The styrophone is a modern musical instrument made from a Styrofoam (expanded polystyrene foam) box that is forced to vibrate by friction against a wooden stick. Technically, the instrument is a type of friction idiophone. Styrophones tend to last for only one performance, as the friction destroys the material.

The name styrophone has also been used to describe a cheap home-made loudspeaker whose cone is made from a Styrofoam cup.