Chords & Discords
A chord is three or more notes sounded together, but for our purposes we'll say its two or more, just for the sake of this exploration. A discord is an inharmonious combination of musical tones sounded together.
The question is: what makes the difference between a chord and a discord? You may think there's an obvious answer ie "Chords sound nice, discords don't". But, think about it, "sounds nice" is in the ear of the beholder - ie completely subjective. And if we look back into attitudes towards harmony in times past, we find that people were less used to more complex "jazzy" harmonies and found them less pleasant than people generally do today. So perhaps there's no definite difference between a chord and a discord at all(?) Let's see if you agree...
Ignoring unison (ie two or more simultaneous soundings of the same note), the most perfect harmony is the octave, which arguably is not a harmony since it is the same note at a different pitch. We call all notes that are octaves of each other by the same name, and their notes vibrate at twice or half the frequency of others (or quarter or four times etc). Try it on your Harmonic Table - play all the light blue notes. You'll hear they all sound good together. No question, its harmonious.
Consider a vibrating string or column of air as in a traditional instrument. The main sound the string makes comes from its whole length vibrating. But there are other overtones present in the sound. The octave comes from both halves of the string vibrating with a node half way along the length of the string. Each half vibrates at twice the speed (or frequency) as the whole string.
So, what's the next most harmonious combination of notes? The next overtone of a vibrating string is a perfect Fifth, which is produced by the string vibrating in thirds. Obviously thirds is a nice mathematical relationship and its not surprising the harmonic equivalent sounds good. Find a Fifth for any note immediately above your starting note on the Harmonic Table. This two note chord sounds good. I don't think anyone would disagree. The upper note makes three vibrations in the same amount of time that the lower note makes two. Try it all over the key surface - that is any note with the one above. So far, so good.
Perhaps we've all heard how bad music can sound when the instruments (or voice) are out of tune. One can ask: why does it sound so bad? Think about strings again. If the two vibrate at the same frequency or pitch, of course they'll sound good together. But if one is just a little off, it sounds bad. [ If the two notes are just a very very very little off, as in a twelve string guitar, rather than sounding bad it can just "thicken" the sound - yet more than just this little produces a dissonant or un-harmonious sound. ]
So if one note is double or triple the frequency of another it'll sound alright, but if the frequencies are close it probably will not.
Check it out
To check out some chords and discords let's use this diagram. You've played a nice-sounding two note chord. (Notes 1 and 5). Now for a "discord" play notes 7 & 8. Not discordant enough? Play notes 1 & 2 and the C# in between them - all three together. Now that's three very close notes, and many people would say its a discord ie doesn't sound harmonious or particularly nice.
So, is it that certain notes just don't sound good together? Eg note 7 & 8 (B & C) together are not particularly harmonious. Now what happens if you play note 1 (C) and note 7 (B) together? I think you'll find that 1 & 7 together don't sound so bad, although they are also B & C. So its not just the note names that makes the difference. Perhaps we can say "the more spread apart notes are, the less likely they are to make a discord".
One last thing to try. Play notes 1 & 2 together. Ask yourself: is that a chord or a discord? I don't know. You tell me.
You've played 1 & 2 together. Now try 1 & 3. Fairly harmonious. Same for 1 & 4, and now we're getting back to further apart notes again.
The Harmonic Table is arranged such that the next door notes are not particularly close together in pitch. That means next door notes are harmonious. Try any two adjacent notes. Also, playing three notes in a bunch by pressing at the corner between all three also sounds harmonious.
Now let's try adding more notes into the chords. Try 1,3,5,7. Nowhere in that are there any close notes (like 7 & 8). The same applies for 2,4,6 and 4,6,8 and 2,4,6,8. Try it. However although 3 & 4 don't touch, like 7 & 8, they are close in pitch. Try playing 2,3,4 or 1,3,4. Not particularly sweet I think you'll agree.
Now check out playing various chords with more and more notes. You'll probably find those that sound less harmonious are those in which there are one or more close-in-pitch notes (like 3 & 4 or 7 & 8). Of course the more notes you sound together, (especially when close in pitch) the more likely some will clash. Try spreading the notes out, and you'll probably find they clash less (like the B and C which clash when close but less when further apart).
So who's to say what's a chord and what's a discord? ...the answer is YOU (or nobody). And who's to say that you should not use "discords" in your music. Should your music contain only the most harmonious sounds? I think it would be pretty boring if the only intervals were octaves and fifths. Some of the best music has plenty of dissonant or inharmonious sounds. They can be used to great effect to create tension and atmosphere, as in some film music.
Example instances of many of the most widely used chords can be found using our chord calculator.
- Octaves and fifths and notes whose frequencies are multiples of each other sound harmonious together.
- Generally, unison (same note) is considered the most consonant interval while the near unison is considered the most dissonant.
- Notes which are further apart from each other are less likely to clash.
- The more notes sounding together and the closer in pitch, the more likely you are to produce a discord.
- What is considered harmonious is a matter of personal taste. What constitutes a discord is subjective.
- There's no reason to make all your music sound harmonious or otherwise, and the interplay between more or less harmonious is a useful aspect of your composition.
- The Harmonic Table places notes which sound harmonious together next to each other, and places notes closest in pitch (like 7 & 8) apart.
For more see Wikipedia on Consonance and dissonance.
Disclaimer: I could be wrong ... always consult a professional.