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Can someone please explain chords / music / frequency to me

  1. Jun 30, 2014 #1
    I understand octaves, like 100 hz, the first octave is 25, second, 50, and 100 the third octave.

    How can I relate all this to chords? I have been reading all this music lingo and cant correspond any of it to frequencies, and alot of the ideas from now today dont match up with the past etc.

    Also when we get in to consonance and dissonance I dont understand the frequency ratios. Also, is there a set idea of what ratios are dissonant and consonant?

    What is the difference between major, and minor chords?

    None of this makes sense to me in the relation of it all to frequency.
  2. jcsd
  3. Jun 30, 2014 #2
    The frequency given for a note is usually that of the fundamental or lowest frequency. A typical note includes harmonics, that is frequencies which are multiples of the fundamental, or the note sounds dull. For example the note A is 440Hz, the first octave is 880.

    Chords are made up by taking a note from the scale and adding third intervals to it. A major chord has a major third in it and a minor chord has a minor third. i.e C D E is a major triad and C D Eb is a minor triad. A basic chord has the root, a third, and a fifth. Add the 7th and you get a seventh chord etc.

    I can't teach this to you here you need to study it yourself.
  4. Jul 1, 2014 #3

    This is an interesting question to me as well.


    I don't think consonance and dissonance are fully explainable by frequency ratios alone.
    At some point I think this has to become subjective, because what we hear as consonance or dissonance, major or minor, depends on the characteristics of an individual's ear. Suppose the ear is treated as a resonating cavity, or the eardrum vibration as a bessel function, or whatever; the way the eardrum vibrates, and therefore the output signal, must depend on the physical characteristics of the ear. And since everyone's ears are slightly different, we must all hear things differently, however minutely.

    This leads to the conclusion that consonance and dissonance, major and minor, are meaningless outside of perception.

    This argument is very similar to the idea that the way I see the color red is not necessarily the way you see the color red. However, we have both learned to call it red. In reality, there is no "red" outside of our perception. That is not to say there are no frequencies of light which correspond to the color red. This is just to say that the color red only exists through perception, and similarly, consonance and dissonance only exist through perception.

    There might be standard frequency ratios for consonance, dissonance, major and minor, but consequently, they must be arbitrary. This is like trying to understand why 632.8 nm is red. It is arbitrary.

    Please correct me if I'm wrong.
    Last edited: Jul 1, 2014
  5. Jul 2, 2014 #4
    We have to be careful with our choices of words here as this is not entirely subjective though some value judgments are, and some are even cultural. Western scales are different from Eastern Scales and much of what is considered Western is tied in with the Piano. Half-steps and Whole Steps make up the repeating pattern that is on a piano keyboard but it does correspond to fairly precise frequencies, and sequences of those notes make up clearly defined scales and modes. People agree that Major chords have a "light" sound while Minor chords have a "dark, more brooding" quality. Similarly other chord structures are widely heard in the same way, triggering similar emotions in most humans.

    Humans agree, for example, that 2 tones just slightly apart beat on each other and this is measurable with metering so it is not subjective. Whether that beating is perceived as pleasant or unsettling, is. A person may dislike darker Minor chord based music while another finds them purging or bittersweet. Some people enjoy roller coasters while others won't ride them if paid. However just as Roller Coasters trigger certain neurochemicals in almost everyone, so does music. The subjective part is in the evaluation.

    This is an interesting read http://www.npr.org/2012/09/07/160766898/sound-a-major-emotional-driver-for-humans on parts of this subject.
  6. Jul 2, 2014 #5


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    The standard "intervals" are (approximately) ratios between low integer numbers, so they are a lot less arbitrary than, say, calling 632.8 nm "red." Major and minor are just part of the numbering system (bigger and smaller by half steps).

    How you "hear" consonance vs. dissonance is of course more subjective, but there are well established relationships which take into account not just the ratios of fundamental frequencies but also those of the harmonic (overtone) series.
  7. Jul 3, 2014 #6
    To illustrate the math of music, which is "just" a progression of related frequencies, and to see how these frequencies relate, here's a decent explanation.

    It's mostly empirical but does contain some Science if you'd like to read the full article from which this is quoted here -

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