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Thread: Harmonizing The Melody (Parallel Motion)

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    Harmonizing The Melody (Parallel Motion)

    I've been reading a theory book and it has a part which is explaining intervals when harmonizing the melody however i don't understand some of them.

    They are;


    Fourths: Fourths can be nice, but not in parallel. Parallel fourths are one of the major no-no rules of voice leading. However, since there is a fourth interval from the fifth of a triad to the root, a fourth can be just the right interval.

    Fifths : Fifths are also consonant intervals that work well. You don't want them in parallels either as they break the other major rule of voice leading. Plus, if you harmonize with straight parallel fiffths, it will sound like Gregorian chant.

  2. #2
    MMus, MA, PGCE JumpingJack's Avatar
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    Similar motion is when two parts move in the same direction (both up or both down).
    Whenever two parts move in similar motion and the intervals between them remain the same, this is also called Parallel Motion.

    When the intervals are perfect fifths (for example), this is commonly called "parallel fifths" or "consecutive fifths".

    Parallel fifths and parallel octaves are forbidden in classical part-writing.

    For example, imagine you have one part that goes from C to A, and a part below that with the same rhythm that goes from F to D.
    F to C is a perfect fifth, D to A is a perfect fifth. Therefore, this is an example of parallel fifths.

    Parallel fourths are usually tolerated providing they move by step (and the bass isn't involved).

    There's a bit more to it with various rules and exceptions, but that's it in a nutshell.

  3. #3
    Quote Originally Posted by zanshin777 View Post
    I've been reading a theory book and it has a part which is explaining intervals when harmonizing the melody however i don't understand some of them.

    They are;


    Fourths: Fourths can be nice, but not in parallel. Parallel fourths are one of the major no-no rules of voice leading. However, since there is a fourth interval from the fifth of a triad to the root, a fourth can be just the right interval.

    Fifths : Fifths are also consonant intervals that work well. You don't want them in parallels either as they break the other major rule of voice leading. Plus, if you harmonize with straight parallel fiffths, it will sound like Gregorian chant.
    The opening guitar melody lick in Wish You We're Here is "Parallel Harmony". I still love that intro to this day.
    That being said, the reason those rules are taught was because at some point in time it sounded better to follow those rules. I like to take "rules" and turn them into "strategies". Get into "Why" they worked and then use that strategy elsewhere.

    If a system is built on simultaneous notes then it makes sense to not want other numbers to have a 5. If they did it would make the Key weaker. Otherwise if you're caught up in the "these notes sound so good together" phase (which is just a great phase to be in) you have to understand that bad sounds can be "good" if the key is more Obvious.
    Last edited by Ken Valentino; 11-17-2013 at 10:52 AM.

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    Thank you very much guys, you are super cool.

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    Quote Originally Posted by JumpingJack View Post
    Similar motion is when two parts move in the same direction (both up or both down).
    Whenever two parts move in similar motion and the intervals between them remain the same, this is also called Parallel Motion.

    When the intervals are perfect fifths (for example), this is commonly called "parallel fifths" or "consecutive fifths".

    Parallel fifths and parallel octaves are forbidden in classical part-writing.

    For example, imagine you have one part that goes from C to A, and a part below that with the same rhythm that goes from F to D.
    F to C is a perfect fifth, D to A is a perfect fifth. Therefore, this is an example of parallel fifths.

    Parallel fourths are usually tolerated providing they move by step (and the bass isn't involved).

    There's a bit more to it with various rules and exceptions, but that's it in a nutshell.
    I guess JumpingJack made a mistake. Intervals are C between F and A between D are Perfect 4th are not Perfect 5th. Am i right?

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    Registered User JonR's Avatar
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    Quote Originally Posted by zanshin777 View Post
    I guess JumpingJack made a mistake. Intervals are C between F and A between D are Perfect 4th are not Perfect 5th. Am i right?
    He said F and D are below C and A - which makes them 5ths.

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    How?

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    Registered User JonR's Avatar
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    Quote Originally Posted by zanshin777 View Post
    How?
    F up to C is a 5th. D up to A is a 5th. Here's tab for what Jumping Jack was talking about:

    --------------------
    --------------------
    ---5----2------------ = "one part that goes from C to A"
    ---3----0----------- = "a part below that ... that goes from F to D"
    --------------------
    --------------------

    that's parallel 5ths.

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    From C to A, there are 4 whole steps and a half step, so it is Major 6th.
    From F to D, there are 4 whole steps and a half step, so it is Major 6th.

    in the other hand

    From C to F, there are 2 whole steps and a half step, so it is Perfect 4th.
    From A to D, there are 2 whole steps and a half step, so it is Perfect 4th.

