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Show HN: Teoria.js - Music theory for JavaScript

77 points by saebekassebil 14y ago

deleted 14y ago
[deleted]
lowboy 14y ago
This isn't really what I expected when I saw "music theory". It would be more aptly titled something like "frequency visualizer of chords".
- arielserafini 14y ago
  Same here, not what I expected. Looks great, though!
- simmons 14y ago
  I took a quick look at the Javascript code on saebekassebil's GitHub, and it does seem to be the start of some sort of music theory library. The waveform visualizer demo just doesn't seem to be very revealing of what the library is about.
  - jtheory 14y ago
    The actual library does look like it does quite a bit more than waveforms -- it's mostly focused on relationships of notes (in scales, intervals, etc.), and perhaps only secondarily on frequencies. Interesting! I have done similar work in Java -- built a library exploring note relationships, and also handling basic notation display -- but one of these days I'm going to need to migrate everything from Java applets (I know, I know) to HTML5, so I'm collecting these kinds of resources that may prove useful.... The name selection isn't great, BTW... there's been a well-known music theory website at teoria.com for more than a decade. It's a generic term (just "theory" in Spanish), so this likely isn't a legal issue, but that's going to make it quite hard to find this in Google.
- deleted 14y ago
  [deleted]
- submersible 14y ago
  Teoria.js does have a music theory api for working with notes, chords and intervals. I'm actually using it for a site I'm working on: http://groktar.com/?m=kTD4PzaNwv http://groktar.com/?m=kTD4PzaNwv (shameless plug)
arielserafini 14y ago
Okay, this link doesn't look like it does this justice. I found the Github page to be much better: https://github.com/saebekassebil/teoria https://github.com/saebekassebil/teoria
simmons 14y ago
Neat! I've been reading up and playing around with this stuff the past few weeks, from both the waveform synthesis side and the music theory side. I don't think I've quite wrapped my head around the basic concepts yet. (i.e.: Why have non-chromatic scales that skip semitones? Why do some sets of notes sound good and not others? What parts of sound quality derive from innate psychoacoustics, and what parts are my bias from growing up in the Western world?) I'll definitely be taking a closer look at saebekassebil's Javascript code, which seems to be an attempt to organize these concepts. It's strange how once you get interested in a topic, you start seeing stuff about it everywhere. First the Clojure-based Overtone project, and now this...
- Devlin_Donnelly 14y ago
  As to why some sets of notes sound good or harmonious and others sound "bad" or dissonant, we find that frequencies with the simplest mathematical ratios tend to sound the most harmonious, while frequencies with more complex ratios sound more dissonant. So for example the simplest ratio 2:1 corresponds to an octave interval. Notes which are an octave apart sound so similar that we describe them with same letter. So concert A is 440Hz and the "A" note one octave higher is 880Hz. The next simplest ratio, 3:2 corresponds to the interval known as a perfect fifth. So given the example of concert A at 440Hz again, one perfect fifth above concert A is the note E which has a frequency of 660Hz as (440 * 3) / 2 = 660. We find the simplest ratios of frequency intervals present in music from cultures the world over. The traditional classical Western twelve-note scale consists of the 12 simplest frequency ratios. In some Eastern music we hear a pentatonic or five note scale, which consists of the five simplest frequency ratios. So this aspect of music we can attribute to innate psycho-acoustics or even physics rather than cultural bias.
  - jtheory 14y ago
    > So this aspect of music we can attribute to innate psycho-acoustics or even physics rather than cultural bias. It's inextricable from cultural bias, though the physics obviously plays some role. The cultural bias comes into play more strongly around the question of how much dissonance is "good" vs. "bad", and how the more dissonant bits should interplay with the more consonant bits of music. Certainly, "more consonant = better" isn't true in any culture I can think of.... Imagine an orchestra that tunes up, then they all play the note A in various octaves for 3 hours. Possibly also worth mentioning that this isn't quite correct: > The traditional classical Western twelve-note scale consists of the 12 simplest frequency ratios You're thinking of the major scale, maybe? The ratios for a tritone, major 7th, etc. are more complex (and not the first 12 simplest...) and if you try to actually come up with ratios for an even-tempered scale you're really in trouble.
afandian 14y ago
On a similar note to this, I had great fun writing the keyboard and stave search input for for http://www.folktunefinder.com http://www.folktunefinder.com in JavaScript (you'll find keyboard-xxx.js file in there if you look). (For bonus points the search engine is written in Go).
acarabott 14y ago
I made a quick fork to add audio to this using the Web Audio API (webkit only, tested on Chrome and Safari). http://acarabott.github.com/teoria/ http://acarabott.github.com/teoria/
- SoftwareMaven 14y ago
  Had fun figuring out where mine and my wife's hearing fell off. Now I know where to put it when I want my kids to bugger off. :)
  - cosmikduster 14y ago
    http://onlinetonegenerator.com/ http://onlinetonegenerator.com/ has a nice hearing test using the audio API of Firefox.
robmiller 14y ago
As a once undergrad music student now working in acoustics, thanks for creating this. Something like this has been on my list of things to program, especially with libraries out there like D3.js. Good luck!
DanWaterworth 14y ago
I've never considered the waveform of a chord before, is the reason that some intervals sound harmonious because the period of their combined waves is short?
- spiralganglion 14y ago
  Yes, exactly.

