cylinder (much like a barrel) that is also rounded out by a lathe. Solid shells are constructed of one solid piece of hollowed wood. The heads or skins used are a batter head (the playing surface on the top of the drum) and a resonant (bottom) head. The resonant head is usually much thinner than the batter head and is not beaten while playing. Rather than calfskin, most modern drums use plastic (Mylar) skins of around 10 mils thickness, sometimes with multiple plies (usually two) of around 7 mils for the batter head. In addition, tone control rings or dots can be applied, either on the outer or inner surface of the head, to control overtones and ringing, and can be found positioned in the centre or close to the edge hoops or both. Resonant heads are usually only a few mils thick, to enable them to respond to the movement of the batter head as it is played. Pipe band requirements have led to the development of a Kevlar-based head, enabling very high tuning, thus producing a very high-pitched cracking snare sound. A new technique used to improve the sound quality during snare drum construction is symmetrical venting. In contrast to a standard single vent hole, air can easily travel through and around the instrument without getting caught. This rapid movement creates a smoother, stronger sound. History The snare drum seems to have descended from a medieval drum called the tabor, which was a drum with a single-gut snare strung across the bottom. It is a little bigger than a medium tom and was first used in war, often played with a fife (pipe); the player would play both the fife and drum (see also Pipe and tabor). Tabors were not always double-headed and not all may have had snares. By the 15th century, the size of the snare drum had increased and had a cylindrical shape. This simple drum with a simple snare became popular with the Swiss mercenary troops who used the fife and drum from the 15th to 16th centuries. The drum was made deeper and carried along the side of the body. Further developments appeared in the 17th century, with the use of screws to hold down the snares, giving a brighter sound than the rattle of a loose snare. During the 18th century, the snare drum underwent changes which improved its characteristic sound. Metal