A more practical formulation of the question is "Why do we count by tones, instead of semitones?", but its meaning could be misinterpreted; the target of the question is actually on the concept of "1 tone" as a unit: "Why wasn't the smaller "interval leap", the actual semitone, taken as the unit and therefore called "tone" (or "one tone")?

We say there're 6 tones in an octave and then that the distance of the notes of major scale (for example) jump 1-1-1/2-1-1-1-1/2 tones.

Why wasn't what is known as "half tone" called a tone since the beginning, as a tone is not any unit whatsoever? Using the actual semitone as a unit, i.e. as a tone, we would have and octave with 12 tones and then simply show that the the "leaps" go 2-2-1-2-2-2-1 tones.

Is there a practical rationale for things not being this way and being the way they are? Are they this way merely for arbitrary or historical reasons?

  • How about the pentatonic scale? – Carl Witthoft Oct 3 '17 at 12:47

I believe it has to do with how humans have played music over the years. Just as audible language was invented before written language, so too was music. Theory evolved in order to write down what people were already playing. Your question is similar to asking "why don't we use the half inch as a base standard instead of the inch?". (Someone invented the metric system for just such a thing.)

One of the earliest scales is of course the major pentatonic scale. Starting on C, this goes C, D, E, G, A, C or 0, 1, 1, 1.5, 1, 1.5. No semitones to be found next to each other. People back then knew about semitones but they felt the pentatonic sounded better, was easier to play/sing, etc. In common usage of the time, scale degrees a semitone apart were rarer. Once the Major scale started to become the standard it still only contains two semitone intervals among 5 whole tones, making it the minority. The 4 and 7 are also often used to lead back to the tonic because of this dissonance.

Then, concerning the interval of a semitone (or minor second) itself, it is considered dissonant. The ratio between pitches is more complex than in a major second. It wants to resolve to something more stable.

Nowadays, music an a whole has evolved along with everyones ears, such that counting in semitones is very common. Dissonance is more accepted and semitones are in vogue. But musicians are slow to change when it comes to conventions like these.

In short, it's because whole tones were more commonly used than half tones. Splitting a tone in half occasionally is also easier than constantly having to double up, especially for larger intervals. Notation is also written to take this into account.

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    "I believe" is a statement of speculation and opinion, not fact. – jjmusicnotes Oct 6 '17 at 11:40
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    Well it is speculation, but she deserves a higher score as it is the only one answering my question. Not only that, but it does make a lot of sense! If no semitones were involved in scale steps, then it makes sense to call "one tone" to the not only most common but the minimal distance between two notes of a scale... And there was barely no need to talk about semitones except for 1.5 tones... Thanks @Tama! – Martin Oct 6 '17 at 20:56

Who says there are 6 tones to an octave? There are seven notes, and they are not evenly spaced. In equal temperament, considering them in units of semitones (which divide an octave into 12 equal intervals) makes some sense.

But equal temperament is a late comer to the game. And when you talk in terms of equal temperament, the unit for talking is semitones: a fourth is considered to be a distance of 5 semitones, not 2½ tones. A major second is two semitones, not "1 tone". At best, it is "a whole note apart".

Note intervals are named 1-based, semitone distances are counted 0-based.

This kind of distinction is done very rigidly, and yes, historical reasons play a large role. But once you leave the idea of equal temperament, semitones (or tones) as a unit stop making perfect sense.

And for better or worse, our precise notes may these days be equal-temperament, but the hearing of intervals in Western music isn't: you can walk in "thirds" through whole scales, and the resulting sound will be natural to our ears even though the result is having an irregular pattern of major and minor thirds (or 4 and 3 semitones of distance).

Playing such scales of thirds smoothly on an instrument organized by semitones (like a guitar or chromatic button accordion) rather than a note-based keyboard (like a piano) is actually taking a lot of practice.

So the "historical reasons" dividing an octave into non-equal notes rather than equal tones are actually still quite alive: dodecaphonic music has not taken the day.

