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A string, tied at A, is kept in tension by W, a suspended weight, and two bridges, B and the movable bridge C, while D is a freely moving wheel, density may be tested by using different strings Monochord Jeans.png
A string, tied at A, is kept in tension by W, a suspended weight, and two bridges, B and the movable bridge C, while D is a freely moving wheel, density may be tested by using different strings

A monochord, also known as sonometer[ citation needed ] (see below), is an ancient musical and scientific laboratory instrument, involving one (mono-) string (chord). The term monochord is sometimes used as the class-name for any musical stringed instrument having only one string and a stick shaped body, also known as musical bows. According to the Hornbostel–Sachs system, string bows are bar zithers (311.1) while monochords are traditionally board zithers (314). The "harmonical canon", or monochord is, at its least, "merely a string having a board under it of exactly the same length, upon which may be delineated the points at which the string must be stopped to give certain notes," allowing comparison. [2]


A string is fixed at both ends and stretched over a sound box. One or more movable bridges are then manipulated to demonstrate mathematical relationships among the frequencies produced. "With its single string, movable bridge and graduated rule, the monochord (kanōn [Greek: law]) straddled the gap between notes and numbers, intervals and ratios, sense-perception and mathematical reason." [3] However, "music, mathematics, and astronomy were [also] inexorably linked in the monochord." [4] As a pedagogical tool for demonstrating mathematical relationships between intervals, the monochord remained in use throughout the Middle Ages. [5]

Experimental use

1/1, 5/4, 4/3, 3/2, and 2/1 (in C: C, E, F, G, C') Cordado1 English version.png
1/1, 5/4, 4/3, 3/2, and 2/1 (in C: C, E, F, G, C')

The monochord can be used to illustrate the mathematical properties of musical pitch and to illustrate Mersenne's laws regarding string length and tension: "essentially a tool for measuring musical intervals". [4] For example, when a monochord's string is open it vibrates at a particular frequency and produces a pitch. When the length of the string is halved, and plucked, it produces a pitch an octave higher and the string vibrates at twice the frequency of the original (2:1) Loudspeaker.svg Play  . Half of this length will produce a pitch two octaves higher than the original—four times the initial frequency (4:1)—and so on. Standard diatonic Pythagorean tuning (Ptolemy's Diatonic Ditonic) is easily derived starting from superparticular ratios, (n+1)/n, constructed from the first four counting numbers, the tetractys, measured out on a monochord.[ citation needed ] The mathematics involved include the multiplication table, least common multiples, and prime and composite numbers. [4]

Several monochords, sharing a single resonator table Monocordiopitagoras20060330.png
Several monochords, sharing a single resonator table

"As the name implies, only one string is needed to do the experiments; but, since ancient times, several strings were used, all tuned in exact unison, each with a moveable bridge, so that various intervals can be compared to each other [consonance and dissonance]." [4] A "bichord instrument" is one, "having two strings in unison for each note [a course]," such as the mandolin. [6] With two strings one can easily demonstrate how various musical intervals sound. Both open strings are tuned to the same pitch, and then the movable bridge is put in a mathematical position on the second string to demonstrate, for instance, the major third (at 4/5th of the string length) Loudspeaker.svg Play   or the minor third (at 5/6th of the string length) Loudspeaker.svg Play  .

Many contemporary composers focused on microtonality and just intonation such as Harry Partch, Ivor Darreg, Tony Conrad, Glenn Branca, Bart Hopkin, and Yuri Landman constructed multistring variants of sonometers with movable bridges.


Two monochord instruments (marine trumpets) on display MIM String Instruments.jpg
Two monochord instruments (marine trumpets) on display

Parts of a monochord include a tuning peg, nut, string, moveable bridge, fixed bridge, calibration marks, belly or resonating box, and an end pin. [4]

Instruments derived from the monochord (or its moveable bridge) include the guqin, dan bau, koto, vina, hurdy-gurdy, and clavichord ("hence all keyboard instruments"). [4] A monopipe is the wind instrument version of a monochord; a variable open pipe which can produce variable pitches, a sliding cylinder with the numbers of the monochord marked. [7] End correction must be used with this method, to achieve accuracy.

