Flat aluminum bars and aluminum electrical conduit will also sing if stroked with rosin. It requires practice. To avoid sticky rosin-fingers, you can impregnate a piece of leather or scrap of heavy fabric with powdered rosin. Sound travels through air about 340 meters per second or 750 miles per hour. The temperature, pressure and density of the air alters the speed of sound.
Sound travels faster in liquids than it does in gases.
It travels even faster through solids. What we normally call sound is produced when objects vibrate in air. The vibrating object causes the surrounding air to vibrate. Our ears detect the waves of vibrating air molecules. Sound must have a medium though which to travel.