Much of the confusion and misunderstanding is because when this subject is taught and explained, the teacher usually jumps from sine waves to music, where a musical note is thought of as a sine wave.
But it is better to think of a musical note as a set of sine waves. Each sine wave in the set has a frequency which is an integer multiple of the frequency of the longest sine wave. These frequencies are known as harmonics.
If we plot these frequencies on a logarithmic scale, they'll be evenly spaced.
Imagine a note as a comb, where each tooth represents the frequency of one of the sine waves. Now imagine a second comb where the teeth are spaced farther apart. Now imagine that you put one comb on top of the other so that the teeth line up. You'll see a nice pattern. This is the harmony of the combs.
But these combs aren't only in an abstract frequency space. The cochlea inside your ear maps each frequency to a specific physical location where your ear hairs are tickled, forming a comb-like pattern.
One way we can tell human voices apart is by the relative intensities of the harmonics. And the way we tell different vowel sounds apart is by the relative intensities of the harmonics. So our brains have lots of wiring for interpreting relative intensities of harmonics.
But it is better to think of a musical note as a set of sine waves. Each sine wave in the set has a frequency which is an integer multiple of the frequency of the longest sine wave. These frequencies are known as harmonics.
If we plot these frequencies on a logarithmic scale, they'll be evenly spaced.
https://en.wikipedia.org/wiki/File:Spectrogram_of_violin.png https://en.wikipedia.org/wiki/File:Human_voice_spectrogram.j...
Imagine a note as a comb, where each tooth represents the frequency of one of the sine waves. Now imagine a second comb where the teeth are spaced farther apart. Now imagine that you put one comb on top of the other so that the teeth line up. You'll see a nice pattern. This is the harmony of the combs.
But these combs aren't only in an abstract frequency space. The cochlea inside your ear maps each frequency to a specific physical location where your ear hairs are tickled, forming a comb-like pattern.https://en.wikipedia.org/wiki/File:Journey_of_Sound_to_the_B...
Consider this chord composed of the notes G4, C5, and E5, which some of you may know as C 2nd inversion or G⁶₄.
This chord will tickle your ears in many of the same places as the note C3. One way we can tell human voices apart is by the relative intensities of the harmonics. And the way we tell different vowel sounds apart is by the relative intensities of the harmonics. So our brains have lots of wiring for interpreting relative intensities of harmonics.https://auditoryneuroscience.com/sites/default/files/Fig1-16... (source: https://auditoryneuroscience.com/vocalizations-speech/forman...)
So when we hear this chord, our brains are likely using some of the same wiring they would use for a human voice singing the note C3.