This particular icon is made up of half circles. There are two half circles positioned next to each other with their flat sides facing each other. A long curved line connects them both.
This Headphones icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 5,500 icons, all in the same style and quality.