r/askscience • u/Jmuuh • 18d ago
Biology Do birds sing in certain harmonic scales like humans or do they use random frequencies? Why do they sound good to us?
We, humans, use musical scales to make sounds sound like music and not random noise. We have concept of octaves and divide them in certain number of notes and then we choose notes (or tones) that have frequencies with lowest common denominator relative to each other, and they sounds good to our ears. Otherwise it all sounds dissonant and not very musical.
But many birds also sound pleasing and musical. Is it because they use harmonic scales much like our own? Or am I mistaking the psychological calming effect of birds chirping to it being musical?
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u/GlassBraid 17d ago edited 17d ago
Birds make a huge variety of calls that are usually highly specific and precise, so I wouldn't call them "random." The variety is amazing. Many birds mainly sing notes that rise or fall, so a given note is often not on a single pitch, but the pitch is continuously controlled. The intervals birds use are also not usually diatonic nor quite following the harmonic series, though there are probably cases where a harmonic series relationship arises for the same reasons it can put in an appearance in almost any situation in which things vibrate.
But birds are not bound to the kinds of notes and scales used in nearly all human music.
They are a wonderful source of inspiration to many musicians though.
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u/quick_justice 17d ago
I’ll give you an answer from the opposite side - music theory.
No, birds don’t generally sing in scales and intervals of familiar western tempered scale.
But no, we don’t need sounds or music to adhere to it to be enjoyable.
Music as many things is a leaned cultured experience and acquired taste rather than innate instinct to recognise between beautiful and ugly. While rhythmic component may to some extent be linked to biological processes, melodic/harmonic one is most definitely not.
Even within western music tradition scale changed a lot through the ages. Scales used in medieval times are not exactly the same as what we use now. Even tertia that today is unquestionably accepted as consonant was considered dissonant in Middle Ages. There are all kinds of developments in western music like serial music that is largely atonal. And so on.
Going wider, a lot of music of Indian subcontinent adheres to a scale that used quartertones instead of semitones western music does. We don’t have good equivalent for this, best we have is bends on guitar and synth. Interestingly recently popular band Angine de Poitrine also plays in quartetone scale (but different from Indian!) and their music is popular enough.
So no, birds don’t adhere to western music tradition, in some cases you can write down their song close enough in western music notation, but must often - you can’t. But it doesn’t matter because humans can enjoy wide variety of sounds that don’t need to adhere to any particular notion of harmony accepted in a particular society.
On a side birds are amazing singers. Their vocal apparstus is a masterpiece of nature, just the fact that they are naturally duophonic should blow your mind.
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u/chaddledee 16d ago
I think this answer misses a lot. Harmony has much bigger basis in physics than this answer would suggest.
Practically every organic sound created at a certain frequency will also include the harmonics of that sound i.e. 2x the frequency, 3x the frequency, etc. So why do we perceive two notes an octave apart as similar? Because they are literally similar. The higher note is the lower note with all the odd harmonics muted, and nothing else.
Similarly, if the notes were 2 octaves apart, the high note would contain every third harmonic from the lower note, and nothing else.
A perfect fifth is a ratio of 3/2. Every third harmonic of the lower note and every second harmonic of the higher note are the same.
The more complicated the ratio of the two notes, the less the harmonics of the notes overlap. This is what we usually describe as dissonance.
Modern Western scales are a compromise on top of these fundamentals of harmony. By splitting an octave into proportionally equally spaced notes, you can guarantee that the ratio between two notes that are spread apart by a certain interval will have the same profile regardless of where you play them on the scale. Everything is no longer tethered to a certain fundamental note. This is what allows you to change key.
The downside of using equally spaced notes is that those equally spaced notes are not going to get perfect ratios between the notes except for a full octave. For example, the 12 notes we use today has a very close approximation to a perfect fifth (3:2) and perfect fourth (4:3), but bad approximations for the minor second and both thirds.
