The one string instrument is often a simple musical instrument consisting of a single string stretched across a resonating chamber or soundboard. It has been used in various cultures throughout history. The monochord has been used for various purposes in the past, including music, acoustics, and scientific research. There are some basic techniques to play the instruments so I will briefly introduce some of the monochord instruments according to the way of playing the instrument and the context of the style of music. Although there may be some additional regional variations and local names for the instrument, here are some monochord instruments from around the world
2.1 As plucked instrument (lute)
The monochord is a Greek instrument used to study music theory and harmony. It consists of a single string on a wooden soundboard, with movable bridges. It was used by philosophers like Pythagoras to explore the mathematical relationships between musical intervals. The monochord’s principles influenced the development of other stringed instruments and continue to be used today for studying music theory.
Ichigenki is a traditional Japanese musical instrument. It is one of the oldest and most ancient instruments in Japan. To play the Ichigenkin, the musician plucks the string with the fingers or a plectrum, producing a delicate and melodious sound. Due to its single-string design, the Ichigenkin is a monophonic instrument, meaning it can only produce one note at a time. However, skilled players can use various techniques such as bending, sliding, and glissando to create expressive and ornamented melodies.
Video example click here
Kse diev is a Cambodian instrument. It has a gourd attached to a stick as a resonator, with a nylon cord tied on both sides of the stick as a nut on the guitar. The musician holds the gourd on the chest with the left hand, and presses the string in a way similar to playing a violin to change the pitches, while simultaneously opening and touching the gourd to create the sound filter. The right hand holds the other side of the stick and plucks the string.
Indian ektara: it is the term about instruments consisting of one string attached to a gourd, coconut, wood or metal resonator. There are several different types of ektare: gopi yantra, tumbi and tuntuna.
Gopi yantra: The string is usually made of gut, nylon, or metal, and is plucked with the fingers or a plectrum to produce sound. Ektara players often use one hand to play the string while using the other hand to press the string against the fret, effectively changing the pitch.
Tumbi: It is relatively small in size. It consists of a wooden stick or neck, a resonator made from a gourd or metal, and a single steel string. The string is plucked with the index finger or a plectrum to produce sound. Tumbi players often use techniques like bending and sliding the string to create expressive and melodic patterns. Its distinctive and twangy sound adds a characteristic flavour to Punjabi music, and it is commonly used to provide catchy and rhythmic accompaniment to Bhangra dance performances.
Tuntuna: It is less common than other traditional instruments. It consists of a hollow wooden body with a long, slender neck. The metal string tied to a small piece of stick passes through the centre of the skin. The string is plucked with a small piece of stick held in the right hand. Tuntune provides drones and also rhythm. Players often use techniques such as bending and sliding to create expressive and vibrant musical phrases.
Khawmak (katho,a.k.a. khamak, khomok, gub-gubi, anand lahari, Bugchu or gholtong) is a folk instrument found in various places in India. It is close to erktara but it doesn’t have bamboo used to stretch the string. The basis of this instrument is a small drum, whose batter head is penetrated with a small string or cord that is attached to a handle. This handle is used to pull the string tight, changing the pitch, and the sound is produced by plucking the string.
Diddley bow (cigar box guitar): musical instrument with African roots. It is considered one of the earliest forms of the slide guitar. The diddley bow has played a significant role in the development of various musical genres, particularly in blues and African-American folk traditions. Players of the diddley bow create sound by plucking with the finger or plectrum and sliding a hard object, such as a glass bottle or metal slide, along the string. This technique allows for different pitches and tones to be produced. Due to its simplicity, the diddley bow has historically been crafted from common household items, making it accessible and easy to construct.
Dan bau is a Vietnamese instrument which I will cover in details in the next chapter
2.2 Struck on the string
For this group, I would present the musical bow, because it had numerous variations of this instrument. Depending on the culture, the way of playing that will be different, but in most of the videos I found the most common way is using the stick to hit the string. Musical bows are used as a traditional instrument in many areas of Africa. The basic structure was inspired from the hunting bow. It consists of a string tied to both sides of the bow, and resonated by using the mouth (mouth bow), or a hollowed object like a bowl, a gourd, or even ground, in order to produce the audible sound. Based on the type of resonator they employ I would group these instruments into 3 different groups.
The first group (mouth bow) uses the mouth as a resonator and changes the timber of the sound by changing the shape of the mouth. One example for that would be the Mongongo instrument in Gabon area (or M’Gongo in Baka).The position of the mouth is on one side of the string, the left hand uses the short stick to shorten or lengthen the string (in a way we use finger on, for example, violin) and the right hand uses a long, thin stick to hit the string to and trigger vibration. In another version the position of the mouth will be on the bow as the n!aoh (in Kxoe language) instrument of San people in Botswana. The musician uses the stick to hit the string made by steel or sinew. Some relative instruments are “onkhondji”, Mucope, Angola or other named as “ekweya-kweya” among Muhumbi, Agola “elumba” among neighbouring Momwhila, “ekolowa” among Hanya …. Somewhat similar to that is a Chizambe from Mozambique – the mouth is used as a resonator, but the sound is produced differently. The bow of the chizambe has small incisions in it, and the stick is being rubbed over them, producing the sound.
