1. The information line: is the first line of the song under the song's title and author's name. This line shows three or less parts: Tempo, Time Signature, and Key Signature (some times tempo and key signature are not presented)
2. Tempo: In musical terminology, tempo (Italian for time, movement) is the speed or pace of a given piece/song.
It is a crucial element of composition, as it can affect the mood and difficulty of a piece. In modern music, beside using "tempo words" such as Andante, Moderato, etc, Tempo is usually indicated in beats per minute (BPM) = a certain number of these beats must be played per minute. The greater the tempo, the larger the number of beats that must be played in a minute is, and, therefore, the faster a piece must be played. Mathematical tempo markings of this kind became increasingly popular during the first half of the 19th century, after the metronome had been invented by Johann Nepomuk Mälzel, although early metronoms were somewhat inconsistent (Wikipedia). Examples: (beat = 100) --- > 100 beats per minute. (beat = 90) ---- > play 90 beats per minute (beat = 60 - 70) or (Allegro agitato) or (Andante Moderato) or (Larghissimo)
3. Time Signature (n/d): to specify how many beats are in each measure (for simple cases, numerator is 2 or 3 or 4) and what note value constitutes one beat (4/denominator).
A measure is a part lies between two bar lines ( | ). Examples 3/4 => "1" is a beat (since 4/4=1) and there are 3 beats in each measure. Example: | 6c1 6d1 6e1 | 6f2 1 | 4/4 => "1" is a beat and there are 4 beats in each measure. 2/4 => "1" is a beat and there are 2 beats in each measure. 2/2 => "2" is a beat (since 4/2 =2 ) and there are two beats in each measure. Example: | 6g2 7d2 |
For complex cases, numerator is not 2 or 3 or 4, then divide the numerator by 3 to find number of beats in each measure
Ex: 6/8 => There are 2 beats in each measure (since 6/3=2) and "1.5" is a beat (beacuse 4/8 = 0.5 and 0.5 *3 = 1.5) 9/8 => There are 3 beats in each measure and "1.5" is a beat. 6/4 => There are 2 beats in each measure and "3" is a beat.
How about numerator is 5 or 7 or 11....(cannot divide by 3)? then split it to simpler cases:
5/4 = 3/4 + 2/4 or 2/4 + 3/4 7/8 = 3/8 + 4/8 or 4/8 + 3/8 or 6/8 + 1/8 or 1/8 + 6/8 ...
4. Key Signature: Key signature is the third part in the information line at the beginning of a song. It looks like this:
Plus: [+f, c, g, d, a, e, b ] Minus: [-b, e, a, d, g, c, f ]
It is a series of plus (+) or sharp (#) notes or minus (-) or flat (b) notes placed in the squared bracket (in order of circle of fifth) designating notes that are to be consistently played ONE SEMITONE (half-step) higher or lower than the equivalent natural notes unless otherwise altered with an accidental. In short, key signature tells you which notes are turned black. For example: [+f, c ] or [- b, e, a] means play notes f, c, b, e, and a with black keys next to them (on the right for +, left for - ) Key Signature also lets us know which chords are the major chord or minor chord of the song.