I (31m) am new to music and trying to understand how the human ear hears a chord as a combination of strings.
To avoid ambiguity I’ll focus on the C chord of a 5 string banjo tuned to G.
The individual strings for a C chord are played with E,C,G,E,G(high)
How do G and E combine to sound like C? My initial thought is constructive wave interference but that seems like it would make an F note, not C.
Please help a newbie 🙂
In: 1
I’m not sure exactly what you’re hearing, but the wave interference works very differently from your mental picture. If I play a C, I don’t get a pure C sine wave, but instead I get a bunch of harmonics. If you looked at the note say on a computer, what you’d see is a lot of the C you played, but also a C an octave above, a G a fifth above that, a C 2 octaves up, then the E above that, the next G and so on. These are called overtones or harmonics, and how loud each one is goes a long way towards making instruments sound the way they do.
In terms of actual frequency, there’s the frequency f of the note you played (the fundamental), and integer multiples of that, so 2f, 3f, 4f and so on. Each octave is a factor of 2 in frequency, so going up one octave is 2f, two octaves if 4f etc., which is why 3f is a G if the fundamental is a C.
If you were to play two different notes, if they happen to share an overtone, then they can reinforce each other, and that overtone can sound like a note. Similarly, you can get interference like you said, which tends to produce the sum and difference of the two frequencies. A G is 3/2 of a C, and an E is 4/3 of a C. I don’t think you can combine those to get a C, so you’re probably hearing something else, but this is the basic idea of how frequencies combine.
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