By Finlo Rohrer BBC News Magazine

The Devil is said to have the best tunes, but what do they sound like? A new film about the history of heavy metal highlights the so-called Devil's Interval, a musical phenomenon suppressed by the Church in the Middle Ages.

On the surface there might appear to be no link between Black Sabbath, Wagner's Gotterdammerung, West Side Story and the theme tune to the Simpsons.

But all of them rely heavily on tritones, a musical interval that spans three whole tones, like the diminished fifth or augmented fourth. This interval, the gap between two notes played in succession or simultaneously, was branded Diabolus in Musica or the Devil's Interval by medieval musicians.

A rich mythology has grown up around it. Many believe that the Church wanted to eradicate the sounds from its music because it invoked sexual feelings, or that it was genuinely the work of the Devil.

It is a mythology much beloved of long-haired guitar wizards.

In the newly-released documentary Metal: A Headbanger's Journey, bassist Alex Webster of death metal act Cannibal Corpse pays tribute to the effect of the forbidden "Devil's note" on heavy metal.

THE TRITONE IN MUSIC C F# The two notes, sounded simultaneously, in musical notation Hear the tritone in West Side Story's Maria

And rock producer Bob Ezrin pronounces: "It apparently was the sound used to call up the beast. There is something very sexual about the tritone.

"In the Middle Ages when people were ignorant and scared, when they heard something like that and felt that reaction in their body they thought 'uh oh, here come the Devil'."

It all sounds a little like the plot of a far-fetched Da Vinci Code sequel.

But Professor John Deathridge, King Edward professor of music at King's College London, says the tritone had been consistently linked to evil.

"In medieval theology you have to have some way of presenting the devil. Or if someone in the Roman Catholic Church wanted to portray the crucifixion, it is sometimes used there."

But there were musical treatises and sets of rules produced that did come to forbid the use of the interval, which was seen as wrong when it came up in choruses of monks.

"There are strict musical rules. You aren't allowed to use this particular dissonance. It simply won't work technically, you are taught not to write that interval. But you can read into that a theological ban in the guise of a technical ban."

Wagner a fan

The Devil's Interval enjoyed great popularity among composers in the 19th Century, when "you have got lots of presentations of evil built around the tritone".

It just sounded right - I didn't think I was going to make it Devil music Black Sabbath's Tony Iommi

"It can sound very spooky. It depends on how you orchestrate. It is also quite exciting," says Professor Deathridge. "[Wagner's] Gotterdammerung has one of the most exciting scenes - a 'pagan', evil scene, the drums and the timpani. It is absolutely terrifying, it is like a black mass.

"There is a big connection between heavy rock music and Wagner. They have cribbed quite a lot from 19th Century music."

A more modern advocate of the tritone is Black Sabbath - the rock outfit led by Ozzy Osbourne - particularly in their signature song, Black Sabbath, a milestone in the genesis of heavy metal.

But this link between heavy metal and musical conjuring of the Devil in the Middle Ages comes as a bit of a surprise to the band's guitarist, Tony Iommi.

"When I started writing Sabbath stuff it was just something that sounded right. I didn't think I was going to make it Devil music," Iommi tells the Magazine.

'False music'

He says he was aiming for "something that sounded really evil and very doomy" but admits he may have been unconsciously influenced by other music and was certainly not aiming to summon the Devil.

Sabbath's Tony Iommi was not attempting to invoke the Devil

"Beforehand [we were doing] jazzy blues. It certainly wasn't something I thought about - I didn't read music. I had no terms for anything

"I like all sorts of classical stuff - various sorts of music, jazz, blues, to classical played a big part in my writing."

There are, however, plenty of bands who consciously use tritones, including the notorious metal act Slayer, who offered their tribute in an album simply entitled Diabolus in Musica.

But Anthony Pryer, who runs a postgraduate course in historical musicology, believes heavy metal bands have got the wrong end of the stick "firmly with both hands".

"It was recognised to be a problem in music right back to the 9th Century. It is a natural consequence, and so they banned it. They had rules for getting around it.

DEVILISH EXAMPLES Beethoven's Fidelio Wagner's Gotterdammerung West Side Story's Maria Simpsons theme tune Jimi Hendrix's Purple Haze

"It was called Diabolus in Musica by two or three writers in the medieval or renaissance [period]. It was 'false music', the intervals weren't natural.

"They may have thought it was devilishly hard to teach the singers not to sing it. I don't think they ever thought of it as the Devil dwelling in music.

Now the Devil's Interval has a natural home in many genres, particularly film music, jazz and blues, where, says Mr Pryer, it is "quite common because of its association with tension and sinister things".

"A lot of films have what musicians call Captain Tritone in them. As soon as there is a [baddie such as a] foreign officer out comes the Tritone. It's a sort of badge - here's Mr Nasty. What's going to happen?"

Spooky feel

Dissonance does provoke a strange feeling, Mr Pryer says, but it is nothing to do with Satan.

