Musical Scales
Pythagoras (1200 B.C.) found:
2 strings
| [1 twice the length of the other]
| octave
|
2 strings
| [length ratio 3/2]
| fifth
|
2 strings
| [length ratio 4/3]
| fourth
|
Going up a `fifth' each time he could get a whole musical scale.
One octave : from A --> A --> A
A B C D E F G A B C D E F
G A B C D E F G . . .
One fifth : C --> G --> D --> A --> ...
Eventually, one comes back to same note.
C . . . . ---> C
This is known of the "circle of fifths" (used in jazz)
Pythagorean Scale
NOT what we use today
Example:
220 Hz
|
=
| fundamental
|
440 Hz
| =
| 1 octave
|
660 Hz
| =
| a "fifth" above 440 Hz
|
660 Hz
| =
| 440 * 3/2
|
a fifth higher than 220 Hz: 220 * 3/2 = 330 Hz
a third higher than 220 Hz: 220 * 5/4 = 275 Hz
played at once => major chord
Musical Intervals
Interval |
frequency |
1. Pair of matching harmony |
Unison
| f1 ; f2 = f1
| f1 with f2
|
Octave
| f1 ; f2 = 2f1
| f2 with 2f1
|
Fifth
| f1 ; f2 = 3/2 f1
| 2f2 with 3f1
|
Fourth
| f1 ; f2 = 4/3 f1
| 3f2 with 4f1
|
Third (major)
| f1 ; f2 = 5/4 f1
| 4f2 with 5f1
|
Whole tone
| f1 ; f2 = 1.123 f1
| no match
|
Semitone
| f1 ; f2 = 1.0595 f1
| no match
|
Pythagorean Scale --> the third is off!
The Just Scale was created to fix this
- make a major chord above
- make a major chord below
- continue until all notes are found
Problem: has different sizes whole steps
Fix: Smooth out using the
Equal Tempered Scale
|