Harmony is an integral part of music as we know it. In the dictionary, harmony is defined in this way:
The simultaneous combination of tones, especially when blended into chords pleasing to the ear; chordal structure, as distinguished from melody and rhythm.
In other words, whenever two tones are played or sung together, harmony results. Now note, this does not mean it sounds nice. Playing a C and a C# together is still harmony, even though the result is a minor second, one of the least nice-sounding intervals.
But before I get into detail about harmony, I want to talk a little bit about what makes a note a note.
You may think a not is simple, but it is not. As you probably know, higher sounds are caused by vaster vibrations, ans lower sounds are caused by slower vibrations. This is true, but there is more then that. Take an example, when you play a note on an oboe, it sounds distinctly different from the same not played on a cello. There is a reason for this.
A note is made up of not one frequency, but many. Lets say that you have an instrument playing an A above middle C, which vibrates at 440 Hz. The instrument will actually produce not only a 440 Hz sound, but also a little bit of a sound at 880 Hz, 1320 Hz, and so on. We perceive pitch as being whatever the lowest frequency is (440 Hz in this case). But the volume of the other harmonics (for that is what they are called) is what causes the note to sound like a certain instrument. We call this timbre.
Now that we know who notes are constructed, we can look at how notes work together to form chord and harmonies.
On the right is a chart showing the music intervals. If we consider our first note to be a C, a D flat would form an interval of a minor second. A D would form a major second and so on. A basic major chord (that is, a happy chord) is formed of a root note(in this case, C), a major third (E) and a fifth (G). The chord can be changed to a minor chord (that is, a sad chord) by changing the middle note from a major third (E) to a minor third (E flat). These notes can be combined in endless combination, but those two are the most commonly used ones.
Now, we cant just expect any two notes to sound nice together. Pythagoras figured it out. The intervals that are the most pleasing to the ear are the ones with frequencies that are ratios of small, whole numbers. The only intervals that the Greeks considered harmonious where the octave (ratio 1/2), perfect fifth (ratio 2/3) and a perfect fourth (ratio 3/4). So, in other words, an A has a frequency of 440. The frequency of a 5th above that is 660. This simplifies down to 2/3.
This is the reason that harmonies work the way they do. Harmonies can be combined in any which way. Some sound nice, some less so. But they are all harmonies.
Now, in modern music. The melody is whatever you hear predominately, and is usually sung by sopranos. For example you would know the melody of Twinkle, Twinkle, Little Star. If it where arranged for a chorus, everything else would be considered harmony.
The next post will be about rhythm. That thing that gets your foot tapping and your hands clapping.
Blog to you later.
This is part two about my series about how music works. You can read the other parts here: Part 1, Part 3