Drums are the world’s oldest musical instruments. Most of the drums from around the world bear a striking similarity to one another — most drums have a round shape. Their basic design has remained virtually unchanged for years as well. But why is it so? Why are drums round?
All drums produce sound when their membranes vibrate. The shape of the membrane determines how the sound waves generated behave. Drums are round because a round shell allows the sound waves produced to bounce around inside the drum evenly, causing the sound produced to be clearer and more distinct.
Are All Drums Round?
No, not all drums are round. Most drums are made in a round shape. However, there are drums that come in other shapes, such as square and octagon frame shapes. The Cajon, Gome and Pandero Jarocho are examples of such drums.
Square and octagon frame shape drums are usually made from tough animal hide. These drums are made using a resourceful tensioning system to give the drums a natural form. Non-round drums, particularly square frame drums, are dominant in countries such as Spain, Morocco, Peru, Ghana and Portugal.
A Cajon is a box-shaped drum that originates from the country of Peru. This drum is square-shaped and covered with a thin wooden membrane.
The Cajon is noted for its lightweight. The size and weight of a Cajon make it a wonderful instrument to travel and spontaneously perform with.
This instrument is relatively 18 inches tall and 12 inches wide. It is made of hardwood, and an extra layer of plywood nailed to the drum’s designated front part. This front part, which also serves as the striking surface of the Cajon drum, is commonly referred to as the tapa.
A circular hole is cut out of one of the sides of the Cajon. This is where the sound escapes. This cut outside is always behind you when playing. The most common way to play the Cajon is by sitting on top of it and reaching over the front to hit the face.
It is played by striking the front or rear faces with the hands, fingers or sometimes objects such as sticks or mallets. Where you hit determines the tone that is produced.
Even though the Cajon may look very simple, the tones you can achieve from it is quite remarkable. Basically, you can hit anywhere on the tapa, and you will produce a unique sound. However, the term Cajon is also applied to other square-shaped drums used in countries such as Cuba and Mexico.
The Gome is a box-shaped drum played with both hands and feet. This drum is popular among the Gas and Asantes of the country Ghana. This drum is handcrafted out of solid Odum hardwood. The drum head is made with goat or cow skin. It has a sturdy frame with a built-in floating frame and metal press for tuning.
The drum is played on its side. In order to play the Gome, the drummer has to sit on top of the drum and play using both hands and heels of the feet. This drum produces thick warm tones and healthy bass when struck.
Pandero Jarocho (Octagonal frame drum)
The frame drum is a special type of drum whose drum head width is greater than its depth. They are usually round shaped like many other drums. However, an octagonal frame drum is a unique type of frame drum with a drum body with eight corners. This drum body or shell is traditionally constructed of oak, rosewood, ash, etc., that have been bent and joined together.
It has a single drum head that is usually made of rawhide. It is laced with eight jangling metal disks, with an animal skin stretched over one side.
There are two common methods of playing the Pandero Jarocho. One way is by alternately tapping the skin with the thumb and forefinger while jangling the disks and creating a dull beat on the skin. Another way is by running the outstretched thumb over the skin near the perimeter of the frame.
The octagonal frame drums can be found in the regions of North America.
Why Are Most Drums Round?
Many of the drums that can be found all over the world are circular in shape. What might account for the numerical dominance of round drums as compared to non-round drums?
Most drums are round because of the sound they are expected to produce. It is relatively easier to make round drums as well. Let’s look at the main reasons why most drums are round.
Drums Were Originally Made From Tree Trunks
Traditionally, drums are made from tree trunks. They are made from careful crafting and carving of tree trunks. Tree trunks come in circular shapes. This meant that it was easier to make drums round by simply carving and shaping trees that already come in circular shapes.
Most drum shells are still made of wood. The commonly used woods include birch, maple, oak and poplar.
Uneven Vibration and Distortion in Non- Rounded Drums
Drums are made round to ensure that the walls of the shell have the same relative distance and angle from each other so that the resonance of the sound can reverberate properly.
Non-round drum shells, particularly square drums, do not have the same relative distance and angle from each other. There are two opposing faces on their insides that could reflect waves against each other, causing the sound produced to be distorted.
Due to this, the sound waves that bounce around inside non-round drums are uneven and disorganized. Hence when it is struck, the waves produced will not bounce back and converge simultaneously. Due to this, these drums do not vibrate evenly.
In these drums, the vibrating membrane is also longer at the corners and shorter at the sides. The vibrations of a drum membrane that is struck carry circular waves towards the edges. If the edges are not circular, the waves will be reflected irregularly. This will result in uneven intensity patterns.
However, drums that are round have all their edges equidistant from the centre. Hence, when these drums are hit at the centre, the waves produced will bounce back from the boundary of the drum and meet simultaneously. This ends up producing a rhythmic sound. Simply put, the sound that drums make when struck resonate clearly and vibrate efficiently when the drum shells are circular.
To Prevent Damage To Plastic Drum Heads
Most drum heads are made of animal skins or plastic materials. Up until the late 1950s, the head of a drum was always made of animal skin. Nowadays, most drum heads are made of plastic.
It is relatively easy to uniformly tension a drum head over a round shape than a square shape. With round drums, the stress on the drum head material is spread out evenly, and this gives a drum its natural form.
However, it is difficult to keep tension across a non-round drum. This is because a square or octagonal shape will have some distances longer than others. This will create different tensions in various directions, which will produce poor and non-reproducible sounds.
Due to this, when plastic drum heads or skin are used on non-round drums, they will easily damage at the corners since tension will not be evenly distributed across the drum head material.
It is worth noting that the more sides a drum has, the more uneven the tension would be. This means a square drum and an octagonal drum will have more uneven tension than a round drum. Likewise, an octagonal drum will have more uneven tension than a square drum.
Can We Hear The Shape Of A Drum?
To hear the shape of a drum means to deduce information about the shape of the drum head from the sound it makes. All drums produce sound by the vibration of their membranes. This means the shape of the membrane affects the manner in which waves travel through drums.
Practically, No, we cannot hear the shape of a drum. We cannot deduce whether a drum is square-shaped, circular or octagonal from the sound we hear from it.
It is obvious that it is sound that we hear and not shapes. In the year 1966, a mathematician called Marc Kac posed the same question. There have been many mathematical computations and research into this question, all generating different and mixed conclusions.
Assuming a number of drums are being played in one room. When an experienced drummer is positioned in an adjacent room to identify the shape of the individual drums producing the sounds he hears, what will be the outcome?
Will it be possible for him to deduce the drum’s precise shape just from hearing the sound and tone being produced? It will be difficult to deduce the shape of the drum producing the sound.
The sound a drum makes when struck is determined by the membrane used, its tension, and the size and shape of the shell. The sound of a drum changes as its shape changes. However, we can have drums of different shapes that sound exactly the same.
Most people think that the body of the drum is responsible for the sound we hear. However, the membrane and its vibration create the sound we hear when struck. Drums vibrate at certain distinct frequencies called normal nodes.
The frequencies at which a drum head can vibrate depends on its shape. This means the shape of a drum affects the kind of sound it produces. However, we cannot deduce the exact shape of a drum just by hearing it being struck.
Most of the varieties of drum options available in most parts of the world are round. However, there are a few non-round drums available, such as the Cajon, the Gome and the Pandero Jarocho.
It is worth noting that sound waves produced by round drums, when struck, resonate clearly and vibrate more efficiently than non-round drums. Hence, sound waves produced in circular drums are more profound, while a square drum wouldn’t produce as many reverberations.