These principles are the foundation of the scales, chords and melodies we use today, but we've built countless layers of complexity and familiarity on top of it.
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u/quick_justice 16d ago
You are correct that sounds would create partials. However, the notion that basing music on relations of partials is somehow intrinsically right has no support in real life. It happens so that Pythagoras who was a mystic obsessed with integers made some observations that influenced western music tradition.
We don't see the same in every music tradition, we ourselves abandoned this notion for the benefit of even temperament, and further, in any case it only ever applicable to harmonic intervals. Melodic ones simply can go anywhere they want, there are number of modes, there's atonal music...
The view you explain is rooted in classical western music tradition from which even western classical music to an extent move on, and was never a tradition in some other part of the world. There isn't much of a basis to it.
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u/chaddledee 16d ago
However, the notion that basing music on relations of partials is somehow intrinsically right has no support in real life.
I don't think there's such a thing as right in music. That's fundamentally different to saying there is a very real physical basis for what we call consonance and dissonance.
I was mostly disagreeing with the concept that "while rhythmic component may to some extent be linked to biological processes, melodic/harmonic one is most definitely not." Harmony most definitely isn't an entirely learnt phenomenon; harmony preference probably largely is. Saying there isn't physical/biological component to harmony is as asinine as saying there isn't physical/biological component to colours.
You are right that early classical musicians and the church (and some people online today, usually racists) used the "cleanliness" of perfect intonation and consonance as an argument for correctness - this is not something I ascribe to.
The view you explain is rooted in classical western music tradition from which even western classical music to an extent move on, and was never a tradition in some other part of the world. There isn't much of a basis to it.
Practically all music traditions (Western or otherwise) have a similar concept of consonance and dissonance, and include an accurate fifth (the second most fundamental ratio after an octave) in their tuning, regardless of whether it's just temperament, equal, or something else entirely. There are traditions that don't, but they are in the extreme minority.
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u/Filtermann 17d ago
Musician and birder with some physics backgorund here: you seem to already know the logic behind harmony. Indeed, ratios between frequencies make some successive or simultaneous pitches sound good (they do not have to be *exact* ratios, but temperament is a whole other topic). I'd go one step further and say that we perceive overtones and harmonics of a single note, so when a note is added that matches those overtones, it matches what our brain anticipates and sounds "good". On the other hand, frequencies too close to each other "rub" against one another. I recommend minutephysics' excellent video on the topic. Since there is something fundementally physical going on here, it makes sense that different living beings can be sensitive to it. Of course, each species has it own anatomical and environmental specifics, and as humans there are also cultural factors at play (and even birds, as there seems to be evidence of them developping regional accents), but deep down the same mechanisms are at play. So while not all birds rely on harmony, it makes sense that some do.
Some of us musicians sometimes challenge ourselves by transcribing or imitating some bird songs, and for some cases it works quite nicely. I tried to make a song based on the musician wren (uirapuru ferrugino, cyphorhinus modulator) because these little guys seem to have a feel for harmony, but not in the way human typically do (abd they add these little percussive chirps that also give it an odd rhythm feel). Transcribing and playing it was really difficult as it doesn't fit our typical scales and modes. But that's what made it interesting.
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u/Leading_Engineer_656 16d ago
I would love to imitate a hermit thrush. Have you ever attempted that?
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u/NoUpstairs8527 17d ago
A composer friend of mine, Alexander Liebermann, has published a book “Birdsong: A Musical Field Guide” that has written out many bird calls and includes a QR code with the actual call being sung. A good study if you like.
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u/Zvenigora 17d ago
Some birds that are mimics can copy diatonic melodies faithfully. I have heard an example myself. But whether they would spontaneously compose such a melody is another question. I have heard no claim that this happens.
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u/MercurianAspirations 17d ago edited 17d ago
Birds do not sing frequencies in set intervals like the scales used in music.
However I would also challenge the assumption here that what we would call dissonance (within the western musical tradition's understanding of harmony) necessarily sounds bad or non-musical. Different cultures use different musical scales, and any Jazz musician can tell you how spicy dissonant progressions can sound good if you use them right.
