Orchestral strata

We sometimes hear about orchestral, or harmonic, strata. As so often happens, in any field of endeavour, seemingly obscure and complex ideas actually exist all around us.

The idea is this: by treating large groups of sound as collections of smaller layers we not only achieve a more controllable method (especially of combining instrumental sections) but also introduce subtle changes in effect.

There’s nothing new in this. Take the simplest form of writing for an eight-piece brass section in the jazz orchestra or ‘big band’. It simply comprises one four piece ‘block’ harmony, trumpets, above another, an octave lower, from the trombones. This simple scheme, along with a few less obvious forms, was dealt with in more detail in a previous post:


Theoretically, it requires little further justification; it really works.

When, as frequently happens, we open up the trombone harmonies and/or use more active trumpet work above the more static trombones, we introduce refinements into the scheme:

The big band ensemble is another example. Typically (but not always) the brass will be in close position but the saxophones will be in open harmony, often carrying the bulk of the harmonic tension. Their richer sound enhances the effect which is to form an acoustic cradle for the brass to ‘sit’ in:

Early arrangers arrived at these schemes without ‘schools’ to guide them, which makes their novelty all the more remarkable.

Occasionally, trumpets will use simpler chords in the high register, accentuating the feeling of ‘altitude’:

They may play a simpler form, which might be, say, a chord with added sixth – or even a simple triad with optional octave doubling of the melody:

The harmonic fullness is carried down below in the trombones, or saxes and trombones. Exact doubling will be required down here to avoid stragglers in the blend, which will stick out at the expense of the surrounding parts (to cut a long story short). The compound effect will be that of the full chord, say, 13th, but the orchestral treatment introduces a different effect altogether than one that simply piles the chord upwards from the root. With smaller ensembles the latter method has to be used of course:

In the full orchestra, the present technique really comes into its own, with sections of homogenous instruments cohering together but, at the same time, combining to produce the ‘master’ harmonies.

A further and, I would say inevitable, development lies in the field of polytonality. Although the limit of this idea will be reached (in equal temperament) with a staggering twelve instrumental layers, with up to four parts in each, it’s more usual (because the listener’s auditory response has to be born in mind!) to show more restraint and limit the number of vertical strata.

It’s essential (I would say) to select equal intervals between each stratum in the compound group. Minor or major thirds (or their inverted forms) and fourths (or fifths) are easiest to manage. Chord transformations will generally be required to differ (i.e. we can’t just transpose groups from one stratum to another) because of the need to avoid overlapping but different activity between them, coupled with the effect of different tone colour, will alleviate this problem to an extent plus, as always, ‘logical’ tendencies have to be carried through in the movement of parts.

There are, as everyone knows, four minor thirds and three major thirds within the span of an octave, which can also be divided into six whole tones. These subdivisions limit the number of strata but the roots of more ambitious groups can exceed the range of the octave. Everything can be generalized, too, with semitone = 1 and building out systematically from there. The augmented fourth divides the octave exactly in half and this form of bitonality was a favourite with English comedian Les Dawson when he played the piano badly on purpose. You have to choose just the correct wrong notes for success in this area, if anyone is interested. Les was no fool. Oh, and by the way, it was used by ‘modern’ composers, too.

Although all this might seem, at first glance, to be a mechanical process, the procedure is no different to the subdivisions we all happily live with every day such as, for example, the habit of writing in the major and minor scales and the various modes, which are themselves selected from the full range of audible frequencies. In other words, strata harmony isn’t an offence.

This kind of treatment often favours an open key signature and it might also be an idea to write the score in ‘concert’ rather than transposed, especially since each stratum might be in a different key (multiple strata can be diatonic, too). Have some pity for the conductor.

The result does not need to be a succession of sustained chords. All instrumental effects ­– alberti bass, oompah figures etc. etc. – are fine:

Here’s an audio file of the above figure:

A melody will ideally be developed from the tonality of one stratum, generally, but not always, the highest, and contrapuntal schemes can be developed. To avoid the end product being hopelessly confusing, unessential notes require to be closely systemized. Pre-set patterns may be derived and I find that graphic diagrams can help keep a ‘handle’ on things and keep them tidy.

People will think you’re really clever when you present your arrangement but, to be fair, this type of architecture can be brain-wrenchingly difficult to ‘construct’. The trick is to be methodical in our working methods and not try to make too many different decisions at the same time. I find that, as I work, artistic selective processes begin to dominate, breathing ‘life’ into the music, generally in ways that would not otherwise occur.

Music written in this way can be very dissonant. The environment will form an important factor. An audience sitting in a palm court environment during a lunchtime concert will not expect to be scared to death but writing the background music for a film about a catastrophic volcanic eruption will be a different ball game altogether plus, as always, listeners differ in their musical awareness and their ability to assimilate extreme forms.

It’s a lonely business, being a composer.


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