Essentially following common terminology, the term musical consonance is meant to denote a number of basic auditory phenomena that govern the perception and the historical development of tonal music. Hence the the term musical consonance is essentially synonymous with what Helmholtz (1863a) termed Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik. However, while Helmholtz in his time had to explore and to explain many physical and physiological details that are involved, the present concept of musical consonance is designed on top of those details, which nowadays are provided by auditory physiology and psychoacoustics.
The concept of consonance obviously implies the aspect of pleasantness. However, pleasantness, as a general psychological attribute, is not confined to musical sounds. Rather, any sound of real life can fairly consistently be rated according to its pleasantness, and its pleasantness can be distinguished from that of another sound [52]. So it is apparent that there are certain basic sensory factors that affect the pleasantness both of musical and non-musical sounds. Therefore, the collection of such factors must be considered as one aspect - or component - of musical consonance. I have termed that component sensory consonance [30], [34], [63].
As sensory consonance, by definition, was neither conceptualized nor expected to explain the essential and typical features of musical sounds, there must be another component of musical consonance which accounts for these music-specific aspects. This latter component was termed harmony [30], [34], [63].
So, most concisely, musical consonance is conceptualized as "sensory consonance plus harmony". It was only when I had figured out this two-component concept of musical consonance [30] that I fully understood that Helmholtz (1863a) had already pursued exactly the same approach. He was not much explicit about his concept (obviously, because it was self-evident to him), but his concept becomes unmistakable from both the structure and the contents of his book. What Helmholtz simply has termed consonance was by him conceptualized as representing the aspect of "sensory pleasantness". Thus this component of his theory is identical with what I call sensory consonance. And the other, most important component of musical consonance was by Helmholtz termed Die Lehre von den Klangverwandtschaften. This component was concerned with the typical relationships that exist between the tones and sounds of music. It is identical with what I call harmony. As Helmholtz's choice of labels turned out to be not quite fortunate - there occurred unnecessary misunderstandings already in his time - I prefer my own terminology as outlined above.
The two major components of musical consonance, i.e., sensory consonance, and harmony, can be described more specifically. Sensory consonance turns out to be dependent on certain basic auditory attributes, i.e., roughness, sharpness, and tonalness [52], [104] p. 403, Aures (1985a, 1985b). And harmony is essentially composed of tone affinity and root-relationship [30], [63]. So we have a hierarchical concept of musical consonance that can be illustrated by the following table:
Sensory Consonance |
Harmony |
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