Wagner provided the inspiration for some heavy metal

"[Dissonance] is something that yearns to be resolved. A very good example would be the opening of West Side Story, Maria. It wants to resolve into the next note. It is a special kind of tension. It gives that angular, edgy, spooky feel. Film music is often extremely sophisticated at signalling to a listener here is a particular kind of character. It is a leitmotif, first used by Wagner."

Whatever the real story of the Devil's Interval, the romantic linkage between Lucifer and popular music will continue, and stretches back from heavy metal through the Rolling Stones to Robert Johnson and beyond.

Mr Pryer cites Giuseppe Tartini, an 18th Century violin virtuoso who composed the Devil's Trill Sonata, a piece so complicated many modern players struggle to master it.

"He did this incredibly difficult [piece] and claimed in a dream he had heard the devil giving him instructions how to do it.

"Two centuries later, he would probably have been in a heavy metal band."

Metal: A Headbanger's Journey is in cinemas from Friday, 28 April.

When I was having voice lessons I learned the augmented 4th by remembering "Maria" from West Side Story, so I am glad this was mentioned. Incidentally, West Side Story is also useful for other intervals, notably min.7th ("There's A place for us...").
Lucy Jones, Manchester

The church, in the days when sacred music was the only tolerated kind even before troubadours 'secularised' it, was very strict on all parts of music. Much of this, as in this case, was based on the premise that certain intervals, chord progressions etc were not compatabile with holiness. The article doesn't mention the fact that this interval, when used in Wagner's case, was known as the Tristan Chord (since it was used in his Tristan und Isolde). Its inability to defined in conventional, diatonic harmony meant it was dubbed 'the breakdown of tonality', eventually leading to serialism and other forms of music not centred in a key.
Andy, Nottingham

My heavy metal heritage reminds me that "Black Sabbath" the song starts with (after the rain & the doom-laden church bells, naturally) a dirge-like riff that goes from G to G an octave above to C#. G & C# are the diabolic three whole tones apart and thus playing these notes at extreme amplification on an electric guitar can result one or all of the following; 1/ The appearance of Lucifer
2/ Be-denimed and patchoulied hordes raising their hands and making the "devil's horns" in the general direction of the artist
3/ An ASBO; and most amusingly (I witnessed this myself at a Black Sabbath gig in the early 80's)
4/ The explosive malfunction of a dry ice machine resulting in a lump of dry ice being deposited down the back of the drummer's shorts
David Birch, London

There certainly is comething very unhealthy about some tritone use eg Gotterdammerung - it had an addictive and negative effect on me at a bad stage of my life and I changed for the better and felt much less anguished when I discovered "Lohengrin" and Elgar's "Dream of Gerontius". Having said all this I think all Devil music and rap is basically spiritual evil without quibbling about exact musical style - we have enough evidence of evil in our society and need a Christian musical influence as in our "Manchester Passion" event on Good Friday.
K Watson, Stockport, UK

I never realised that this interval had a name, but in Black Sabbath, it sounds fabulous. It's particularly briliant in this piece of music, because the long slow start to Sabbath is followed by an extremely fast second part and what a contrast! If you've never listened to it, try it, but give it a chance...
Steve Karlsen, Reading, Berkshire, UK

The expresion in full is "mi contra fa, diabolus est in musica". In modern terms this a major 3rd against an 4th. They certainly discouraged this! The "Sound of Music" gets it almost right, but the mediaeval scale "ut" re, mi, fa, so, la (no seventh) and this sacle explains our word "Gammut", from the Gamma (lowest note you could sing) to the "ut", the highest ie - the whole lot. False Music "musica ficta" is nothing to do with the augmented 4th - it is a mediaeval way of describing what we would call "accidentals" that were so obvious to contemporaries, it was a waste of time marking them Result - much mediaeval English music is not performed as it was intended when put into musical notation that people understand today!
Mark, London

Music has a powerful subconscious effect, and certain notes can invoke certain internal reactions within the listener they may not be aware of. I wonder how many other 'Devil's Internals' there are, and what effects they have.
Elaine O'Neill, Surrey, England

I'm glad Mr Pryer took care to point out that the interval has nothing to do with Satan, I was beginning to worry that watching the Simpsons may lead to visitor calling from the Underworld.
Andy, Southampton, England

Never mind the tritone, some music scholars even thought the major scale was the devils work! Belive it or not, but the notes behind such diabolic tunes as 'doh a deer' and 'row row row your boat' was once considered satanic. Aparrently it made you want to do naughty things, and so was dubbed 'the lustful scale'. Funny thing is, it's now been the basis of western music for at least five hundred years, and what once was 'pagan' and degenerate was soon used to compose many religious songs/masses, nursery rymes and folk songs. It kind of reminds me of how ragtime and jazz were viewed not so long ago.....
Shane, London

How apt that you asked for "Professor Deathridge" to comment.
John Turner, Oxford, UK

It can also sound very sweet and distinctly non-evil when used in a lydian scale. Witness Ben Folds 5 "Smoke" for a good example or "Holiday" by Madonna.
Stephen Grainger, Notts

You can also hear this quite clearly in Mussorgsky's Night on a Bare Mountain. Worth a listen, purposely used as music for the Black Mass sections.

