2.b) Beat, Bar, Time Signatures and Tempo

2.b.1) Beat(s)

2. With beats, clear and stable rhythms can be articulately presented (performed) in a music.

Bar is a graphic musical notation inform of vertical line(s) known as bar line(s) that indicates several regular segments (groups) of beats along the staves.
The small number of regular beats (usually less than 16 beats) in a group of bar segments (within the bar lines) provides articulate (fluent) beat counting and clear metric structure: regular reference points of musical phrasing and sections.
The number of beats in each bar is specified by a time signature, which usually notated at the beginning of a musical section on the music score.
There are four types of bar line:
1. Bar line (indicates normal divison of beats).
2. Double barline (indicates the end section(s) of music and followed with a new section of music with either change of tempo, style, time signature and key signature).
3. Start and end repeat bar lines (indicates one time repeat on a section of bar(s).
4. Final bar line (indicates the end of a music).

Time signature is a musical notation symbol indicates the type of beat value for the beat counting and the number of beats in a bar.
A time signature (or meter for American US terminology) is written at the very first bar of a music section and after a double bar line (see Figure 2.b.2.1).
With a time signature, clear beat count can be conducted to unify rhythms playing from multiple parts of rhythmic lines vertically.
- https://www.youtube.com/watch?v=DdvHUJ88tao
Time signature consists of two types:
- Simple time signatures: a single regular beat equal to one regular beat count (produce strict-cut pulse)
- Compound time signatures: a regular group of three beats equal to one regular beat count (produce swing-lifting pulse)
Time signature also can be categorised according to the number of beat count in a bar:
- Duple: two beat count in a bar.
- Triple: three beat count in a bar.
- Quadruple: four beat count in a bar.

The speed of beats in a music indicated by a tempo marking:
- [x] [y] beats per minute (bpm), whereby [X] is the number of beats and [y] is the beat note value. Example 60 crotchet beats per minute (♩ = 60 bpm).
- Traditionally, the tempo marking can be “expressed” usually in Italian terms (German and French terms also can be used). Example, moderato (at a moderate tempo, usually between ♩ = 108 to 120 bpm).
To increase or decrease the tempo, we can either:
- a) changing the number of [x] beats. Example, reducing the number of [x] beats per minute will reduce the tempo of the beats (music) proportionally.
- b) changing the note value of [x] beats. Example, by replacing the original beats note value of a music at crotchet = 60 bpm into minim = 60 bpm, the music will be performed at half slower from its original tempo.
Tempo can be modulated (changed) within each musical section or a few bars such as using tempo marking of accelerando (Italian terms) or accel. literally means gradually faster or ritardando (Italian terms) or rit. literally means gradually slower and to continue the music with its previous or original tempo, we can add a tempo marking of a tempo (Italian terms) literally means normal tempo.

4. With tempo, a time duration of a music can be determined by using:

Example 1: a piece of music Z has 4 crotchet beats in a bar with a total of 32 bars and a tempo ♩ = 60 bpm.
- Duration music Z = [4 crotchet beats in a bar x 32 total bars x 60 seconds] / 60 crotchet bpm
- Duration music Z = 128 seconds = 2 minutes and 8 seconds.
Example 2: a piece of music W has 2 minim beats in a bar with a total of 32 bars and a tempo minim = 60 bpm.
- Duration music W = [2 minim beats in a bar x 32 total bars x 60 seconds] / 30 minim bpm
- Duration music W = 128 seconds = 2 minutes and 8 seconds.