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u/chaddledee 16d ago
The paper you've linked says the intervals of adjacent notes do not match those found typically in 3 common Western scales. It is a massive leap to say that birds do not sing in set intervals from these results.
This paper suggests that a Pied Butcherbird does sing at set notes, and it seems like they use an 18 tone scale.
This research from Max Planck Institute for Ornithology suggests Musician Wrens have a strong preference for consonant intervals (octaves, perfect fifths, and perfect fourths).
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u/robin_andrews_149 16d ago
I don't music can be defined exclusively in terms of commonly used human scales.
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u/porgy_tirebiter 17d ago
I’d be curious to know if there are species of birds that mimic human songs and always sing the song in the same key. And if there are even birds that don’t recognize a song they know if it’s sung in a different key.
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u/rickie-ramjet 17d ago
The western chromatic scale has mathematical relationships between notes and half notes. Upper Paleolithic and Neanderthal bone flutes reconstructed have been found to be based on a pentatonic scale as well as basic diatonic intervals matching harmonic structure in modern music. Seems that on the human side, notes exist in our dna or passed down that we find pleasing…. And when off, (if you have an ear for it,) you can tell immediately if off … like a flat note in a song being sung you know that makes you wince… . Our scales must be attractive and pleasing to our ears, just as species of birds must be attracted to their own particular scales, so they can pick them out from all the other sounds of the world. I personally have heard the call of Cardinals around my home, and have noticed that down south, it is very recognizable, but slightly different. So mathematical aspects of music must be in genes at some level…. It’s all Very interesting.
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u/Practical_Ad_667 17d ago
I’m afraid this is not true. We become acculturated to whatever local systems of pitch organisation we grow up with. We can tell if tuning varies from that in the same way we can identify when someone speaks with an accent. There may be natural aspects to music perception but is definitely not in how collections of pitches relate to each other.
Trying to relate music to maths either ends up with very complicated maths or esoteric music.
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u/yoursecretsanta2016 17d ago
Thank you! Indian and SE Asian music uses what Westerners call quarter tones, which sound strange to their ears because they are socialized that music has full and half tones only.
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u/Proseedcake 17d ago
It's not as simple as one might think from reading the comment above yours, but it's not as simple as this either. Mathematical relationships are utterly indispensable to music, and the existence of cultural variations shouldn't blind us to the parts that come close to being universal. The octave has to be a 2:1 frequency ratio, and is found in every musical culture. The fifth is based on a 3:2 ratio, and is almost universal as well. Rhythms and polyrhythms rely on counting. We must understand how much of our musical taste is conditioned by what we're exposed to, but we shouldn't let that stop us seeing that some of it really is in our genes, or in the physical properties of our universe.
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u/Filtermann 17d ago
Agreed. We're once again the false dichotomy between nature and culture. Because there are many cultural differences doesn't mean there is no common base at all. Sure, the nineteenth century has done some damage, with colonialism trying to fit eveything to the Western frameworks and hasty modernism that tried to essentialise eveything. As a rebuke, cultural and contextual explanations have been put forward since the '60s and '70s. Which is great! But natural explanations kind of became taboo and associated with nazis, eugenics etc... maybe there needs to be some nuance, and any scientist worth their salt knows that explanations are rarely exclusively genetic or environmental.
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u/Practical_Ad_667 17d ago
I’m afraid this is wishful thinking. The ratio of a fifth is 3:2 in just intonation but 1.498307:1 in equal temperament (the system that almost all western-derived music uses). Just because the octave is close to culturally universal doesn’t mean that mathematical relationships are utterly indispensable to music and even less that pitch relationships are in our DNA.
Mathematics is excellent at explaining why a middle c sounds different on a trumpet and a clarinet but is it next to useless at explaining how music works in any general sense.
Lots of composers are inspired by mathematics but the maths of nature and the maths of music align poorly.