    Since 4 + 5 = 9 (From The Rule Of Nine), reverse of the interval which is Perfect 4th is Perfect 5. However how do we understand that we choose parallel fifths here?
    Last edited by zanshin777; 12-04-2013 at 05:13 PM.

  10. #10
    Registered User JonR's Avatar
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    Quote Originally Posted by zanshin777 View Post
    From C to A, there are 4 whole steps and a half step, so it is Major 6th.
    From F to D, there are 4 whole steps and a half step, so it is Major 6th.
    Ah, but you're looking at the wrong intervals! Those are the melodic intervals, C moving to A, and F moving to D. (It could be a minor 3rd down as well as major 6th up.)
    Quote Originally Posted by zanshin777 View Post
    in the other hand

    From C to F, there are 2 whole steps and a half step, so it is Perfect 4th.
    From A to D, there are 2 whole steps and a half step, so it is Perfect 4th.

    I didn't understand how you've found Perfect 5th intervals.
    Because you've inverted the intervals Jumping Jack described. He quite clearly said that the F and D were below the C and A. (Read his post again.)

    From F up to C (or from C down to F), there are 3 whole steps and a half step, so it is Perfect 5th.

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    I'm surprised how i misunderstood. Sorry for thoughtfulness of me. However;

    Actually I have problem at defining the intervals both parallel and vertical.

    In parallel;

    While descending and ascending it is used different definitions for intervals.

    Example 1
    a) While ascending (getting high); from C to G is Perfect 5th. (why not perfect 4?)
    b) While descending (getting low); from C to G is Perfect 4th. (why not perfect 5?)

    Example 2
    a) While ascending (getting high); from C to E is Minor 6th. (why not Major 3rd?)
    b) While descending (getting low); from C to E is Major 3rd. (why not Minor 6th?)


    In Vertical (So in our situation)

    I don't know why we said it Perfect 5th though it could be Perfect 4th. (5 + 4 = 9)
    Last edited by zanshin777; 12-05-2013 at 03:17 PM. Reason: horizontal --> vertical, increasing --> ascending, decresing --> descending

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    bitter old fool Jed's Avatar
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    Quote Originally Posted by zanshin777 View Post
    Actually I have problem at defining the intervals both parallel and horizental.

    While decreasing and increasing it is used different definitions for intervals.
    Maybe I am not understanding your use of the language but the names we use to describe intervals might be easier to think of in terms of distance along a number line except we do not use negative numbers. We can count up or down (in pitch) as an absolute distance but without any sign.

    For example, counting from C (3rd space of the treble clef aka C5) up to G (1st space above the treble clef aka G5) is by convention called a perfect 5th. Counting from C (3rd space of the treble clef aka C5) down to G (2nd line of the treble clef aka G4) is by convention called a perfect 4th. The distances between these two sets of notes are not the same. The ascending from C pair is 3.5 steps while the descending from C pair is only 2.5 steps.

    Quote Originally Posted by zanshin777 View Post
    Example 1
    a) While increasing (getting high); from C to G is Perfect 5th. (why not perfect 4?)
    b) While decreasing (getting low); from C to G is Perfect 4th. (why not perfect 5?)
    See the description above

    Quote Originally Posted by zanshin777 View Post
    Example 2
    a) While increasing (getting high); from C to E is Minor 6th. (why not Major 3rd?)
    b) While decreasing (getting low); from C to E is Major 3rd. (why not Minor 6th?)
    From C4 up to E4 is a major 3rd (by definition)
    From C4 down to E3 is a minor 6th (by definition)

    The confusion maybe that you are mixing-up the definitions of intervals and scale degrees.
    Since E is the 3rd degree of the C major scale, many people will describe any E (in the context of a C tonality / frame of reference) as the major 3rd (scale degree assumed). Even if the E is on the bottom / lower in pitch than the C.

    Intervals are normally measured from bottom to top. C4 above E3 forms a minor 6th interval irrespective of the tonality. The easiest (or at least most accurate) way to describe an interval is from bottom to top in terms of the major scale of the lower note. So for C4/E3 (/ = over) we would think and count in E major where a C would be the minor 6th scale degree of the E major scale (C# being the major 6th). Likewise E4/C4 would be a major 3rd (counting up from the C)

    When speaking in terms of scale degrees the more important concept is how the note functions in a particular tonality rather than the intervals involved. In this case we are talking about pitch class (no octaves, all C's are the same function, etc) rather than any particular frequency / pitch / octave. So here we are not measuring intervals but scalar / harmonic relationships. There are no distances / intervals involved since we are not talking about specific frequencies / pitches. Rather when talking about scale degrees we are describing the thing that makes C/E and E/C sound similar in the key of C major.