Monochord practitioners

(1617) Fotothek df tg 0006469 Theosophie ^ Philosophie ^ Sonifikation ^ Musik ^ Musikinstrument.jpg
Guido d'Arezzo studying the monochord with Bishop Theobald. Guido d'Arezzo apprenant monocorde Theobald.jpg
Guido d'Arezzo studying the monochord with Bishop Theobald.
Medieval drawing of the philosopher Boethius Boethius.jpeg
Medieval drawing of the philosopher Boethius

The monochord is mentioned in Sumerian writings, and, according to some, was reinvented by Pythagoras (sixth century BCE). [4] Dolge attributes the invention of the moveable bridge to Guido of Arezzo around 1000 CE. [8]

In 1618, Robert Fludd devised a mundane monochord (also celestial or divine monochord) that linked the Ptolemaic universe to musical intervals. "Was it [Mersenne's discoveries through use of the monochord (1637)] physical intuition or a Pythagorean confidence in the importance of small whole numbers? ... It was the latter." [9]

The psalmodicon, a similar instrument but with a chromatic fret board replacing the moveable bridge, was developed in Denmark in the 1820s and became widespread throughout Scandinavia in churches as an alternative to the organ. Scandinavian immigrants also brought it to the United States. It became quite rare by the latter 20th century, but more recently has been revived by folk musicians.

An image of the celestial monochord was used on the 1952 cover of Anthology of American Folk Music by Harry Everett Smith and in the 1977 book The Cosmographical Glass: Renaissance Diagrams of the Universe (p. 133) by S. K. Heninger Jr., ISBN   978-0-87328-208-6. A reproduction of the monochordum mundanum (mundane monochord) illustration from page 90 of Robert Fludd's "Utriusque Cosmi, Maioris scilicet et Minoris, Metaphysica, Physica, Atque Technica Historia" ("Tomus Primus"), 1617, was used as the cover art for Kepler Quartet's 2011 audio CD, Ben Johnston: String Quartets Nos. 1, 5 & 10 (New World Records Cat. No. 80693), which is classical music that uses pitch ratios extended to higher partials beyond the standard Pythagorean tuning system.

A modern playing technique used in experimental rock as well as contemporary classical music is 3rd bridge. This technique shares the same mechanism as used on the monochord, by dividing the string into two sections with an additional bridge.


Monochord Monochord3.png

A sonometer is a diagnostic instrument used to measure the tension, frequency or density of vibrations. They are used in medical settings to test both hearing and bone density. A sonometer, or audiometer, is used to determine hearing sensitivity, while a clinical bone sonometer measures bone density to help determine such conditions as the risk of osteoporosis.

In audiology, the device is used to test for hearing loss and other disorders of the ear. The audiometer measures the ability to hear sounds at frequencies normally detectable by the human ear. Several test are usually conducted using the audiometer which will then be used to assess hearing ability. Results typically are recorded on a chart known as an audiogram.

A clinical bone sonometer is a device which tests for the risk of bone fractures associated with osteoporosis. This test, called an ultrasound bone densitometry screening, is not typically used for diagnostic purposes; it is generally used as a risk assessment tool. Testing is often recommended for those whose personal history indicates a possible high risk for osteoporosis. Testing is usually conducted by an orthopedist, rheumatologist or neurologist specializing in the treatment of osteoporosis. The patient simply places his or her heel in the sonometer, and it is then scanned using ultrasound to determine bone density. This is a fast and low-cost procedure generally lasting 30 seconds or less. Results typically are available immediately following the procedure. Two score results are possible: a T-score, which compares a patient's scan against that of a young person of the same gender; and a Z-score, which compares the scan against someone of similar age, weight and gender. The T-scores results are used to assess the risk of osteoporosis. A score above -1 indicates a low risk for osteoporosis; below -1 to -2.5 indicates a risk of developing osteoporosis; and a score below -2.5 indicates more intensive testing should be performed and that osteoporosis is likely present. The Z-score reports how much bone the patient has as compared to others his age. If this number is high or low, further testing may be ordered.

See also

Related Research Articles

<span class="mw-page-title-main">Just intonation</span> Musical tuning based on pure intervals

In music, just intonation or pure intonation is the tuning of musical intervals as whole number ratios of frequencies. An interval tuned in this way is said to be pure, and is called a just interval. Just intervals consist of tones from a single harmonic series of an implied fundamental. For example, in the diagram, if the notes G3 and C4 are tuned as members of the harmonic series of the lowest C, their frequencies will be 3 and 4 times the fundamental frequency. The interval ratio between C4 and G3 is therefore 4:3, a just fourth.

<span class="mw-page-title-main">Musical tuning</span> Terms for tuning an instrument and a systems of pitches

In music, there are two common meanings for tuning:

<span class="mw-page-title-main">Piano</span> Keyboard instrument

The piano is a keyboard instrument that produces sound when pressed on the keys. Most modern pianos have a row of 88 black and white keys: 52 white keys for the notes of the C major scale and 36 shorter black keys raised above the white keys and set further back, for sharps and flats. This means that the piano can play 88 different pitches, spanning a range of a bit over seven octaves. The black keys are for the "accidentals", which are needed to play in all twelve keys.