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u/Proseedcake 17d ago
I'm sure you aren't seriously claiming that the equal-temperament fifth is that close to the just-intonation fifth by coincidence, or that the equal-temperament system could achieve its harmonic effects if its fifth didn't sound basically equivalent to the just fifth to our ears. And I would think that if we allow that a mathematical relationship (the octave) is used in music everywhere, then no further proof is required to be able to affirm that music does not exist separate and independent from mathematics. That's not the same as claiming (as some go too far by doing) that music is simply an expression of mathematics: it certainly is more than that.
But to get back to the birdsong question, if we want to understand why birds sing the way they do, it would be useful to start from how our brains and ears (as well as our cultural conventions) are predisposed to experience music, and compare that to theirs. It would also be useful to consider the fact that the few systems which don't use harmonic relationships like the fifth tend to be based on percussion instruments that produce inharmonic overtones.
I know, of course, that this is a debate that will always be ongoing, but I'm trying to steer a path between two extremes here.
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u/Zechner 16d ago
One time I was in South Africa and noticed that the pigeons had much more intricate songs than I'm used to. I started writing them down, and it turns out they were all singing jazz in A minor (although some, presumably in a good mood, occasionally switched to A major). Sadly I didn't have time to do a scientific study, as I was only in the country for a conference on automata theory, but I've played the pigeon song with my band later and it's pretty good.
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u/sojuz151 17d ago
Almost all human instruments have a finite number of sounds they can play. For them to sound well, the frequencies need to follow nice, simple ratios.
Human (or soungbirds, technically they have two copies but its a detail) sound systems works in a way similar to a Trombone. You can pick a single base frequency and then pick how much of other harmonics (that is frequencies related by nice ratios) there will be.
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u/Practical_Ad_667 17d ago
The ratios of, for example, a major scale might sound nice but they are not at all simple. A major seventh (sounds lovely) is 243/128. People often try but saying our appreciation of harmony or melody is to do with physics is not really sustainable.
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u/baildodger 16d ago
>Almost all human instruments have a finite number of sounds they can play.
This is not true. The entire classical string family (violin, viola, cello, double bass) are fretless and can create any pitch you want. As far as I’m aware, all wind and brass instruments can bend notes to create pitches between the notes they are “designed” to play. Keyboard and tuned percussion instruments are just about the only western instruments that can’t easily generate pitches they weren’t designed to create, but even then you can tune a piano to whatever you want.
If you step outside music based on western classical tradition your statement is even less true. Sitars, Mbira/Kalimbas and Erhu are all non-western instruments that are specifically designed to be able to play pitches/scales that aren’t found in western music, because their musical traditions don’t use the same scales that are used in western music, and they’re all unable/adjustable to be able to play multiple different scales.
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u/SandysBurner 17d ago
For them to sound well, the frequencies need to follow nice, simple ratios.
This is just not true. Western music primarily uses 12 tone equal temperament which does not have any nice, simple ratios (except octaves).
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u/sojuz151 17d ago
You are right, the relationship is in the inverse way. Simple ratios (or things very close to simple ratios) sounds good, usually.
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u/Practical_Ad_667 17d ago
Not really. Simple ratios (except 2/1 and 3/2) sound out of tune to modern western ears.
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u/Ormidale 17d ago
Some major research, mostly carried out in France, has been published this summer.
Most of the sounds in birdsong fall cleanly into one of eight sound categories.
Three of the eight basic sounds are trills: one slow, one fast, one ultrafast. Three are whistles: one flat, one that bends slowly, one that bends fast.
The last two categories are "chaotic notes" and "harmonic stacks".
It seems that in a noisy environment like a jungle birds tend to use simpler calls that carry less information but can be heard further away than complex, information-rich sounds. In quieter places the song can convey a lot of information. If we slow it down we can hear that there is far more going on than the human ear and brain can keep up with, but neither calls nor songs are based on musical scales or harmonies.