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# L 10 The Tempered Scale, Cents PowerPoint PPT Presentation

L 10 The Tempered Scale, Cents. The Tempered Scale. We wish to make a chromatic scale- 13 tones including the octave- and we want all the intervals (ratios of adjacent notes to all be the same).

L 10 The Tempered Scale, Cents

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### The Tempered Scale

We wish to make a chromatic scale- 13 tones including the octave- and we want all the intervals (ratios of adjacent notes to all be the same).

We start with , let’s say, C. Of course the octave above is 2C. We want the ratio of the frequencies of all half steps e.g. C#/C = D/C# = Eb/D, etc. to be the same.Let’s pick that ratio to be 12√2= 21/12 = 1.05946.

is equal to:

### CT 2.4.5

is equal to:

C#/C = 2 1/12 or C# = 21/12CD/C# = 21/12 or D= (21/12 )C#= 21/12(21/12C) , orD= 22/12C….B=211/12C, and finally2C= 212/12C,which was the requirement.

### CT 2.4.5

In the twelve tone equal tempered system, suppose I want f2 to be one whole step above f1. What should I multiply f1 by to get f2?

### CT 2.4.5

In the twelve tone equal tempered system, suppose I want f2 to be two whole steps above f1. What should I multiply f1 by to get f2?

### CT 2.4.5

In the twelve tone equal tempered system, suppose I want f2 to be a perfect fifth above f1. What should I multiply f1 by to get f2?

### CT 2.4.5

In a just system, suppose I want f2 to be a perfect fourth below f1. What should I multiply f1 by to get f2?

### CT 2.4.5

Suppose we start at the note

A = 440 Hz and go up a fifth to E. What is the ratio of the frequencies of Ejust/Eequal tempered ?

### Sound clipsPythagorean, Just, Equal temperament

http://www.phy.mtu.edu/~suits/scales.html

http://www.pyxidium.u-net.com/Acoustics/MusicMaths/MusicMaths.html#pythag