excerpt from "Musical Scales in Different Cultures"
In the mid-range of hearing, humans can tell the difference between about 240 different pitches in an octave (Gill & Purves, 2009). However, if you know anything about music at all, you are probably already aware that most of these pitches are never actually used. According to David Huron (1994), “All known musical cultures make use of a select repertoire of pitches from which musical works are assembled” (p. 289). These repertoires of pitches are more commonly known as scales. Scales make up a fundamental part of music in any culture, though the way that these scales function and are used vary wildly between them. Many will sound odd to an ear that is unused to a particular one, while others will sound sweet and pleasing. These variations are very culturally-dependent. In looking at a variety of different kinds of scales from around the world, ranging from the equipentatonic scales of Central Africa to the dodecatonic chromatic scale that much of Western music is organized by, one can learn a great deal about music perception and how music can differ from culture to culture using these sets of notes. This paper will delve into many of the basics of scales, starting with the idea of universal octave equivalency and harmonics, and then move on to the different scales used around the world, how they work, and why they were formed.
There are, in fact, many universals that can be found in all the musics of the world, but when it comes to pitch perhaps the most basic is the idea of the octave. The octave is something common to all cultures, although some do treat it differently than others. In simplest terms, the an octave is an interval with a frequency ratio of 2:1. For example, if a note were to have a frequency of 440 hertz, the note an octave below would have 220 hertz, and an octave above would have 880 hertz. Around the world, there is a recognition that pitches with this kind of relationship are somehow the “same.” In the section of Kathleen M. Higgins’s article The Cognitive and Appreciative Import of Musical Universals in which she enumerates a number of universals that hold true in all music, “We perceive a tone an octave away from a given tone as effectively the same tone” (p. 489). The phenomenon of octave equivalence, as it is called, can be recognized even by three-month-old babies (Higgins, 2006). This is a strong fundamental in music everywhere.
It is interesting to note that the octave is universal when other intervals are not. Though some of these intervals are more frequent in the world’s musics, only the 2:1 ratio is treated as a commonality among all of them. Even then it is sometimes warped slightly, such as in the Central African equipentatonic scales, which will be explained later. However, scales and music in general are much easier to comprehend with the notion of the octave firmly in place, and used as a basis for all further exploration of intervals in any culture.
One the idea of the octave and octave equivalence is settled, one can begin exploring between this space. This is where things begin to get complex, and vary greatly between different cultural groups, as this is where scales are formed. However, there are many trends involved in scales that are seen throughout music of the world. Though they are not quite as universal as the octave, there are certain things that we can know to be true.
A good place to start is the number of notes in the octave in a given scale. This varies not only between cultures, but also between scales in any given culture. Take, for example, Western music’s chromatic scale compared to the major scale. These two scales serve very different functions, so it is not strange that one contains all twelve notes that exist within the octave in Western music, while the other only has seven pitches. However, neither of these concepts is unusual. Traditional Chinese music similarly uses the same chromatic scale as a way of showing notes available, while using pentatonic (five-pitched) or heptatonic (seven-pitched) scales in the actual music, just like Western music (Gill & Purves, 2009). This is not nearly as common as cultures who only use heptatonic or pentatonic scales, however. Scales with five or seven notes between the octaves are the most popular throughout the world’s music.
There are a few possible biological reasons for this. According to Higgins (2006), having five to seven pitches in an octave “is consistent with George A. Miller’s principle that our short-term memory can manage ‘7 plus or minus 2’ items of information” (p. 492). It is likely that these numbers have been chosen because it is an easy amount of information to recall as a performer and a listener. Our memory can only process this much at once, and therefore scales of these types are popular in all sorts of music everywhere. Another theory is that heptatonic and pentatonic scales generally have more approximate simple integer ratios (Higgins, 2006), meaning that the ratios of the intervals are more likely to line up nicely mathematically and therefore sound more consonant.