I just read Physics and Music: The Science of Musical Sound Book by Donald H. White and Harvey Elliott White and the book explains that consonant frequencies — those sounding "good" when played together — are those whose ratio are simple (like 1/2, 2/3, ..., see Pythagorean ratio).

However, the book doesn't give a precise answer on why it is like that, and it seems there was no consensus at the time of writing (1980).

What is the current consensus ? Is the explanation "It's because those frequencies are more likely to appear together in nature, as partials of the sound emitted by a vibrating material" correct or is it more complicated ?

  • "why it is like that" - do you mean, which biological organs/cells are part of the chain of events that leads to sensing or feeling "consonance" or whatever the phenomenon is called? or is this about evolutionary biology or other explanations for how life and man came to be, speculating on what benefit an organism might have had from getting feelings of consonance from certain frequencies? AFAIK, music practice utilizes whatever phenomena there are for artistic or entertainment purposes, and music theory describes the phenomena like, such and such frequency ratios feel like so and so. Commented May 3, 2021 at 10:38
  • Well I mean most people will be able to say when two notes are dissonant. Even if they didn't study music. So my question is, where does this ability to distinguish those consonant / dissonant notes come from. Does it come from evolution / natural selection ? Is it acquired when growing ? Both ? And what are the environmental factors that drive this (whether it's natural or learnt) ?
    – Weier
    Commented May 3, 2021 at 12:28

1 Answer 1


It isn't really a matter of "it's more complicated than that" or a "consensus."

The simple fact is there is no objective measure or cut off point for what is consonant or dissonant.

It's a matter of culture, school of music theory thinking, and harmonic style.

IMO the best example is the perfect fourth. It was sung in parallel in the dark ages, treated as a dissonance in contrapuntal styles, considered a consonance by some in some harmonic settings, in acoustics as ratio 4:3 it is "simple" enough to surely be a "consonance." In other words, there are many standards, there isn't one objective measure.

In the postmodern world you can maintain multiple "conflicting" views. Even is a single piece of music you could have sections where perfect fourths are given a contrapuntal treatment and treated like dissonant suspensions and then other sections of quartal harmony where they are treated like consonances. In terms of taste and perceptions the musician making such music accepts and appreciates both treatments. There isn't a "consensus" to choose one or the other. Intellectually, the musician knows technically how to handle things in both styles. When you do it one way in a certain style it doesn't make the other way wrong.

You can say similar things about other intervals that are traditionally considered dissonant like seconds, seventh, tritones, etc. With the right stylistic treatment they are "pleasing" or even more generically "good" - words commonly used to describe consonance.

Acoustically you can only speak of a spectrum of consonance and dissonance with 1:1 most consonant and more complex ratios being gradually less consonance more dissonant. (Mathematically I think you must say that dissonance is infinite, there is no most dissonant ratio, because you can keep making infinitely smaller fractions.) There is no objective way to draw a line in that infinite spectrum of consonant and dissonant. In actual musical practice that line is draw, but it is draw subjectively and with no consensus among many styles and schools of thought.

  • There certainly is a cultural influence, as you say, but I just found two sources indicating that the preference for consonant sounds may also exist for other species, see pnas.org/content/111/46/16616 and smithsonianmag.com/science-nature/…
    – Weier
    Commented May 3, 2021 at 14:20
  • That's a huge leap from those articles to harmony! Where are the articles about hermit thrush preferences for singing in harmony? We don't need to bring in the discussion of hermit thrushes, because the point of the articles is in reference to the overtone series, and the overtones series simply does not explain harmony. That point is pretty well beaten to death in music theory. Commented May 3, 2021 at 14:42
  • In the first links, it says "Our findings add to a small but growing body of research showing that a preference for small-integer ratio intervals is not unique to humans and are thus particularly relevant to the ongoing nature/nurture debate about whether musical predispositions such as the preference for consonant intervals are biologically or culturally driven." That seems totally relevant to my initial question about Pythagorean ratio, don't you think ?
    – Weier
    Commented May 3, 2021 at 18:39
  • There isn't an onging debate. The overtone series simply doesn't determine musical art. Academics do get things wrong sometimes, especially when they venture outside their actual expertise. The point about the birdsongs, etc. is just coincidence. I says more about people than the animals. We find those birdsongs interesting, because of a coincidental similarity to an aspect of human taste. The vast majority of natural sounds have nothing in common with the overtone series. Commented May 3, 2021 at 19:05
  • And the overtone series isn't a natural phenomenon. It's a characteristic of human made musical instruments. Commented May 3, 2021 at 19:06

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