Denis Smalley
Date of publication: 

Spectromorphology is a term that was first coined by Denis Smalley in his chapter Spectro-morphology and Structuring Processes, which can be found in the The Language of Electroacoustic Music book. Since then there have been numerous publications relating to this term and a number of extensions by other scholars within the field of electroacoustic music. In 1997 Smalley publicised a revision of Spectromorphology (the revision is also available in both French and Italian) in the Organised Sound article Spectromorphology: explaining sound-shapes. For the purposes of this article the focus will be on the 1997 article.

What is Spectromorphology?

Denis Smalley defines Spectromorphology as a "collection of tools for describing sound shapes, structures, and relationships, and for thinking about certain semiotic aspects - potentially analysis of a kind" (Smalley 2010: 95). These tools are intended to be used for "describing and analysing the listening experience" (Smalley 1997: 107).  Therefore, Spectromorphology can be considered a glossary of terms, within defined frameworks, that can be used to describe how one experiences specific electroacoustic musics.

Smalley states that Sprectromorphology is "intended to account for types of electroacoustic music" (Smalley 1997: 109) with a specific emphasis on music that is "partly or wholly acousmatic" (Smalley 1997: 109). Because of this, Spectromorphology is intended for specialists first and foremost, rather than for those who have little or no experience of electroacoustic music (Smalley 2010: 94).

The Spectromorphology Framework

The term Spectromorphology is an amalgamation of the terms Spectra and Morphology. Initially these two terms were separated with a hyphen in the 1986 publication, but this has subsequently been removed from the 1997 publication. It is important to note that although this article will tackle these two terms individually they are inseparable, as one cannot exist without the other.

Spectra Framework

The framework within the spectral aspects of Spectromorphology can be summarised by the Note/Noise Continuum, the Occupancy of spectral space and the spectral density.

Note to Noise continuum

Simply put, the Note to Noise continuum is how one describes the spectral content of a sound. The two antonyms act as bookends between the vast possibilites of electroacoustic sounds. The major change between the 1986 and the 1997 publication is that the term node has been dropped completely from the framework. Instead the continuum contains notes of harmonic and inharmonic content to describe variations between these two points. Smalley also adds two types of noise; granular and saturate, to describe the perceptual qualities attributed to certain types of noise.

Occupancy of Spectral Space

Smalley adopts the term spectral space to "represent the wide variety of sound-qualities, timbres and pitches perceived over the spectrum of audible frequencies" (Smalley 1997: 118). It does not relate to the spatialisation of sounds within a fixed-media piece.

There exists three types of spectral space: canopy, centre and root. Smalley states that the canopy and root can be regarded as "boundary markers" that "frame spectral space" (Smalley 1997: 121).  Smalley use the term frame to describe an empty region within a given work and the term centre to describe sounds that inhabit this space.

There are four qualifiers for spectral space, which are based on antonym pairs: 
• emptiness - plenitude 
• diffuseness - concentration
• streams - interstices
• overlap - crossover (Smalley 1997: 121).

Spectral Density

Spectral density is used to describe how sounds emanate from one another. Whether they are considered distant or close and whether they allow other sounds to be heard.

Smalley defines six types of spectral density ranging from high to low: filled, packed/compressed, opaque, translucent, transparent and empty. These types of spectral density, depending on their relation to the distant-close continuum, will either block or allow other sounds from being heard.

Morphological Framework

The framework within the morphological aspects of Spectromorphology can be summarised by the Onsets, Continuants and Terminations functions, the Motion and Growth processes, Texture motion and Behaviour.

Onsets, Continuants and Terminations functions

The three terms Onsets, Continuants and Terminations are used to describe the three morphological states within an amplitude envelope. Within each of these three states exists a number of terms to describe the way in which a sound evolves. Smalley states that these functions can be applied to micro and macro levels of musical structure to describe notes, objects gestures and textures (Smalley 1997: 115).

There have been some significate changes to the terms used within these states between the 1986 and 1997 publication as outlined by Robert Normandeau in his chapter Spectromorphology of Denis Smalley within the Denis Smalley Polychrome Portraits book.

Motion and Growth processes

Smalley uses the terms Motion and Growth as he finds traditional concepts such as rhythm "inadequate" for describing the "dramatic contours" that exist within electroacoustic music (Smalley 1997: 115). He defines three groups that should be regarded as motions: unidirectional, reciprocal and cyclic/centric; and one group that should be regarded as growth:bi/multidirectional. Within these groups exists more terminology for describing that particular motion or growth process.

Smalley also adds seven characteristics of motion to describe how these sounds function within the Motion and Growth process. These seven characteristics are: push/drag, flow, rise,throw/fling, drift, float and fly.

Texture Motion

Texture motion is used to describe the variations in the Motion and Growth process. Smalley uses four terms to describe this relationship: streaming, flocking, convolution andturbulence. He states that these four relationships may vary in "internal consistency" ranging from continuous to discontinuous motion, which he defines as the continuity-discontinuity continuum (Smalley 1997: 117). Sustained and iterative motions rest at opposite ends of this continuum with granular occupying the "ambiguous mid-point" between the two(Smalley 1997: 117).  All of these points within the continuity-discontinuity continuumcan be described as moving in the following ways: 
• periodic - aperiodic/erratic
• accelerating - decelerating - flux 
• grouping patterns


Smalley uses the metaphor behaviour to describe the "relationships among spectromorphologies acting within a musical context (Smalley 1997: 117). It is separated into a vertical and horizontal axis by motion coordination, which contains the loose-tight continuum, and the motion passage, which contains the voluntary-pressured continuum. Causality also resides within the motion passage when one sound events seems to trigger another. 'Behaviour relations are identified by two sets of antonymous concepts: dominance/subordination andconflict/coexistence. A list of relationship modes are placed in the centre to form the basis of the two concepts.

How can it be used?

Spectromorphology is first and foremost a set of terms for describing the listening process. It is not an analytical or compositional system. Instead it suggests viewpoints and tools for "speculating and imagining", but these cannot be organised into a single analytical or compositional action (Smalley 2010: 92). He also suggests that others could "supplement his basic listening with their own analogies" where appropriate (Smalley 2010: 91). 


NORMANDEAU, R. (2010) Spectromorphology of Denis Smalley. In GAYOU, E. et al. Polychrome Portraits Paris, INA-GRM, pp. 79-88.

SMALLEY, D. (1986) Spectro-morphology and Structuring Processes. In EMMERSON, S. The Language of Electroacoustic Music London, Macmillan Press Ltd, pp. 61-93.

SMALLEY, D. (2010) Spectromorphology in 2010. In GAYOU, E. et al. Polychrome Portraits Paris, INA-GRM, pp. 89-101.

SMALLEY, D. (1997) Spectromorphology: explaining sound-shapes. Organised Sound, 2(2), pp. 107-126.