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why does a major 7th harmonic sound good but a minor 2nd harmonic sound *bad*?

like why does C4 + B4 sound good while B4 + C5 sounds bad?

if there's a music theory mastodon out there please help ;-;

@colleen This drifts from music theory into psychoacoustics.

A lot of what we perceive as consonance or dissonance is down to physics and the way the waveforms interact. When the frequency of the top note is a nice multiple of the bottom note we tend to perceive the interval as consonant. When two notes are a half-step apart, there is no nice multiple between the two fundamental frequencies or the frequencies of their overtones. The result is a more chaotic waveform that sounds dissonant.


Of course there's all sorts of complexity here. Culture affects how we perceive music and studies have a hard time controlling for that.

So does timbre—even within the same instrument. A full, six string chord which sounds nice on a Stratocaster can sound muddy on a PRS because of the latter's fatter tone.

Register matters too. Thirds sound great up high but messy in lower registers.

@colleen I can explain this but not until tomorrow when I'm on the train, exhausted right now.

It has to do with the harmonic series & overtones that are present in each note

You may notice that e.g. a major third that's very low (say, C2 and E2 played together) is "grumblier" than a higher one (say, C5 and E5). Same deal. (Except thirds *should* be in tune with each other; but if you're playing an instrument with equal temperament they won't be).

@colleen basically bc the "gap" between notes in a minor 2nd interval is small enough for the overtones and harmonics to start beating. it's a very dissonant interval

@tom @colleen yea, its something to do with the sound waves and the intersecting of the ripples/waves

@thefishcrow @colleen acoustics are weird, I'm in my 2nd semester of doing music + audio engineering now and I'm still wrapping my head around everything


@thefishcrow @colleen I mean, I've been making music for years before that as well but I'm learning about so many things that I've never actually considered before

@tom @thefishcrow also is it just me or does major 7th get *more* dissonant sounding the higher-pitched the notes are used?

@colleen @thefishcrow ya that might simply be bc of how our hearing works

we don't perceive frequencies in a linear fashion so some things are just more accented

@colleen @thefishcrow also, esp. when we're talking about synths and simple waveforms (like yr basic square, triangle or sawtooth), beating tends to be more noticeable at higher frequencies

@tom @colleen @thefishcrow i'd expect that if you used a pure sine wave, you wouldn't have some of this weirdness (b/c no harmonics)

@tom @colleen @thefishcrow yeah!! except nobody uses pure sine waves like even hammond organ stuff? you almost always have other drawbars out! because your ear is like I WANT MORE HARMONICS

@er1n @colleen @thefishcrow oh yeah if we're talking practical use, you won't really find a "real" and "pure" sine wave anywhere bc those are actually sorta boring?

@er1n @Tom @colleen @thefishcrow clean fender rhodes is near enough to a sine wave that you can approximate it in a mix with one (presuming you want the sound of it played light enough so theres no e.g. 2nd, 3rd, 4th.. harmonics and no tine overtone, which is about 6.5 harmonic or whatever)

@tom @colleen @thefishcrow *pouring dirt into my ear canals* mmmmm getting me some good healthy Analog Sound

@tom interesting

i guess it's just an unexpected outcome because in both cases it's a B and a C, just, the octave is different & it's wild that that octave can change so much

@colleen @tom chords on piano especially can change wildly between octaves!

@er1n @colleen which is also why you can play different inversions of the same chord and get something that sounds completely different despite containing the same notes

@tom @colleen yeah!! and, like, you REALLY need to think about inversions esp when transposing down or stuff gets Really muddy

@er1n @colleen I'm more in the "trying and seeing what happens" camp but yeah, there's a lot to be done wrong

@tom @colleen yeah when i say that i mean, like, you need to Try Stuff Out, not just *select notes* *hit control-down-arrow*

@er1n @colleen it's actually wild how little my music theory brain operates while actually, like, making music? I can talk about it but while I'm doing shit I'm just doing shit

@tom @colleen the only things i pay attention to really are keys and time signatures

@tom @er1n @colleen that's the way to do it right? i think it was Charlie Parker who said something like "learn all you can, then forget all that shit and just play"

@er1n @colleen probably also bc there's another, much more obnoxious, part of my brain that just keeps screaming "OOO KNOBNS............ SNYTHS A SOIZER........."

@tom i just realized every music machine i own but the keystep is black

@er1n @tom black is the objectively correct color for electronics to be

@tom @er1n why do people want their expensive electronics to look filthy as soon as literally anything gets on them

@prophet_goddess @er1n idk what anything yr talking about but most things that get on my devices (dust, maybe fingerprints or w/e) are just as visible (if not even more visible) on black electronics

@colleen @tom Yeah, "narrow" and "wide" octaves can be important when voicing certain chords, like maj7, 7b9, 7#9. Probably others as well, but those are the three I have most experience with.

@colleen while the gap is *theoretically* the same for a major 7th, the harmonics change when the notes/octaves are swapped

@colleen the major 7th is a rly interesting interval in general bc it's also sorta dissonant but it just... works better

@colleen my music major best buddy once tried to explain that dissonance was all about context

In that C4+C#4 will be more clashy than C2+C#5

I have no real explanation I'm afraid but it's the start of something...

@colleen hey! I'm not sure I understand your question... I'll assume you're asking why does one sounds joyful and the other more dark :) it's a bit of psychology here, it's actually a very complicated question. Long story short it's because your brain can't define what emotion it is, so, it sounds bad to you. Very abridged explanation!

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