    Pitch class is the phenomenon that describes the sameness between all notes of the same letter name irrespective of the octave.

    In terms of scale degrees, the major 3rd (E in C major) can be referred to as the (major) 3rd (of the tonality) irrespective of whether the actual note/pitch is higher or lower than some other note/pitch.

    When ascending: intervals distances and scale degrees are equal (same name). When descending: intervallic distances are the complimentary interval of the scale degree name. You may need to think your way through those last couple of sentences for this to make sense.

    cheers, Jed
    Last edited by Jed; 12-05-2013 at 02:54 AM.

  13. #13
    Registered User JonR's Avatar
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    Quote Originally Posted by zanshin777 View Post
    I'm surprised how i misunderstood. Sorry for thoughtfulness of me. However;

    Actually I have problem at defining the intervals both parallel and vertical.
    As Jed says, there seems to be a language issue here. In English, what I think you're referring to is "melodic" and "harmonic" intervals.
    Melodic intervals are those where one note follows another, in time. Start on one note, and go up - or down! - to another.
    Harmonic intervals are simultaneous, as in chords. These are always measured from bottom to top, although they can be "inverted". So a perfect 5th of C-G (C on the bottom) becomes a perfect 4th G-C when inverted (G on the bottom).
    But the distances are fixed. A perfect 5th is always 7 half-steps, although in melodic intervals you might count up (eg from C up to G) or down (G down to C).

    Harmonic intervals are the ones that matter in the case of the rules about parallel 5ths.
    Quote Originally Posted by zanshin777 View Post
    In parallel;

    While decreasing and increasing it is used different definitions for intervals.

    Example 1
    a) While increasing (getting high); from C to G is Perfect 5th. (why not perfect 4?)
    Because it's 5 notes: CDEFG. You're simply counting note letters, with the bottom one counting as "1st".
    The number of notes gives the type of interval; the number of half-steps determines its quality:
    C-G = perfect 5th
    C-G# = augmented 5th
    C-Gb = diminished 5th

    C-Ab is the same number of half-steps as C-G#, but is a "minor 6th", because we count 6 letters (CDEFGA).
    Quote Originally Posted by zanshin777 View Post
    b) While decreasing (getting low); from C to G is Perfect 4th. (why not perfect 5?)
    Because downward is only 4 letters: CBAG.
    That counts as a perfect 4th (harmonically or melodically, up or down), although we could (in some circumstances) view it as an inverted 5th.
    Eg, in a C major chord, CEGC, the top interval G-C is a perfect 4th, but C is the root, so we could say that - in the way it works - it's an inverted 5th.
    Quote Originally Posted by zanshin777 View Post
    Example 2
    a) While increasing (getting high); from C to E is Minor 6th. (why not Major 3rd?)
    It IS a major 3rd! C up to E is 3 letters (CDE), so it's a 3rd. And it's major because it's 4 half-steps (1 larger than minor).
    Quote Originally Posted by zanshin777 View Post
    b) While decreasing (getting low); from C to E is Major 3rd. (why not Minor 6th?)
    C down to E - or E up to C IS a minor 6th, because it's 6 letters - EFGABC - whichever way you count it.
    Invert a major 3rd and it becomes a minor 6th, and vice versa. But the name depends on the distance between the notes.
    Quote Originally Posted by zanshin777 View Post
    In Vertical (So in our situation)

    I don't know why we said it Perfect 5th though it could be Perfect 4th. (5 + 4 = 9)
    Code:
    C.D.EF.G.A.BC
    |______|____|
       5th   4th
    .
    C.D.EF.G.A.BC
    |____|______|
      4th  5th

    Doesn't matter which direction you count in, the number of notes is the same. But it does matter which way up the interval is (which note you count from).
    C-F = 4th, whether you count up from C or down from F.
    Likewise, F-C = 5th, whether you count up from F or down from C.

    Just to repeat: Jumping Jack's example was F below C - which is why it's a 5th (CBAGF, or FGABC).
    Last edited by JonR; 12-05-2013 at 12:38 PM.

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    Understood. Thank you very all. The explanation of the theory book which i've read had confused me. In conclusion, for defining the intervals' distances, there is no difference between descending and ascending. We should beware the octave degrees of notes and count the intervals. That's all.

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