Why is the Augmented 4th the "chord of evil" that was banned in Renaissance church music? | Notes and Queries (2023)

Why is the Augmented 4th the "chord of evil" that was banned in Renaissance church music?

• IN THOSE days composing music was very much an act of praising God. The music should therefore be beautiful and moving. The Augmented 4th, or Tritonus, which spans three whole steps in the scale, is one of the most dissonant musical intervals around. It was considered unpleasant and ugly, and was named "diabolus in musica" - "the devil in music" - and you wouldn't use anything diabolical to praise the Lord, would you?

  Lars Fahlin, Anderton, near Chorley, Lancs.

• HARMONIES are created by notes sounding together at frequencies which are in proportion to each other. The proportions can be expressed by numbers. Low numbers produce consonant harmonies, and higher numbers give rise to dissonance. For example, if two notes an octave apart are sounded together, the frequency of the upper note is exactly double that of the lower. In numerical terms, upper doh over lower doh = 2:1. The sound is clear, pure and open. Sound sol above doh (the perfect fifth) and the proportion is 3:2. This sound is brilliant, confident. Sound fa over doh (the perfect fourth) and this gives 4:3. The word "amen" is often set to these notes. These two intervals are inversions of each other: doh above sol gives 4:3 and doh over fa gives 3:2. Mi over doh (the major third) is 5:4, a lovely interval expressing warmth, gentleness, "togetherness" and much more; its inversion, doh over mi (the minor sixth) gives 8:5, a curiously astringent but also beautiful interval. Doh over la (the minor third) gives 6:5; and la over doh (the major sixth) gives 5:3 - two more beautiful harmonies. Over-simplifying things: these, and a few other intervals, provide the structure, the skeleton, on which most Western music since the Renaissance is supported.

  The augmented fourth, sometimes called "the devil's interval", is created by sounding ti (or si) over fa, which notes are in the proportion 45:32. Looked at in conventional terms, the inversion of this harmony, fa over ti (the diminished fifth), ought to be identical to the augmented fourth - but its numerical proportions turn out to be 64:45. Either way, it sounds pretty ugly, though it can work musically in the right context - and it is very successfully employed in emergency sirens. This interval is fiendishly difficult to sing. The further we depart from 1, the more we move away from harmony and into dissonance.

  David Goymour, Battersea, London SW11.

• THIS chord was banned because it was very hard to sing.

  Rachel Bates, Glasgow.

• THERE are two factors. First is the background. This concerns the universal 'stability' of the so-called 'perfect fifth'. When you blow a pipe of any sort, blowing harder gives you higher notes. To start with, you get an octave, then a perfect fifth, then another octave. A series of four different pitches, three of which are really the same note, and one, the 'perfect fifth' different. But sounding very tranquil and stable, and used everywhere in the world. It gave two intervals, the perfect fifth (from the octave up to the fifth) and the perfect fourth (from the Fifth up to the next octave). Around the ninth century there developed the first form of 'harmony' in the west, which consisted of a tune note, with the 'harmony' note a parallel fourth or a fifth Second there is the context. In the days when the 'octave' really did repeat on the eighth note (as opposed to now, when it repeats on the thirteenth!), the only way you could get a different scale was to start on a different note. The scales, or 'modes', each had their own sound and feel, and melodies such as those in Gregorian Chant were made up of notes from just one of them. They all worked except for the scale you get if you play from B to B. This so-called Locrian mode was the only one where the fifth note was not a perfect fifth. It went against everything music appeared to stand for, and was christened 'diabolus in musica' the devil in music, and never used. But there is an interesting footnote to this. The problem led to adjustments at both ends of the B to F devilish interval. Composers either flattened the B until it was a perfect fifth below F, giving us the new note 'B flat', or they sharpened the F until it was a perfect fifth above the B, giving us the new note 'F sharp'. Among other things, this meant that a G major scale could now be played (using F sharp instead of F) and so could an F major scale (using B flat instead of B). And that's how harmony began, folks.

  Conrad Cork, Leicester (author of "The New Guide to Harmony with Lego Bricks").

• MORE accurately the Diabolus in Musica, the augmented fourth was the only augmented interval that appeared in the modes used before the emergence of the major and minor scales. Using only the white keys on a piano, the interval of F natural to B natural is the only augmented one (also known as the tri-tone) and was considered so unnatural and discordant in pre-tonal times as to be known as the Devil in Music. Oddly, the inverted chord of B to F (the only diminished interval in the modal syste was not stigmatised in quite the same way, although use was avoided.

  James Huggon, Knodishall, Suffolk.

• THE augmented 4th (the interval between the two tones of a fire-engine klaxon) exerts its unsettling effect even when the notes are sounded in succession and in conventional harmony and counterpoint, its use is still subject to rules and regulations. While the interval, used judiciously, gives vigour and interest to what would otherwise be rather anodyne melody, the churchmen thought its disturbing effect "apt to provoke lewd and libidinous thoughts". Naturally the ban ensured that the augmented fourth became a favourite device of church composers, and much later it was re-invented, labelled "flattened fifth" and somewhat overused by young jazz players anxious to dissociate themselves from traditional styles.

  Robin Dow, Audley, Cheshire.

• The augmented fourth interval became the hallmark, in the '40s and '50s of the type of jazz known as Bebop, whose exponents called it 'the flattened fifth'. Jazzmen of that era also had a hand sign which consisted of a high five but with the thumb folded in to the palm. This gesture, used as a greeting between jazzers, was known as 'the sign of the flattened fifth' and was often accompanied by expressions such as Oolya Koo, man! Perhaps this explains why jazz has been called 'the devil's music'.

  Pete Wigens, Stroud, Glos UK

• This musical interval, also known as a tritone, is part of the so-called Tristan chord, from its occurrence in the prelude to Wagner's opera Tristan und Isolde. In this instance the chord consists of the notes F, B, D sharp and G sharp, where the F and B constitute the tritone. Because of the ambiguity of key that results, many regard the Tristan chord as heralding the atonality employed by 20th (and 21st) century composers.The tritone features prominently in Michael Tippett's second symphony, while an earlier use can be heard in Beethoven's Piano Sonata No. 18 – which is not in the least diabolical, it has to be said.For those wishing to pursue this topic further, Wikipedia has an excellent analysis of the Tristan chord.

  Pete Wigens, Stroud, Glos, United Kingdom

• This interval was banned from church music because of its sound but is heavily used in death metal music.It is very hard to sing unless the vocalist employs a false chord technique, also known as a scream or a growl which is often used in death metal music.Death metal music is not something that is directly related to the devil. In our world, these exists two basic moods and sounds, one of beauty and one of which is ugly. The augmented 4th is the perfect choice of interval to express the later mood.

  Schubert Cardozo, Bombay, India