Anyone who says Heavy Metal is devil worship really doesn't know what they are talking about. At worst, it's hard, heavy and fast. In it's purest form it demands the highest skill from guitarists and is therefore a natural progression for a lot of budding musicisns. Ask anyone who plays Guitar who Eric Clapton is, then ask them who Angus Young, Jimmy Page and Joe Satriani are. They will know them all.
Doug, Ayr

The tritone is a great musical motif and can work brilliantly, but when I was taking my music O level 30 years ago we were banned from using it because it was 'wrong'. I never did understand why something in music could be wrong, but obviously we were just being passed the same instructions as everyone else had. Long live rock and roll for freeing us from such daft rules
lee, london

It seems much more likely that the use of the tritone in Heavy Rock comes from it's origins in blues music. The ubiquitous blues scale derives much of its tonal character from the tritone at its center.
Noel, Nottingham

Tritones don't have to sound evil or demonic. When used in jazz they can sound very beautiful. For example the standard (and sometimes boring) II-V-I cadence G7 - C7 - F gets transformed into something wonderful if the C7 chord is replaced with a chord based on its Tritone - such as F#13. Ask any jazz pianist for an aural demonstration and you'll see what I mean.
Tony Jackson, London, UK

This is an amazing article. It's incredible how much history can be behind any song, even heavy metal ones. I'm sure musicians like me will enjoy this film.
Maria Valencia, Liverpool, UK

I don't think most people believe that the best tunes are the Devil's, the best music has always belonged to God. It'll be forever playing second fiddle to Worship music. The whole basis of modern popular music has been built up from church hymns, Music was made for worshipping God and I feel the only proper way to experience music to the full is to be singing God's praises.
Hamish Jordan, London, UK

Does the use of tritones from Classical Music in heavy rock music, make it Classic Rock?
Peter Dobson, Earls Barton

The "death metal scale" is something I've been analysing in heavy metal music, similar to this concept of the "devil's interval". It involves particular movements of powerchords built around what is now known as the Spanish scale. There's an audio example on http://audio-guitar-lessons.com/how-to-play-death-metal-guitar.html and how to play it on guitar.
Mike Beatham, Sheffield, UK

The tritone is much more flexible than its diabolic label would suggest. It has an important place in the musical Lydian and Lydian Dominant modes (scales) and contributes to the modes ethereal qualities. Similarly, the tritone's place in Blues helps convey emotion as a melody note or in a Guitar solo. The flattened-second interval, however, is evil incarnate!
Jonathan S, Edinburgh, Scotland

Interesting! I had no idea one of my favourite sounds in music is 'devilish'. It makes it seem all the more sinister listening to heavy metal music. But if the best music is in hell, that's where I want to go.
Vicky, Sheffield

Actually the tritone is prevalent in Western music of all ages. But this makes good reading I suppose for people who aren't musically aware enough to know it's bunkum.
Neil Sands, Chichester UK

At the risk of being labelled a music anorak, there's one thing far more common in a lot of popular music (and almost everything written by Wagner and co), and that's the diminished seventh (C - E flat - F# - A). The odd thing is that this is composed of two tritones. Spooky eh?
Peter, Newbury, UK

It's a classic blues sound - at first hidden in the dominant 7th chord used in most blues turn-arounds. Players like Hendrix (e.g. intro to Red House), BB King (e.g. Live at the Regal), etc. brought it out into the open. I like using it because it gets me out of sounding too melodic. I admit that it's not that easy to fit into the worship music that I play at church. Perhaps there's a reason I hadn't thought of before...
Andy Harris, Washington, DC

There is a tritone present in every dominant chord in music - and dominant chords crop up in all musical genres, from nursery rhymes to grand opera. So the tritone is everywhere in music harmony - proving that the devil has all the best tunes!
David Mead, Bath

With all this talk of Wagner's choice of chords invoking the devil, I'm surprised your article didn't mention one of the composer's most famous and ardent fans - one Adolf Hitler.
Fi, Voventry

As creationism is bizarrely making a comeback perhaps certain religious groups will start trying to outlaw the Diabolus in Musica again! I'll have to hide about 80% of my CDs!
Richard, Kingston upon Thames

Well, the Devil may have the best tunes, but heavy metal certainly can't claim the Devil's Interval for its own. Its use in the first few bars of Jimi Hendrix's "Purple Haze" predates heavy metal by several years and its use in blues by several decades. It's just more marketing hype and can only serve to inflame the opinion of those people who seem to think that a taste for metal is the first step to a life in Satanism.
Steve Cobham, Milton Keynes