The second group is using objects as resonators. The resonator could be held on the belly, chest or close to the shoulder. I would first mention the kalumbu – a Zambian instrument. It is a braced instrument bow with a gourd resonator. A stick is lashed to the metal string with the left hand and players are using the right hand to touch or press it to change the pitch. Additionally, moving the gourd toward or away from the player’s belly adds the filter effect. Similar to Kalumbu is berimbau  (originally from Africa, but now commonly used as a traditional musical instrument from Brazil) primarily associated with the Afro-Brazilian martial art and dance form known as Capoeira. The player’s left hand often uses a small coin or stone touching the string to get the high pitch. In practice, berimbau is often used together with the percussion instrument called caxixi, which is held with the left hand together with the bow. The stick held with the right hand is used to hit the string, and these vibrations are transferred to caxixi as well, creating two sounds. The related instruments are “Malunga” of Siddi people, “uhadi” of Xhosa people, ‘thomo’ of the Basotho people, “umuduri” at Burundian and Rwandan, umakweyana of Zulu people…
Moreover, there is an unbraced musical bow using a gourd resonator such as “ugubhu” of Zulu speaking people, or Limbindi of Baka people. They use one long string which they tie to 3 different positions on the bow. They touch the longer part of the string with their chin to change the pitches. Right and left hand pluck the string to create the rhythm and the sound resonates by using boxes made of different materials.
The third group (ground-bow, earth-bow) uses a hole in the ground as a resonator. It consists of a flexible stick planted into the ground with the string attached to the other end. The string is then connected to a board that covers the pit, which acts as a resonator. In different cultures and/or areas it has different names such as angbindi of Baka people, kalinga or galinga of Venda people, gayumba in Haiti, Dominican Republic, tumbandera in Haitian traditions of Cuba… A version of this type of instrument is used by the Muong people in Vietnam. It is called trống đất, and consists of a long string tied between the two sticks. Third stick is used in the middle of the string, to connect it to the bamboo sheet which is covering the hole in the ground, thus acting as a resonator. The sound is produced by hitting the string with another stick.
2.3 Some bowed instruments
Gusle (in Serbia) or lahuta (in Albania) is a traditional instrument of Bosnia and Serbia. Its wooden resonator box is covered by animal skin. The bow is pulled over the string and the musician holds the instrument by their knees while sitting and playing.
Gonje is one of many names such as goge or goje (Hausa, Zarma), gonjey (Dagomba, Gurunsi), gonje, (Mamprusi, Dagomba), njarka (Songhay), n’ko (Bambara, Mandinka and other Mande languages), riti (Fula, Serer)… mostly played in west Africa. It consists of a round resonator box and a string connected from the bridge on the soundbox to the neck.It uses a bow to create the sound. Another instrument with a similar structure used by the Tuareg people in Africa, is called imzad and in general, has a bit bigger resonating box than Gonje.
Some other related instruments are: rebab – an ancestral string instrument used in Morocco, orutu – played in the western part of Kenya, specifically from Luo-Nyanza, masenqo – from the musical traditions of Ethiopia, apache fiddle – used by the indigenous Apache people of the southwestern United States, Umkiki – an instrument of Sudan people, Aduwag-ay – used by group B’laan (also called as kugot by Agusan -Manobo or duwagey by T’boli) Filipino, and tromba marina – used in medieval and Renaissance Europe…
Keyed Monochord The instrument was invented in the late 1800s by Joseph Poussot.The first models were diatonic but later he made chromatic versions as well. It has a sort of mandolin body with keys set on top of the string. The right hand using the bow pulls on the string and the left hand plays with the keys.
Some others: Xalam – plucked instrument from West Africa with 1- 5 strings. Rebec – a bowed stringed instrument from Europe’s medieval and early Renaissance eras with 1-5 strings.
K’ni: It is also known as the mouth violin (mouth resonator fiddle) by the Jarai people in Vietnam and Cambodia. K’ni has a simple structure but the way it is controlled is the timber of the sound by the mouth holds the small aluminum, horn or plastic (PVC) piece, which is tied with a string. The left hand presses the string to get the pitch, right hand uses the bow. During playing the mouth changes the shape to create the effect.
These monochord instruments, though simple in design, hold significant cultural and musical importance in their respective regions and have contributed to the development of more complex and diverse musical traditions around the world.
In conclusion, the phenomenon of convergent evolution has fascinatingly manifested in the development of monochord instruments across the world. Despite diverse cultures and geographical distances, humans have independently discovered and crafted these single-stringed instruments with similar principles of resonance and sound production. This convergence not only showcases the universal human inclination towards music but also underscores the ingenious ways in which people have harnessed the simplicity of a single string to create unique and culturally significant musical expressions throughout history. The global prevalence of monochord instruments serves as a testament to the shared human passion for exploring the depths of sound and music across time and space.