Introduction to Music Theory

Here is a brief introduction to music theory. Music is a combination of melody and rhythm. In this page, I'll be dealing mostly with melody. So the rhythm aspect of music is kept in the background.

Notes
A note stands for a single pitch, or a single uniform sound associated with a particular frequency. Any melody consists of a sequence of notes.

In Western music, we have twelve different kinds of notes, lying in sequence in terms of pitch. A note is said to be higher than (or "to the right of") another, if it has a higher pitch than the other. Similarly a note is said lower than (or "to the left of") another, if it's pitch is lower than the other.

Seven of these are called "natural" notes, and are represented by letters of the English alphabet from "A" through "G". Thus the note "A" is lower than the note "B". The next higher natural note to "G" is "A", and this "A" is much higher than the previous "A" to the left of "G" (separated by F, E, D and C). The five remaining notes are called "sharps" or "flats", and lie in between the natural notes. A sharp or flat note is represented in one of two ways:

• Using the name of the natural note immediately to the left of the note, followed by a "#" symbol (pronounced "sharp")


• Using the name of the natural note immediately to the right of the note, followed by a "b" symbol (pronounced "flat")

If the sharps or flats fit in between natural notes, there should be seven sharps/flats, since there are seven places to fit them. The answer is that there is no sharp or flat note between "E" and "F", and between "B" and "C".

Notes and their frequencies

Any note, given its octave, is directly associated with a frequency. I say "associated with", because a note is not the same as a single frequency, but is a collection of frequencies out which one of the frequencies turns out to have the strongest influence on how the note "sounds". Whenever I refer to the "frequency of a note", I'm referring to this "most influential frequency" of the note.

Scales

In simple tunes, which we hum all the time, all twelve notes may not play a part. Even in complex tunes, some notes will usually occur much more frequently than others. This gives rise to the concept of a scale of notes, which is nothing but a subset of the twelve notes. A note is on a given scale if it that note is present in the scale's subset of notes.

Common scales

It is possible to construct a large number of scales using different combinations of the twelve notes. However, it turns out that some scales are more common than others. One of these "common" scales is called the "major" scale, which consists of seven notes. Once we have decided on a root note, we can find out the notes in the major scale for that root note in the following manner.

Relative minor and major

Observe that both C major and A natural minor consist of the same set of notes (except, of course that the root notes are different). This forms a relation between the notes C and A. C is called A's relative major, and A is called C's relative minor. Such relations exist for every note. The relative major of a note can be found by adding 3 semitones to that note, and the relative minor can be found by subtracting 3 semitones (or adding 9 semitones, which boils down to the same thing).

Notes and Scales in Indian and Western musicIn Western music, successive notes are equally separated (by equal frequency ratios, as discussed earlier). In Indian music this is not so. However, the notes in Indian music can be sufficiently approximated to fit into the set of twelve notes used in Western music.

The notes in Indian music are denoted by the seven notes:

Sa Ri Ga Ma Pa Dha Ni Sa
The above set of seven notes are called the Saptaswara (Sapta means "seven" and swara means "sounds").
Here, we will not go into details of the theory of Indian music. But a few similarities between Indian and Western music deserve mention here:

• Barring Sa and Pa, the rest of the above notes in Indian music can correspond to different pitches in different cases.


• The concept of root note (as in the root note of a scale, described before) in Western music relates directly to the concept of a shruti in Indian classical music.


• The concept of a scale in Western music is similar to the concept of a raga in Indian classical music.


• Given a note from the saptaswara, the corresponding note in Western music can be found only after knowing the shruti and the raga.