Recall or pop-up the definition of . This post describes the temporal aspect, called time value or note value. Rests have a time element too, so they are included in the discussion. A rest is a period of silence, there is no sound. For every note value there is an equivalent rest.
When notes of different duration are heard one after the other we get rhythm. (Usually different but not necessarily.)
The time signature tells us two important things: the number of s in a bar and the type of note getting one beat. The top number tells us the number of beats, and combined the numbers tell us the type of note getting the beat. Read 2/4 as two quarter notes per bar, 3/4 as three quarter notes per bar, 4/4 as 4 quarter notes per bar, 4/8 as 4 eighth notes per bar. If you don’t know what quarter or eighth notes are you will shortly.
The time signature does not tell us the rate at which the notes, specifically the beat, moves in time. Tempo, the number of beats per minute, does that.
How Notes and Rests get Their Name and Time Value
I’ll explain note value using 4/4, also called “Common Time” and sometimes indicated with the letter “C”, rather than 4/4. It is the most common time signature used in music, although rare in tango before Piazzolla. I have to use 4/4 because the naming convention and note values are based on that time signature.
As seen in the above table, notes and rests are named after fractions. More accurately, the duration of notes and rests is named after fractions. The duration name is independent of the note name, the name identifying its pitch. And of course, rests have no pitch, only duration.
The duration names represent note and rest time value in relation to the whole note, and each, except for the whole note, is half the value of the preceding one. In 4/4 there are 4 beats per bar. A whole note gets 4 beats. A half note is 1/2 of the whole note, 2 beats (1/2×4). A quarter note is 1/4 of the whole note, 1 beat (1/4×4). An eighth note is 1/8 of the whole note, 1/2 of a beat (1/8×4). A sixteenth note is 1/16 of a whole note, 1/4 of a beat (1/16×4). A thirty-second note is 1/32 of the whole note, 1/8 of a beat (1/32×4).
The bottom number tells us how many notes of that type it takes to make one full 4/4 bar, 4 beats. There are 2 half notes (1/2), 4 quarter (1/4) notes, 8 eighth (1/8) notes, etc. (The following graphic only shows notes but the same fractional and quantity relationship applies to rests.)
The note and rest names don’t make sense in other time signature. There are not four 1/4 notes in 1 bar of 3/4, for example. There are explicitly only 3 – 3/4 says so. And there are 2 quarter notes in a bar of 2/4. That’s just the way it is. The important thing to remember is in time signatures with a “4” on the bottom, a half note/rest gets 2 beats, a quarter note/rest gets 1 beat, an eighth note/rest gets 1/2 a beat, a sixteenth note/rest gets 1/4 of a beat, and a thirty-second note/rest gets 1/8 of a beat. Refer to the table above.
Notes and rests in 4/4:
In 2/4. The example is slow. Milonga’s 2/4 is very much faster.
The other time signature tango uses sometimes is 4/8. There are 4 beats per bar and the eighth note gets 1 beat. Compare with 4/4.
Dotted Notes and Rests
In the first bar of the 3/4 example above there is a single dotted half note. Each note can have one or more dots to the right of the note head. One dot means to increase the note value by half. So, a dotted half note get 3 beats: 2 + (2 x 1/2) = 3. A dotted quarter note gets 1-1/2 beats: 1 + (1 x 1/2) = 1-1/2. A dotted eighth note gets 3/16ths of a beat: 1/8 + (1/8 x 1/2) = 3/16.
The habanera rhythm begins with a dotted eighth note, setting up the syncopation on the following sixteenth note.
There can be more than one dot. Two dots adds half the value of the first dot. A double dotted quarter notes gets 1-3/4 beats: 1 + 1/2 + (1/2×1/2) = 1-3/4. A double dotted eighth note gets 7/32 of a beat, that is, an 1/8 (4/32) plus 3/32: 1/8 + 3/16 + (3/16 x 1/2) = 7/32. Etc. It gets worse. There can be more dots… Fortunately there is a simpler way to indicate multi-dotted note values, by using ties. Tango might occasionally use double-dotted notes – off hand I don’t recall any examples – and I’m about 99.9% sure none have triple dotted notes.
A note is a sound or tone having two aspects:
1) The primary, auditory one, is pitch. Each note has a unique pitch, with a sound wave frequency measurable in hertz. In many parts of the world instruments are tuned to A at 440Hz.
2) The secondary, temporal one, is duration, called "time value" or "note value". When written or played each note has a specific duration, how long it lasts relative to the beat.
When pitch and duration are combined we get melodic shape and rhythm. Pitch creates melody and gives it direction, the melodic shape; duration provides the melodic rhythm.
The two numbers, one above the other, written near the beginning of the first staff line (or whenever it changes), specifying the number of beats in a measure and the type of note that gets one beat.
Beat is the underlying and regularly spaced pulse of the music, measured in beats per minute. There are a fixed number of beats in a bar, indicated by the time signature. Tango (2/4, 4/8, 4/4) has 2 or 4 beats per bar, vals (3/4) has 3 and milonga (2/4) has 2.
(There may be a sense of 4 beats even though the time signature is 2/4. Tango very often subdivides the 2/4 beat, doubling the count from 2 to 4, effectively using a 4/8 time signature. Some tango music is explicitly written in 4/8, most are in 2/4. See Tango Time Signatures and the Beat).
Milonga came before tango and its characteristic rhythm was, and is, the Cuban habanera. Early tango's rhythm was based on the habanera also. Soon other syncopated patterns dominated. The 1st variation, the "syncopa" is the most commonly heard syncopated rhythm in tango music. All three versions are used in milonga.
Habanera Variations describes the syncopation and relationship between these patterns.