<span class="mw-page-title-main">Violin</span> Bowed string instrument

The violin, sometimes known as a fiddle, is a wooden chordophone in the violin family. Most violins have a hollow wooden body. It is the smallest and thus highest-pitched instrument (soprano) in the family in regular use. The violin typically has four strings, usually tuned in perfect fifths with notes G3, D4, A4, E5, and is most commonly played by drawing a bow across its strings. It can also be played by plucking the strings with the fingers (pizzicato) and, in specialized cases, by striking the strings with the wooden side of the bow.

<span class="mw-page-title-main">Harmonic</span> Wave with frequency an integer multiple of the fundamental frequency

A harmonic is a wave with a frequency that is a positive integer multiple of the fundamental frequency, the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the 1st harmonic, the other harmonics are known as higher harmonics. As all harmonics are periodic at the fundamental frequency, the sum of harmonics is also periodic at that frequency. The set of harmonics forms a harmonic series.

<span class="mw-page-title-main">String instrument</span> Class of musical instruments with vibrating strings

String instruments, stringed instruments, or chordophones are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner.

Piano acoustics is the set of physical properties of the piano that affect its sound. It is an area of study within musical acoustics.

<span class="mw-page-title-main">Piano tuning</span> Profession

Piano tuning is the act of adjusting the tension of the strings of an acoustic piano so that the musical intervals between strings are in tune. The meaning of the term 'in tune', in the context of piano tuning, is not simply a particular fixed set of pitches. Fine piano tuning requires an assessment of the vibration interaction among notes, which is different for every piano, thus in practice requiring slightly different pitches from any theoretical standard. Pianos are usually tuned to a modified version of the system called equal temperament.

<span class="mw-page-title-main">Pythagorean hammers</span>

According to legend, Pythagoras discovered the foundations of musical tuning by listening to the sounds of four blacksmith's hammers, which produced consonance and dissonance when they were struck simultaneously. According to Nicomachus in his 2nd-century CE Enchiridion harmonices, Pythagoras noticed that hammer A produced consonance with hammer B when they were struck together, and hammer C produced consonance with hammer A, but hammers B and C produced dissonance with each other. Hammer D produced such perfect consonance with hammer A that they seemed to be "singing" the same note. Pythagoras rushed into the blacksmith shop to discover why, and found that the explanation was in the weight ratios. The hammers weighed 12, 9, 8, and 6 pounds respectively. Hammers A and D were in a ratio of 2:1, which is the ratio of the octave. Hammers B and C weighed 8 and 9 pounds. Their ratios with hammer D were and. The space between B and C is a ratio of 9:8, which is equal to the musical whole tone, or whole step interval.

Stretched tuning is a detail of musical tuning, applied to wire-stringed musical instruments, older, non-digital electric pianos, and some sample-based synthesizers based on these instruments, to accommodate the natural inharmonicity of their vibrating elements. In stretched tuning, two notes an octave apart, whose fundamental frequencies theoretically have an exact 2:1 ratio, are tuned slightly farther apart. "For a stretched tuning the octave is greater than a factor of 2; for a compressed tuning the octave is smaller than a factor of 2."

12 equal temperament (12-ET) is the musical system that divides the octave into 12 parts, all of which are equally tempered on a logarithmic scale, with a ratio equal to the 12th root of 2. That resulting smallest interval, 112 the width of an octave, is called a semitone or half step.

<span class="mw-page-title-main">Music and mathematics</span> Relationships between music and mathematics

Music theory analyzes the pitch, timing, and structure of music. It uses mathematics to study elements of music such as tempo, chord progression, form, and meter. The attempt to structure and communicate new ways of composing and hearing music has led to musical applications of set theory, abstract algebra and number theory.

<span class="mw-page-title-main">Musical temperament</span> Musical tuning system

In musical tuning, a temperament is a tuning system that slightly compromises the pure intervals of just intonation to meet other requirements. Most modern Western musical instruments are tuned in the equal temperament system. Tempering is the process of altering the size of an interval by making it narrower or wider than pure. "Any plan that describes the adjustments to the sizes of some or all of the twelve fifth intervals in the circle of fifths so that they accommodate pure octaves and produce certain sizes of major thirds is called a temperament." Temperament is especially important for keyboard instruments, which typically allow a player to play only the pitches assigned to the various keys, and lack any way to alter pitch of a note in performance. Historically, the use of just intonation, Pythagorean tuning and meantone temperament meant that such instruments could sound "in tune" in one key, or some keys, but would then have more dissonance in other keys.

