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Guidelines for composing

Expressive devices

Expressive devices have a vital role in composition and should not be thought of as merely an afterthought. Expressive devices including dynamics, articulation and tone colour (timbre) not only determine the nature of the sound but are tools for shaping a piece or movement of a piece. They can generate homogeneity (sameness) or variety within a section or create contrast between sections within a movement. They can also be used to transition between overlapping ideas.

Dynamics

This term is used to indicate the degree of loudness in the production of sound. In modern music the expressive range of dynamics has widened beyond the usual soft to loud of pp-p-mp-mf-f-ff. It is now not uncommon to see ppp or pppp to indicate even more ‘soft’ dynamics and fff or ffff for higher degrees of loudness.

Dynamics are an important device in establishing foreground (louder or more prominent) and background (more distant) relationships between ideas. They are useful to achieve the emergence and/ or building of a passage with crescendo and the effect of sound disappearing into the distance with diminuendo. The Italian terms dal niente (from nothing) and a niente (to nothing) are also used.

In this way you can have layers of sound with differing dynamic levels as with the foreground/ background idea. It is also possible to have two simultaneous layers of ideas, one of which is emerging at the same time as the other is going into the distance. These near-far techniques create a more spatial representation of the musical material.

Also consider questions of balance between the dynamic levels of instruments in ensembles. Some instruments project sound less prominently in their lower register while others become louder in their higher registers. For example, a flute playing in its bottom register will be easily drowned out by a trombone in its upper register so be careful in both the choice of instrument and the choice of register.

Dynamics can clarify or heighten phrasing and help control how a movement unfolds, whether by gradual means or by sudden shifts between musical events. In this way they are directly linked to the compositional intent.

Articulation

Articulation refers to the method of attack in the production of the sound. Instruments may be grouped into categories according to their sound production.

Chordophones rely on vibrating strings attached to a resonating body to produce sound: violin and cello for example use a bow to vibrate the string and produce sound (they can play also with pizzicato or plucked strings); harp, guitar and harpsichord rely on their strings being plucked while with the piano, the strings are struck.

Idiophones are made from naturally occurring objects which vibrate when struck or scraped: xylophone, marimba, vibraphone, cymbals, gongs and chimes are struck; rattles, maracas, bean pods are shaken, wine glasses are rubbed, guiros are scraped.

Aerophones rely on air vibrating in a column to produce sound: flutes and recorders produce sound when air passes into their mouthpiece from the lips; clarinets have a single reed in the mouth which vibrates in the column while oboes and bassoons have double reeds which vibrate the air in the column; trumpets, trombones, French horn and tuba rely on the players lips vibrating into the mouthpiece to generate air vibration in the column.

Membranophones such as bongos, tom-toms, bass drum or snare drum, have a membrane stretched over an opening which is struck or rolled with beaters or hands.

Within each instrumental group a diverse range of expression is possible using different attacks. Winds, brass and strings can all play longer or shorter sounds- strings can sustain sound for a very long time while wind and brass phrases are dependent on the player’s ability to hold enough breath for long enough. They can all articulate repeated note patterns and shorter or longer phrases through bowing or tonguing patterns.

Articulation is also an important shaping device in communicating a composer’s intent. The contrast for example between a staccato (short detached attack) and a legato (smoothly linked) interpretation of a phrase conveys an entirely different musical intent. The use of sostenuto pedal on piano or pedal on vibraphone can enhance the decay of a sound and fill out the resonance of a passage. With the right rhythmic cells short, sharp ‘percussive’ attacks for example, whether on strings, wind, keyboards or percussion can be a useful way to convey tension or aggression.

Consider the articulation in detail so that the idea is to be communicated effectively to the performer. Make sure you indicate the method of attack including phrasing, legato, staccato, pizzicato, slap pizz., slap tongue and pedalling.

Tone colour

Tone colour or timbre is the principal means by which we can distinguish between the particular quality of each individual sound- for example a clarinet compared to a violin, a vibraphone compared to a piano, a voice compared to a trumpet. This sound quality is a function of many factors:

the materials from which instruments are made such as wood, metal, skin;
the method by which sound is produced such as bowing for strings, reeds for woodwinds, mouthpieces for brass, fingers plucking a harp, wooden hammers striking metal strings on the piano and the resulting sound envelopes attack and decay cycles which each method produces;
and the unique relationship of each sound to the harmonic series.

With synthesized sound, these factors are analysed and used to replicate the distinctive qualities of each colouristic group.

It is possible to speak of groups of instruments with homogeneous sound such as a string quartet or saxophone or brass ensembles. Within these ensembles, shifts in tone colour can be achieved with the use of mutes (sordini), shifts in register, changes to the method of attack such as sul ponticello (towards the bridge) or sul tasto (towards the fingerboard) for stringed instruments.

Mixed ensembles provide a range of colours for the composer to work with. For example a combination of say piano, flute and cello brings together three differing tone colour types with the piano covering over seven octaves in range, the flute the upper end of the spectrum and the cello the lower end (with some higher if we include harmonics). Such an ensemble provides more diverse colours which can be enhanced with careful use of register.

You can also ‘build’ colour by combining or superimposing particular blends of instrumental colour not unlike the way a painter might mix an array of colours to suit the desired gradations of shading between ‘light’ and ‘dark’. Consider the combination of flute and harp harmonics to contrast the denser string sound used by Debussy in Nuages from his orchestral work Nocturnes, the combination of winds, brass and percussion in Edgar Varese’ Hyperprism or the subtle overlapping of brighter and darker instrumental groupings in Schoenberg’s Farben (Colours) from his Orchestral pieces Opus 16 movement 3. This latter example demonstrates how tone colour can be used carefully as a shaping device.

In this way tone colour can be explored as a valuable tool to establish the homogeneity of sound, for transformation or contrast between the musical ideas and as a means of projecting sound with distinguishing qualities.