Rhythm and Meter
Music unfolds in time so composition-project time management is of fundamental importance in ArtSong. There are several key aspects of time management in ArtSong; these factors all contribute to rhythm:
- Specifying a base duration unit; the unit of composition time quantization,
- Setting a tempo or tempo changes; the speed at which duration units occur in time,
- Establishing a Time Signature(s) (See Tutorial 1) to create a relationship between a ‘beat’ and the ‘base duration unit’, and
- Defining a ‘meter’ specifying how duration units should group.
Base Duration Unit
ArtSong uses a ‘base duration unit’ to create a (metric) grid against which all note attack points and durations are measured.
At any point in time there is a single base duration value in effect for each component. However, this base duration value is not necessarily constant nor uniform for all components.
- Set a default or global value for the Base Duration Unit value in the Composition Component Property Editor.
- The default composition Base Duration Unit value can be changed within a composition by drawing Composition Component Events and setting a new value in the Event’s Data Editor.
- The Hierarchical-Meter and Free-Meter algorithms, located on the ‘Rhythm / Meter’ tab of the Algorithms Palette, also provide a way to set a local Base Duration Unit value. Add an instance of the algorithm to your project, add a component event at the desired location, and set the base unit value in the Event Data Editor.
Effective Base Duration Unit
Usually you will set the Base Duration Unit value to the ‘shortest’ note duration value required by your composition. For some Track components you will use this shortest value directly; for other tracks you may wish to use a different or longer ‘base duration unit’ value (referred to here as an Effective Base Duration Unit) that is some multiple of the default duration unit.
The Track component’s ‘Multiplier’ Composition Variable is provided as a means to allow you to give each track component a different effective base duration unit that can vary algorithmically.
Set a value for the ‘Multiplier’ by opening the track’s Property Editor, select the Multiplier on the Composition Parameters pages, and set a constant or ranged value. If a range is selected you will also need to assign the ‘Multiplier’ variable to an algorithm or the value will not actually change.
Meter
As human beings we have a tendency to group events as they occur in time. Naturally we therefore tend to group ‘beats’ as they occur in time. A result of this ‘grouping’ is an implicit division of beats into ‘stronger’ and ‘weaker’ beats. The pattern of strong and weak beats is referred to a Meter.
Other musical event groupings may be either in-phase with, or out-of-phase with the perceived meter. Each situation entails different musical consequences.
ArtSong provides two algorithms, Hierarchical Meter and Free-Meter (located on the ‘Rhythm / Meter’ tab of the Algorithms Palette), which can be used to assign a numerical metric strength value (0.0 to 1.0) to each composition time interval. The Track component’s ‘Accent’ composition variable directly uses this metric strength value to generate an accent value to add to the note volume value.
The Composition Component provides a ‘Metric Threshold’ value used to classify the numeric metric strength values into ‘strong’ beats and ‘weak’ beats. Several algorithms allow you to synchronize changes specifically with strong beats or weak beats.
Most theoretical treatments of meter usually involve hierarchical analysis of the ‘grouping’ tendencies of events at multiple ‘durational’ levels.
Hierarchical Meter Algorithm
ArtSong’s Hierarchical Meter algorithm provides a means to create a hierarchical grouping of note durational values and assign a numerical weighting to each level. The sum of weightings at all levels that coincide at a particular time (grid columns) are used to assign a numerical ‘metric-strength’ value to each time during the composition process.
Add a number of Metric Levels.
- For each Level: select the level by clicking on its name, use the Level sliders to set the Grouping Size and Grouping Weights.
- The number of levels and their groupings will determine the repeat length for the metric pattern
Free Meter Algorithm
ArtSong’s Free Meter algorithm allows you to directly assign numerical relative-weightings to a sequence of duration intervals.
- Set Pattern Length to the desired meter repeat length.
- For each interval set a relative weighting.
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