Various aspects include audio devices with a capacitive sensing interface along a compound curved wall. Some aspects of the disclosure relate to wearable audio devices with a capacitive sensing interface and a flexible printed circuit board (PCB) for detecting a touch command at the interface. In certain cases, the flexible PCB has at least one slit for conforming to the compound curve of the wall. In additional implementations, the inner surface of the wall is faceted and the flexible PCB conforms to the facets in the wall.