You're able to read this post because you're familiar with the letters of the English alphabet and how they interact with each other to form words. To some extent, reading music requires something similar - familiarity with musical notes and how they interact with each other to form, well, music.
Of course, music is beyond notes, there are concepts like keys, staff, clef, signatures, bars, etc, that one has to understand to read music in a meaningful way. But in this post, we focus on notes as they're widely considered by many music readers to be one of the major building blocks of music.
Let's get right in.
Notes
A musical note is a representation of musical tone or sound. It can indicate pitch as well as duration of a tone. For our purpose, we'll only be discussing notes as they relate to duration.
So, what do we mean exactly when we say "duration of a tone"? We mean how long a single tone lasts or is expressed. For example, the sound la is shorter in duration than laaaaaa. This difference in duration can be indicated via notes.
The following is an ordered list of some musical note types and their symbols - British names with US names in parentheses:
Semibreve (Whole Note)
Minim (Half Note)
Crotchet (Quarter Note)
Quaver (Eighth Note)
Semiquaver (Sixteenth Note)
Demisemiquaver (Thirty-second Note)
Hemidemisemiquaver (Sixty-fourth Note)
The notes above specify durations that are related to each other by way of being multiples or fractions of each other. As we'll find out soon, the duration of all the notes listed after the Semibreve are Binary or Base 2 fractions of the Semibreve. Let's take a look at each note.
Semibreve
The Semibreve is symbolised by an open oval called an open note head. Its duration is whole (2^0 or 1), and in comparison to other notes, it is the longest.
Minim
The Minim has an open note head with a stem. Stems are drawn upwards from a note head's right or drawn downwards from its left. The duration of the Minim is half (1/2^1 or 2^-1) that of the Semibreve which is why it's also called the Half Note.
Crotchet
The Crotchet has a closed or filled-in note head with a stem. Its duration is one-fourth or a quarter (1/2^2 or 2^-2) that of the Semibreve - yup, you guessed right, that's why it's also called the Quarter Note.
Quaver
The Quaver has a closed note head with a stem that has one tail. Tails always point to the direction of the music - we read music from left to right, so tails always point to the right. The duration of the Quaver is eighth (1/2^3 or 2^-3) that of the Semibreve.
Semiquaver
The Semiquaver has a closed note head with a stem that has two tails. Its duration is sixteenth (1/2^4 or 2^-4) that of the Semibreve.
Demisemiquaver
The Demisemiquaver has a closed note head with a stem that has three tails. Its duration is thirty-second (1/2^5 or 2^-5) that of the Semibreve.
Hemidemisemiquaver
The Hemidemisemiquaver has a closed note head with a stem that has four tails. Its duration is sixty-fourth (1/2^6 or 2^-6) that of the Semibreve.
Well, The Base Note Isn't Necessarily Fixed
The previous section could give an impression that the Semibreve is the reference or base note from which other notes find their levels and durations. But this is not necessarily correct. Any note could be the reference point or base from which others can then be assigned durational values. This is one of the reasons why some musicians don't call these notes by their US names that fix the durational values of the notes by name.
To pick any note as your base and determine the durational value of the rest, the following hold true:
The base note has a position of 0.
The position of any note above the base note is the positive distance between that note and the base note in the ordered notes list: 1, 2, 3 ... x.
The position of any note below the base note is the negative distance between that note and the base note in the ordered notes list: -1, -2, -3, ... -x.
The duration of any note is 2^n, where n is the position of a note with respect to the base note: -x <= n <= x.
The position of any note with respect to the base note is log (duration). The log is in base 2.
For example, say we pick the Crotchet as our base note. The duration of the Crotchet is 2^0 = 1. Then the duration of the rest of the notes are as follows:
Note | Position From Base | Duration |
Semibreve | 2 | 2^2 = 4 |
Minim | 1 | 2^1 = 2 |
0 | 2^0 = 1 | |
Quaver | -1 | 2^-1 = 1/2 |
Semiquaver | -2 | 2^-2 = 1/4 |
Demisemiquaver | -3 | 2^-3 = 1/8 |
Hemidemisemiquaver | -4 | 2^-4 = 1/16 |