[steamer25]

The gist of music theory: It sounds interesting when sounds with simple frequency ratios are played at the same time. E.g., playing a 440 Hz tone at the same time and 660 Hz tone has a 2:3 ratio. Some combinations of frequencies, when played before or after other combos can establish an expectation and then either fulfill it or negate it. E.g., if you take the ratio above and then play 440 + 587, it'll sound like it's moving forward and that the second combo has 'arrived' as you might have expected. The 587 is derived by fixing the first note but inverting the relationship from 2:3 to 3:2 (and then doubling the frequency of the second so you don't have to move so far from 660).

Most everything beyond is attaching labels to the frequencies and combos. Just as we have names for frequencies of light (red, yellow, blue) and patterns (gradient, checkerboard) there are names for frequencies of sound (A, C#, E) and their combinations (major, minor). There are also more esoteric terms (chiaroscuro in painting, neapolitan flat 9 in music) for people who've spent so much time on a subject that the basics have become boring.

Oh, and there's also divisions of and patterns for time in music theory. E.g., "hold this note for twice as many milliseconds as the previous one".

There have been some good resources here on HN: https://hn.algolia.com/?query=music%20theory&sort=byPopulari...

[andrepd]

That's the gist of music theory as much as "radiation in the order of ~100nm excites your retina and you see colour" is the gist of photography or painting. x) It's the fundamental physical explanation, but there's a world of complexity and subtlety that eludes such a "first principles" explanation.

[steamer25]

I agree that to fully appreciate musical qualities, you have to play around with sound and that text alone won't suffice. On the other hand, your description of radiation hitting the retina might be a decent primer on color theory which has about as much to do with photography and painting as music theory has to do with playing an instrument. My goal was to demystify the jargon by showing that it has very tangible definitions which can be understood by even analytical audiences like HN (of which I include myself).

[steamer25]

> to fully appreciate musical qualities, you have to play around with sound

@jimbokun: It might be easier for your son to express what he's learning if you can catch while he's got e.g., a piano or guitar at hand. Humans have a hard time generating compound musical waveforms using just their vocal folds (though it can be done to a limited extent as in Mongolian throat singing). Explaining it while playing it will probably also help cement the concepts in his understanding ;) .

[jimbokun]

This is really easy to follow:

https://www.lightnote.co/

Already learned some things, thanks!

[HenryTheHorse]

Sorry, but you are way out of your league in trying to explain the "gist" of Music Theory in terms of frequencies. That's so not what Music Theory is about.

[rkangel]

This comment would be valuable if it provided some support to the assertion that the original author was wrong.

[Double_Cast]

The problem with the above explanation is that it starts at a lower level of abstraction than is warranted. Analogously, it explains MOSFET's rather than algorithms. The fundamental unit of Music Theory is the Interval (as in "frequency interval between notes"). A better explanation would have explained Intervals, how particular combinations of Intervals form various Scales, and how Scales influence Chord Progressions and Key Signatures.

There are 12 unique notes in an Octave (yes, octave means 8; ignore this for now). On the 13th note, the octave repeats itself (counting is 1-indexed). But of these 12 notes, only specific subsets are combined into specific scales.

The most popular scale is the Major Scale which follows the pattern "Tonic Major_2nd Major_3rd Perfect_4th Perfect_5th Major_6th Major_7th" (there exist other notations). The Major Scale imparts a generically-happy mood. But there's other scales, including: the Chromatic Scale; the Major Scale; 3 varieties of Minor Scales; 7 varieties of Diatonic Modes (including Major and Natural Minor); the Pentatonic Scales; etc. E.g. Smoke on the Water, Sunshine of your Love, and Fight for your Right (to Party) all sound similar because they use the Blues Scale.

Once you familiarize yourself with the intervals, scales, and their various notations (which is its own feat), you can jump into the meat & potatoes of Music Theory. Which mostly consists of analyzing Chord Progressions and Key Signatures in order to find commonalities in mood. Chord Progressions and Key Signatures determine a song's general mood. It's too complicated for me to summarize quickly. But it's where all the interesting stuff happens.

N.B. I've deliberately omitted various details for the sake of brevity. E.g. I could have mentioned Time Signatures, Rhythms, Tempo, Dynamics, etc.

[steamer25]

> The fundamental unit of Music Theory is the Interval (as in "frequency interval between notes"). A better explanation would have explained Intervals, how particular combinations of Intervals form

Guess what... A perfect fifth is a 3:2 ratio/interval of frequencies (+/- a small allowance for the historical/mechanical constraints that lead to well/equal tempering unless we're talking modern micro-tonalism in which case no adjustments are necessary). The inverse, 2:3, is a perfect fourth.

The example frequencies I gave correspond to concert-A, then E and D. I took a very simple/short path from intervals to harmonic function/progression to try to give a taste of the meat and potatoes before providing a link to additional sources.

I avoided music theory terms because that would've been a circular definition for any readers who had no understanding of even the basics.

