Pitch Definition
Pitch is the perceptual property of sound on a logarithmic frequency scale, it is the quality that permits the judgement of a sound being higher or lower.
Naming Scheme
- There are 7 repeating groups of pitches, called Pitch Classes, labeled using alphabets A B C D E F G.
- However, there are total of twelve different pitches within each repetition, meaning that there are (12 - 7 = ) five pitches per repetition that does not directly land on an alphabet.
- Other than E-F, B-C which are next to each other (this relationship is called Semitone), all other pitch classes have a note in between them (this relationship is called Whole tone).
- To access the in-between notes, we use name modifiers called Accidentals after the pitch class to alter the actual pitch of the alphabet:
Flat (b) = -1：
1Sharp (#) = +1：
1Double Sharp (x) = +2：
1Natural = 0（To nulify the effects of previous accidentals）：
1 Appears only on staff。
They can be used stackingly.
- Because of the existence of accidentals, every pitch may have more than one name. The same pitch with a different name is called Enharmonic.
Study Guide
Naming Scheme
- For historical reasons we like to arrange them as C D E F G A B.
- For more concrete understanding of the concept, we are only dealing with equal temperament here, meaning that the distance between any adjecent pair of notes is the same logarithmically.
- The best way to internalize this pattern is to visualize the piano keyboard.
- It is vital to distinguish between pitch classes and modifiers - it will be the difference between comprehension and memorization of anything related to pitch, including but not limited to intervals, counter point, and harmony. One way I would like to think of is to label all 12 notes of a repetition by their pitch number, starting from c = 0, and d = 2. To get to the pitch of 1, we can either +1 from 0, or -1 from 2. This way, not only we have less to memorize initialy, we also will not be confused when confronting scores with triple sharps
or triple flats 
. - Enharmonics does not mean the same note. It may or may not be the same pitch depending on temperament of the instrument (woodwinds and brass are mostly tuned by natural harmonic series rather than equal or just temperament). For example, D double flat - Dbb, which means D with an accidental of -2 in value, is the enharmonics of C, however Dbb belongs to the pitch classes of D while C belongs to the pitch classes of C.
Frequency <-> pitch
Just for reference, the frequency of a pitch doubles every repetition. For example, let pitch A be assigned to the frequency of 440Hz, when we get to the next A after tone repetition of the pitch classes, the frequency will be the doubling of the initial one, which will be 880. Double it again and we get 1760. Then because there are 12 pitches within each repetition, to go up by one semitone we multiply the frequency by the 12th root of 2.
As the graph shows, the distance between each semitone in Hz gets larger as the pitch raises. In order to keep the distance between pitches the same across all frequency ranges, we need to be using a logarithmic scale.
Explanation
Although pitch name is the most fundamental concept in music theory, it separates those who are capable of designing functional music and those who are merely replicating. There are too many rudimentary theory books, articles, or even plugins that emphasize on the twelve notes of the equal temperament, while great for coloration of harmonic space or serial music, lacks the logic of the note relationships due to that function music revolve around the diatonic scale. Some even encourage hardcore memorization, failing to realize that memorization is only the result of understanding and experience, and should not be the means of learning.
Instead of the 34 “fixed” pitch names with no direct relationships between each other as some proposes, memorizing the seven alphabet characters should be much easier if not innate, any other note is just an an accidental away. Accidentals are modifiers by nature, they shouldn’t ever be considered as a fixed part of the pitch name. With this mindset, we are throwing “counting semitones” out of the window, and will have very solid understanding of intervals and chord structure.