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    Heh, how can two notes a major 2nd apart conclusively be called "a whole note apart"? Looks like a misspelling here, but an important one. – Dekkadeci Oct 3 '17 at 14:45
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    Thanks for trying to help user44521. Maybe the question is harder to answer or ask that I thought: "Who says there are 6 tones to an octave? " I studied solfege and harmony at the Conservatoire several years ago when I was a child, and the way we learnt, was that a major second was 1 tone, a major 3rd two tones, a fourth two tones and a half, a 5th 3 tones and a half, etc. It is more convenient to count half-tones/semitones, rather than tones, specially since applying it to guitar, although cognitively speaking, is quite understandable that many, or some, use tones as they are the "unit" . – Martin Oct 3 '17 at 23:36
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    I do count by semitones, since later on while studying modern harmony in the guitar. But anyway, if a tone is two semitones, and an octave is 12 semitones, then you can say it is 6 tones. No need to study logic for that. – Martin Oct 3 '17 at 23:38
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    But, that's not the question. I feared that misinterpretation and tried to warn about it. The question doesn't have anything to to with temperament (although yes, tones and semitones make sense in the equal temperament most played instruments use), or notes. Maybe my using of the word "interval" might have lead you to explain that "note intervals are named 1-based, semitone distances are counted 0-based." but I never referred to note or scale intervals, except for the distance in tones. I've been very reiterative about it. – Martin Oct 3 '17 at 23:38
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    The other things you say might have more or less sense, and I appreciate your contribution, but to clarify things I must say that they don't relate to my question (or at least it is not derived from your explanations). My question is just about the concept of choosing the name "1 tone" for that thing that results from dividing and octave into 6 intervals (yes, in equal temperament). And if someone is going to say that the octave is divided into 12 intervals, which doesn't matter for what is at stake, then the question is why choosing "1 tone" for 2 subdivisions? Why not 1 tone = 1 subdivision? – Martin Oct 3 '17 at 23:39

Taking a look at any diatonic instrument (and for better or worse, Western music is built on diatonic scales), the most common scale step (a major second) is two semitones. A major third is a distance of two major seconds, and four semitones. There is no two-semitone third (twice-diminuished is not really cutting it). So there is some point in calling the most common scale step a "tone" rather than "two tones", even thought the underlying grid is that of semitones.

It's not that uncommon: angles are often viewed/analysed in terms of "quadrants", with a quadrant being a quarter of a full revolution/circle. "In the third quadrant" will ring a louder bell with mathematicians than "in the second half-plane". Indeed, the latter can even trigger the question "which quadrants do you define your half-planes to be on?".

Now while the most common step in a scale covers a distance of two seminotes, you never place 6 such steps in a row in diatonic scales: a subdivision of an octave into 6 equal intervals is highly unnatural while a subdivision into 12 equal intervals is the basis of current scale construction.

So the principal unit is semitone (which, as a word, means "half tone"). If that offends your sense of mathematics: the principal standard international unit of mass is defined as the kilogram, 1kg, namely 1000 grams. According to etymology, the basic unit should be the gram.

If something as dignified as an international unit standard can use a multiple as a base unit, why shouldn't musicians be allowed to use a "semitone" as their base unit? It turns out that "1 cent" is actually 100th of a semitone, so the semitone as an anchor of musical reckoning is pretty firmly established, its name notwithstanding.

  • Talking about quadrants does make sense, but a circle is a very identifieable unit in itself. Again, I'm not talking about using the semitone as a unit per-se, but to the previous step of using "one tone" to the distance between C and D. Commonality is a criteria but not useful in itself, as it is proven but the fact that, as you said, most people now is counting by semitones. Being also the minimal distance, as Tama suggests clarifies things a lot. I've already answered to other things you say in the comments to the previous answer (I guess you are the same user). Thanks anyway though. – Martin Oct 6 '17 at 21:06

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