77 points by saebekassebil 14y ago

deleted 14y ago

[deleted]

This isn't really what I expected when I saw "music theory". It would be more aptly titled something like "frequency visualizer of chords".

arielserafini 14y ago
Same here, not what I expected. Looks great, though!
simmons 14y ago
I took a quick look at the Javascript code on saebekassebil's GitHub, and it does seem to be the start of some sort of music theory library. The waveform visualizer demo just doesn't seem to be very revealing of what the library is about.
- jtheory 14y ago
  The actual library does look like it does quite a bit more than waveforms -- it's mostly focused on relationships of notes (in scales, intervals, etc.), and perhaps only secondarily on frequencies. Interesting! I have done similar work in Java -- built a library exploring note relationships, and also handling basic notation display -- but one of these days I'm going to need to migrate everything from Java applets (I know, I know) to HTML5, so I'm collecting these kinds of resources that may prove useful.... The name selection isn't great, BTW... there's been a well-known music theory website at teoria.com for more than a decade. It's a generic term (just "theory" in Spanish), so this likely isn't a legal issue, but that's going to make it quite hard to find this in Google.
deleted 14y ago
[deleted]
submersible 14y ago
Teoria.js does have a music theory api for working with notes, chords and intervals. I'm actually using it for a site I'm working on: http://groktar.com/?m=kTD4PzaNwv http://groktar.com/?m=kTD4PzaNwv (shameless plug)

arielserafini 14y ago

Okay, this link doesn't look like it does this justice. I found the Github page to be much better: https://github.com/saebekassebil/teoria https://github.com/saebekassebil/teoria

simmons 14y ago

Neat! I've been reading up and playing around with this stuff the past few weeks, from both the waveform synthesis side and the music theory side. I don't think I've quite wrapped my head around the basic concepts yet. (i.e.: Why have non-chromatic scales that skip semitones? Why do some sets of notes sound good and not others? What parts of sound quality derive from innate psychoacoustics, and what parts are my bias from growing up in the Western world?) I'll definitely be taking a closer look at saebekassebil's Javascript code, which seems to be an attempt to organize these concepts. It's strange how once you get interested in a topic, you start seeing stuff about it everywhere. First the Clojure-based Overtone project, and now this...

Devlin_Donnelly 14y ago
As to why some sets of notes sound good or harmonious and others sound "bad" or dissonant, we find that frequencies with the simplest mathematical ratios tend to sound the most harmonious, while frequencies with more complex ratios sound more dissonant. So for example the simplest ratio 2:1 corresponds to an octave interval. Notes which are an octave apart sound so similar that we describe them with same letter. So concert A is 440Hz and the "A" note one octave higher is 880Hz. The next simplest ratio, 3:2 corresponds to the interval known as a perfect fifth. So given the example of concert A at 440Hz again, one perfect fifth above concert A is the note E which has a frequency of 660Hz as (440 * 3) / 2 = 660. We find the simplest ratios of frequency intervals present in music from cultures the world over. The traditional classical Western twelve-note scale consists of the 12 simplest frequency ratios. In some Eastern music we hear a pentatonic or five note scale, which consists of the five simplest frequency ratios. So this aspect of music we can attribute to innate psycho-acoustics or even physics rather than cultural bias.
- jtheory 14y ago
  > So this aspect of music we can attribute to innate psycho-acoustics or even physics rather than cultural bias. It's inextricable from cultural bias, though the physics obviously plays some role. The cultural bias comes into play more strongly around the question of how much dissonance is "good" vs. "bad", and how the more dissonant bits should interplay with the more consonant bits of music. Certainly, "more consonant = better" isn't true in any culture I can think of.... Imagine an orchestra that tunes up, then they all play the note A in various octaves for 3 hours. Possibly also worth mentioning that this isn't quite correct: > The traditional classical Western twelve-note scale consists of the 12 simplest frequency ratios You're thinking of the major scale, maybe? The ratios for a tritone, major 7th, etc. are more complex (and not the first 12 simplest...) and if you try to actually come up with ratios for an even-tempered scale you're really in trouble.

afandian 14y ago

On a similar note to this, I had great fun writing the keyboard and stave search input for for http://www.folktunefinder.com http://www.folktunefinder.com in JavaScript (you'll find keyboard-xxx.js file in there if you look). (For bonus points the search engine is written in Go).

acarabott 14y ago

I made a quick fork to add audio to this using the Web Audio API (webkit only, tested on Chrome and Safari). http://acarabott.github.com/teoria/ http://acarabott.github.com/teoria/

SoftwareMaven 14y ago
Had fun figuring out where mine and my wife's hearing fell off. Now I know where to put it when I want my kids to bugger off. :)
- cosmikduster 14y ago
  http://onlinetonegenerator.com/ http://onlinetonegenerator.com/ has a nice hearing test using the audio API of Firefox.

robmiller 14y ago

As a once undergrad music student now working in acoustics, thanks for creating this. Something like this has been on my list of things to program, especially with libraries out there like D3.js. Good luck!

DanWaterworth 14y ago

I've never considered the waveform of a chord before, is the reason that some intervals sound harmonious because the period of their combined waves is short?

spiralganglion 14y ago
Yes, exactly.