Quartertones are the “notes between the notes,” found by dividing tempered half-steps (semitones) into equal quarter-steps. For performers, they are an entry point into a wider compositional technique called Microtonality. There are many different microtonal systems, each dividing the tonal spectrum according to a specified logic. (i.e. 1⁄3– and 1⁄6-tones, or systems built on the overtone series)
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Notation of quartertones has not been completely standardized, so many symbols have been used in the past. Most composers use some kind of alteration on the sharp, flat, and natural signs:
Here are those symbols as you might see them in practice:
A simpler way of seeing the progression of quarter-steps between F and G:
Again, since notation has not been standardized you may encounter any of the above symbols, not to mention many unique solutions conceived by composers. In 1974 a recommendation was issued by the International Conference on New Musical Notation in an attempt to simplify the symbology and create a norm for composers and engravers. They settled on the following:
These are the symbols that will be used in the remaining examples and exercises.
To learn how to hear and practice quartertones, read on: Orienting Your Ears