In light of your post, I should've added a sentence or two about mood (major = happy, diminished = tense/scary) and compared that to how you can make a 'warm' picture using reds, oranges and yellows or a sombre picture with darker colors, etc.

[jimbokun]

"E.g. Smoke on the Water, Sunshine of your Love, and Fight for your Right (to Party) all sound similar because they use the Blues Scale."

Is there a good YouTube video introducing some of these concepts using popular songs?

[Double_Cast]

I didn't learn music through Youtube. So unfortunately, I'm not familiar with any videos that I would consider comprehensive or canonical. At best, I can share videos that highlight a particular pattern, or share examples of popular songs that I recognize as having a commonality. Which might give you a better feel for what music theory is.

Another thing to keep in mind is that musical patterns accrete into genres. And there's a wide variety of genres. So it's difficult for any single video to cover everything in detail. I think it's more common for videos to cover the patterns of a particular genre. E.g. if you're interested in Blues, consider searching for videos about Blues.

-----

https://www.youtube.com/watch?v=xm4LO22-cyY I remember the above Vox video highlights a unique chord which sounds "melty" and is often used in holiday music. The chord is known as a "minor_7th, diminished_5th" aka "m7d5".

https://www.youtube.com/watch?v=5pidokakU4I This video is about the infamous "4-chord pop progression". It's ubiquitous on the radio. Elitists and connoisseurs tend to look down on it for appealing to casuals. The progression is "I V vi IV" (capital denotes major chords, lowercase denotes minor chords).

https://www.youtube.com/watch?v=kfjXp4KTTY8 When I think of the "12-Bar Blues (Chord Progression)", I think of Stevie Ray Vaughn's "Pride and Joy". But there's tons of educational videos on this. It's very popular in not only Blues, but Rock & Roll. It's "I I I I; IV IV I I; V IV I I". But things get interesting here because musicians often substitue "jazzy" chords like Dominant_7th's (aka V^7). For bonus points, look up "tritone" (N.B. Rock is truly the devil's music).

https://www.youtube.com/watch?v=dISEg1ydQoM I'm not actually sure what song I'm thinking of, but there's a particular trope often used in Hollywood films to denote a bullfight. It's based off the Phrygian Mode, which tends to sound very "spanish-y". In lieu, I've linked the the first bullfight track I found.

https://www.youtube.com/watch?v=X4fa44_sq2E A genre I'm particularly fond of is House. Which is often characterized by its "Four on the Floor" drum beat. It's very simple, just continuous quarternotes of kicks. The rhythm is sometimes denoted "1 2 3 4" (where the structure of a single bar is "1 e & a 2 e & a 3 e & a 4 e & a"). The above video is Daft Punk's "Superheros".

And then there's Jazz. Which is hard to explain, because it's the genre where anything goes. And besides jazz, there's lots of other techniques and obscure genres that I can't possibly cover in a single post.

---------------

In any case, I'd suggest looking up a particular genre you like and studying it. If you're a musician, learn scales. 90% of pop music these days uses either Major or Natural Minor. But you can really expand your horizons by learning other scales. It's boring, but it builds a strong foundation. Like how a basketball player will run laps rather than shoot freethrows all day.

[khedoros1]

OK. What is music theory about? The explanation using frequencies, ratios, etc matched my understanding of the underlying physics and their effects on human perception.

[HenryTheHorse]

"Music Theory" is a very specific term that's used in music studies.

It is mostly a descriptive theory in that it studies musical patterns (rhythm, melody, harmony, intervals, scales, modes, chords and chord progressions) but it can also be prescriptive (for e.g. - don't use certain note intervals in a guitar solo if you are using certain chords in your song)

None of this has anything to do with Physics. Music Theory is completely abstracted from the physical world.

[Double_Cast]

Frequencies : Music Theory :: Logic Gates : Computer Science.

See my other comment.

[khedoros1]

Well...logic gates are (at a slightly abstracted level) just the reification of some of the logical concepts in computer science. Those concepts could be arrived at by observing the behavior of the gates.

Similarly, it seems like studying the frequencies and their relationships illuminates at least a portion of what music theory covers.

[opinionator1]

Wow, that's really not what music theory is at all. This kind of eggheaded simpletonism is grossly offensive and embarrasses the HN community, not to mention engineers in general. Please, the world outside of STEM is not reducible to a few hand-wavy sentences about physics.

[steamer25]

It's more about the ratios than the example frequencies I provided. That's more apparent if you play an instrument with an exposed string and a finger-board but still true if it's hidden under e.g., the hood of a piano. The definition of consonance versus dissonance is basically whether or not the ratio is simple. The overtone/undertone series from which the various scales are derived is also one only one logical step away. One step past that gets you to diatonic harmony which leads to harmonic progression/retrogression which makes up the bulk of my theory text book and the real gist that I was getting at.

If you can provide a better overview or point out how it's anything more than a bunch of terms/shorthand for sonic patterns, I'd love to be informed.