A drive sprocket for an endless chain on a track-type undercarriage includes a toothed wheel having a plurality of circumferential teeth extending from a root circle. Herein, original musical tone data \u03c9 c1 are slightly modified in pitches to produce musical tone data \u03c9 c2 with respect to a prescribed tone color. A header of a second frame is scrambled based on a second unique word. The support region defining two members spaced apart sufficient to enable an edge of the panel to extend partially therebetween.