Werckmeister temperaments are the tuning systems described by Andreas Werckmeister in his writings. The tuning systems are numbered in two different ways: the first refers to the order in which they were presented as "good temperaments" in Werckmeister's 1691 treatise, the second to their labelling on his monochord. The monochord labels start from III since just intonation is labelled I and quarter-comma meantone is labelled II.

In music, the undertone series or subharmonic series is a sequence of notes that results from inverting the intervals of the overtone series. While overtones naturally occur with the physical production of music on instruments, undertones must be produced in unusual ways. While the overtone series is based upon arithmetic multiplication of frequencies, resulting in a harmonic series, the undertone series is based on arithmetic division.

<span class="mw-page-title-main">Moodswinger</span>

The Moodswinger is a twelve-string electric zither with an additional third bridge designed by Yuri Landman. The rod which functions as the third bridge divides the strings into two sections to cause an overtone multiphonic sound. One of the copies of the instrument is part of the collection of the Musical Instrument Museum in Phoenix, Arizona.

<span class="mw-page-title-main">Mersenne's laws</span> Laws describing the frequency of oscillation of a stretched string

Mersenne's laws are laws describing the frequency of oscillation of a stretched string or monochord, useful in musical tuning and musical instrument construction.

<span class="mw-page-title-main">3rd bridge</span>

The 3rd bridge is an extended playing technique used on the electric guitar and other string instruments that allows a musician to produce distinctive timbres and overtones that are unavailable on a conventional string instrument with two bridges. The timbre created with this technique is close to that of gamelan instruments like the bonang and similar Indonesian types of pitched gongs.

A third bridge can be devised by inserting a rigid preparation object between the strings and the body or neck of the instrument, effectively dividing the string into distinct vibrating segments.

<span class="mw-page-title-main">Scale of harmonics</span>

The scale of harmonics is a musical scale based on the noded positions of the natural harmonics existing on a string. This musical scale is present on the guqin, regarded as one of the first string instruments with a musical scale. Most fret positions appearing on Non-Western string instruments (lutes) are equal to positions of this scale. Unexpectedly, these fret positions are actually the corresponding undertones of the overtones from the harmonic series. The distance from the nut to the fret is an integer number lower than the distance from the fret to the bridge.

<span class="mw-page-title-main">Interval ratio</span> In music, ratio of pitch frequencies

In music, an interval ratio is a ratio of the frequencies of the pitches in a musical interval. For example, a just perfect fifth is 3:2, 1.5, and may be approximated by an equal tempered perfect fifth which is 27/12. If the A above middle C is 440 Hz, the perfect fifth above it would be E, at (440*1.5=) 660 Hz, while the equal tempered E5 is 659.255 Hz.


  1. Jeans, Sir James (1937/1968). Science & Music, p.62. Dover. ISBN   0-486-61964-8.
  2. Dr. Crotch (1861-10-01). On the Derivation of the Scale, Tuning, Temperament, the Monochord, &c. JSTOR. The Musical Times and Singing Class Circular.
  3. Creese, David (2010). The Monochord in Ancient Greek Harmonic Science, p. vii. Cambridge. ISBN   9780521843249.
  4. 1 2 3 4 5 6 7 Terpstra, Siemen (1993). "An Introduction to the Monochord", Alexandria 2: The Journal of the Western Cosmological Traditions, Volume 2, pp. 137-9. David Fideler, ed. Red Wheel/Weiser. ISBN   9780933999978.
  5. Its common use is attested to by illustrations such as this one from an 11th century Norman manuscript: "Hybride tenant un monocorde et chantant" Musiconis Database. Université Paris-Sorbonne. Accessed January 5, 2018.
  6. "Definition of BICHORD". Retrieved 2023-02-19.
  7. Barbour, J. Murray (2013). Tuning and Temperament: A Historical Survey, p.xlviii. Dover/Courier. ISBN   9780486317359. Barbour uses quotes around "what might be called a 'monopipe'".
  8. Dolge, Alfred (1911). Pianos and Their Makers: A comprehensive history of the development of the piano from the monochord to the concert grand player piano. Covina publishing Company.
  9. Gozza, Paolo; ed. (2013). Number to Sound: The Musical Way to the Scientific Revolution, p.279. Springer. ISBN   9789401595780. Gozza is referring to statements by Sigalia Dostrovsky's "Early Vibration Theory", p.185-187.