StringSection Blog

December, 2009

Harmonics and the Harmonic Series

Wednesday, December 23rd, 2009

All musical tones are based on the harmonic series - whether it be a length of brass pipe, a church bell or a taut length of string, all instruments are subject to harmonics. The harmonic series are a sequence of pitches relating to a lower pitch (or fundamental note,as it is often called). Therefore a sound of a certain number of vibrations will also cause overtones to resonate in a ratio to that sound eg. a 100 Hz sound will be accompanied by overtones of 200, 300 and 400 Hz,and so on. All musical sounds possess all the notes of the harmonic series and it is the way these notes are blended together that gives sounds their individual ‘timbre’ or texture. Therefore the blend of the harmonic series in an oboe is different from that on a violin.

The harmonic series has been at the heart of tuning and temperament for thousands of years, before the standardisation of pitch into what we call ‘equal temperament’. This tuning system which has only gained universal currency in the last hundred years is the least understood of all musical concepts as it has been so wholly embraced. In so doing, not only has it ironed out music into 12 strictly equal semitones (robbing it of much of it’s harmonic character) but it also goes against the natural laws of the harmonic series. This is why even the world’s finest orchestras can have irreconcilable tuning issues.

For a full explanation of this all-encompassing musical dilemma I would like to heartily recommend Ross W. Duffin’s ‘How Equal Temperament Ruined Harmony (and Why You Should Care). An organist friend of mine passionate about various tuning systems brought it to my attention it and it is scholarly, concise and a hugely entertaining read.

On all stringed istruments the harmonic series reveals itself as described above. Therefore when a string is foreshortened (or ’stopped’) by a finger the same ratios apply eg. there is a harmonic exactly half way up each string (ratio 2:1) sounding an octave above the open string. The second one is a fifth higher than that (ratio 3:2) and so on. These notes are called harmonics and can be played by touching the left hand finger very gently on the string with a fast and light bow speed (in a similar way to making a wine glass produce a pitch by running one’s finger along the rim of the glass). The note thus produced is pure, clear with a flute-like quality different from any non-harmonic notes.

Stringed instruments are also capable of producing ‘artificial’ harmonics. These mimic the tonal qualities of a harmonic but produce notes of a higher pitch than the natural note in the same way. The lower finger ’stops’ a note in the conventional way with a higher finger gently touching the string at the interval of a fourth above to produce a note two octaves higher than the lower finger. In this manner, it is possible to play whole melodies transforming the sound of the instrument into a completely different timbre.

In the context of a string arrangement, harmonics can produce an ‘other worldly’, ‘eerie’ quality that can add a real sense of mystery and magic to a piece, even when mixed in with other instruments in a track, the effect is haunting!

Counterpoint

Thursday, December 17th, 2009

Counterpoint is the art of writing individual parts that have complete melodic independence from one another yet work in harmony and compliment each other perfectly. It is a skill that comes from an advanced understanding of harmony and an innate grasp of what will sound correct. If done with imagination and flair, counterpoint can completely transform any piece of music into something rich and complex.

Fortunately, there is no computer (as yet!) that can automatically write counterpoint - it is an art that comes from a human beings inspiration.

There have been many sessions that we have been asked to provide strings on where the string parts have been sustained in nature and harmonically slightly empty (often travelling in octaves or unison with little texture in the middle). This can be appropriate where the other instruments are busy in the track but often it’s inappropriate and doesn’t fully utilise the presence of live strings in the studio. In this context, counterpoint in the form of a skillful counter melody or an interesting, moving part can provide a special feeling adding climax and interest to the string parts. When a composer is completely reliant on a keyboard and therefore bases much of the writing on blocks of chords, then the strings never really come alive. It is the presence of the individual strands which make up a beautiful, flowing whole - rather like a tapestry with different threads and colours woven through it.

If a string arranger is considering writing a counter melody (whether above the tune or in the middle register to add detail underneath), they can start by playing around with the three notes of the triad in the existing chords (in the instance of a 7th chord, this may be 4 notes). Before long, a melody will start to unfold based on these notes and eventually the shape of the melody will emerge, often through passing notes which allow it to effortlessly travel from one chord to another in a smooth succession.

Here’s an example of a string arrangement I wrote for string quartet - based on the traditional Christmas tune ‘I Saw Three Ships’. Although many carol books suggested which chords to put with it, I was happier experimenting until it felt right.

Violins: Vaughan Jones and Louise Bevan, Viola: Adrian Smith, Cello: Tony Woollard

As an example of a counter melody, at around 16 seconds in, the second violin begins a counter melody to the same rhythm as the first violin. At 29 seconds in, the viola and cello have the same motif, an octave lower whilst the upper strings have a pizzicato figure to add rhythm and life. All the lines sound pleasing when played individually. The rhythm and tune is moved around between different instruments to add interest whilst the pizzicato bridge section builds up in thickness as well as volume to add climax. At 1 minute, a new counter melody is introduced like another layer being added in the second violin, whilst violin 1 and cello are in octaves. At 1 minute 20, the tune from the second violin breaks into the first violin part to dominate the piece with the main theme becoming secondary but still discernible. At around 1 minute 40 seconds, a totally new melody emerges that now replaces the main melody all together, yet is it is still in the same style and fits the chords harmoniously. At 1 minute 56, a canon in four parts is begun where part of the theme is treated fugally, passing from one instrument to another but always overlapping and building up a busy counterpoint which ends with the cello repeating a two bar phrase. The distinctive rhythm is kept going from 2 minute 15 onwards in the cello part whilst the second violin gets the melody and the first violin has an intricate and showy folk type accompaniment - this builds up to a climax before the two violins have an identical one bar phrase in sequence and the whole piece ends with the rhythm played by the viola in an echo of the opening of the piece.

Generally writing or arranging for strings does not always have to be this busy or intricate (unless they are required to be a real focal point!) but when strings are required to stand up in their own right (without additional instruments in a track), they need to really come alive!

Session at the Engine Room

Sunday, December 13th, 2009

On Sunday the 6th December, we were booked as a string quartet comprising two violins, a viola and cello to record at the ‘Engine Room’ (part of the group of Miloko Studios in London). We were required to add simple string parts to seven tracks for an independent band - as these weren’t string arrangements that we had been asked to write, we simply had to turn up and play the music given to us on the day. The bands style favoured irregular time signatures which kept us on our toes with large sections being done in a single take to capture a live feeling of spontaneity. The end product certainly enhanced the sound with the tracks gaining richness and depth as a result of including live strings. In a couple of tracks, the producer discussed the possibility of using the tracks laid down by the four session musicians to add a top layer to existing sampled strings - this technique is becoming increasingly popular where there are many different sounds in the mix and can certainly help the strings to sound more convincing than only using samples.