Assignment 5
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Scales and Tuning

Due whenever

  1. Compute the ratio and the value in cents corresponding to each of the following:

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    The Pythagorean comma is the tiny interval by which twelve just perfect fifths differ
    from seven octaves.

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    The Syntonic comma, also called simply the comma, is the tiny interval by which the just
    major third differs from four perfect fifths less two octaves.

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    The Septimal comma is the tiny interval by which the septimal minor seventh (having a
    ratio 7:4) differs from the Pythagorean minor seventh.
     

  2. Assuming 12-tone equal temperament (12-TET), find a set whose interval vector is <2,2,4,2,2,3>.
     

  3. Consider the 17-TET scale, whose notes are numbered 0-16.  Consider also the 12-TET scale,
    whose notes are labelled C, C#, D, D#, etc.  We can embed 12-TET into 17-TET by assigning
    C in 12-TET to 0 in 17-TET, and then considering a fifth to be the ratio 10/17, and assigning
    each of the other notes in a "circle of fifths" manner.

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    Complete this embedding -- i.e. give the other note assignments.

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    How many non-trivial (i.e. non-zero) interval classes are in 17-TET?

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    Write the above embedding as a (singly) generated set, if possible.

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    What is the interval vector of the embedded scale?

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    Which of the following properties does this embedded scale have:
    G, WF, MP, DE, ME, DP, DT.