The Physics of Music

[Nic.]

That's because visible light cover approximately one octave. We also see it in "Color" which does not exist. It is thought bats echo location is percieved in color. The electromagnetic spectrum of which ligtht is a small part, follows many of the same rules as sound, i.e low freqs are omnidirectional, high frequencies are line of sight. There are harmonics etc etc. We hear at very specific frequencies, we percieve only three colors, the frequency spectrum is wide for sight, like only being able to hear three notes with the other notes blurred.

Correct me if I'm wrong, but, isn't pitch perception a continuous spectrum, while we generally detect three basic colours, making wavelength perception somewhat quantized? So, we don't just hear very specific frequencies, but we can perceive both the amplitude and frequency of sound.

Personally, I think this is also why we don't really have the same "octave" and other similar concepts in colour vision- for sound, it's the same receiving tool that takes the input- you have only one eardrum, but it senses all the frequencies coming in; in fact, it only senses pressure, and the frequency is simply how the brain perceives the changes in pressure. You're literally throwing the brain signals at a rate of whatever frequency sound you're hearing. But for frequencies in light, we have molecules that have a peak in resonance at certain frequencies, so rather than feeding "frequencies" into the brain directly, it gives the brain the input that "Blue frequency is incoming" rather than sending a signal to the brain at 6 x 10^14 hertz or so. I doubt the brain can even take in that kind of input anyway, pretty sure 10^-14s is under the limit of response of the brain. Of course, I'm not a biologist so I wouldn't know much about this.

However, I have this suspicion that complimentary colours, and the effect and mood set by specific combinations of colours, also depends on the relationship between their wavelengths. I didn't listen much during my art theory classes, and I'm pretty sure it didn't cover this anyway, but I thought I might as well throw this up in discussion here.

Also, another thing that I was thinking about- Mixing blue and red light will give you purple light, right? But there also exists a certain frequency that is "purple" light (or rather, violet). Can the eye differentiate between this frequency, and the combination of light at "blue" and "red" frequencies together?

Since our ears can perceive two similar frequencies apart based on their harmonics (thus making every bass sound different and leading to severe GAS), is there an equivalent analogue for sight? For instance, in pointilism, a mixture of small red and blue dots appear purple when seen from a distance, but have a slight shimmery or jittery feeling (at least, it's supposed to, so I don't know if my perception of this is affected by my prior knowledge)

 

[theunknowndude]

if were going to bring vision into it, has anyone thought about that disorder where people can perceive sound as vision? pretty sure Adam Jones from Tool has it...

in regards to some of the questions, I think I approach it like Jimmy,... sure some of its interesting and good to know for how to set up my EQ and what not... but id prefer to be learning how to actually play harmonics properly and so on rather than go ahhh there 3/4 of a string...

I use flat fifth quite a bit too, I think pushing the boundaries on what the cultural 'acceptance' of music can be a good thing... sure alot of things are 4/4 and playing root 5th octave sounds natural but that doesn't mean we HAVE to...

this is all YMMV and IMHO etc etc...

 

[Billnc]

Correct me if I'm wrong, but, isn't pitch perception a continuous spectrum, while we generally detect three basic colours, making wavelength perception somewhat quantized? So, we don't just hear very specific frequencies, but we can perceive both the amplitude and frequency of sound.

Personally, I think this is also why we don't really have the same "octave" and other similar concepts in colour vision- for sound, it's the same receiving tool that takes the input- you have only one eardrum, but it senses all the frequencies coming in; in fact, it only senses pressure, and the frequency is simply how the brain perceives the changes in pressure. You're literally throwing the brain signals at a rate of whatever frequency sound you're hearing. But for frequencies in light, we have molecules that have a peak in resonance at certain frequencies, so rather than feeding "frequencies" into the brain directly, it gives the brain the input that "Blue frequency is incoming" rather than sending a signal to the brain at 6 x 10^14 hertz or so. I doubt the brain can even take in that kind of input anyway, pretty sure 10^-14s is under the limit of response of the brain. Of course, I'm not a biologist so I wouldn't know much about this.

However, I have this suspicion that complimentary colours, and the effect and mood set by specific combinations of colours, also depends on the relationship between their wavelengths. I didn't listen much during my art theory classes, and I'm pretty sure it didn't cover this anyway, but I thought I might as well throw this up in discussion here.

Also, another thing that I was thinking about- Mixing blue and red light will give you purple light, right? But there also exists a certain frequency that is "purple" light (or rather, violet). Can the eye differentiate between this frequency, and the combination of light at "blue" and "red" frequencies together?

Since our ears can perceive two similar frequencies apart based on their harmonics (thus making every bass sound different and leading to severe GAS), is there an equivalent analogue for sight? For instance, in pointilism, a mixture of small red and blue dots appear purple when seen from a distance, but have a slight shimmery or jittery feeling (at least, it's supposed to, so I don't know if my perception of this is affected by my prior knowledge)

Pitch perception is frequency specific. You might NOT hear every note in the spectrum, the hairs in your ear vibrate at the specific frequency. Your brain may add a combination tone however. Pressure equals volume to the ear drum. Frequency is a function of vibration rate.

Color is another story altogether. Again it is a manifestation of the mind. Hence synathesia, where you hear in color, or see numbers in color. Also not that mixing different colors has a different effect when you are mixing light or paint. Red and green light yield yellow light, red and green paint, some sort of brown.

You know, I think we might be saying much the same thing.

 

[Nic.]

Ah, I didn't know the ear worked that way. So am I right to say this is how the ear works:

Eardrum receives pressure, reading off the volume
Hairs in ear canal resonates at resonant frequency with sound, reading off the frequency

And then, the signals sent to the brain is a combination of "You are hearing sound at ___db" and "You are hearing sound at ____hz"?

I always just simply assumed that pitch hearing is the brain making sense of the fluctuations in pressure readings off the eardrum.

Yeah, that's what I'm saying about light- it's how the brain makes sense of "we have many blue cones and some red cones reacting"

I'm talking about the mixing of colours purely in terms of light- I don't care where the source is from, what I'm interested in is rather how it is perceived by the eye.

 

[suraci]

They only exist in your head. (really)

So, when a choir of brass players create a combination tone
and they all hear it because it is louder than their actual note

you are saying it is all in their heads??

I thought the combination tone was in the atmosphere

What the psychoacoustical model suggests then, is that for instance, the muddiness is all in our minds, hmmm!!

This is getting into a spooky area for me... notions about "in there" and "out there", kind of thing.... what is real?
For me, I hear the combination tone- that is good enough for me. I use them as a bass player- I will play a fifth on lower strings to create the illusion of a pitch that is lower than my 41 Hz low E. Like a low C and the fifth above creates a 32 Hz combination tone to a degree. This principle is used on giant pipe organs when they want a super Low C at 16 Hz!!!! they use a 32 Hz and a fifth above that to create the 16Hz. If this is an illusion, it is a shared one!

An arranger ought to know about them as well, because merely in the audiences head, the muddiness certainly seems "real".

 

[Billnc]

So, when a choir of brass players create a combination tone
and they all hear it because it is louder than their actual note

you are saying it is all in their heads??

I thought the combination tone was in the atmosphere

What the psychoacoustical model suggests then, is that for instance, the muddiness is all in our minds, hmmm!!

This is getting into a spooky area for me... notions about "in there" and "out there", kind of thing.... what is real?
For me, I hear the combination tone- that is good enough for me. I use them as a bass player- I will play a fifth on lower strings to create the illusion of a pitch that is lower than my 41 Hz low E. Like a low C and the fifth above creates a 32 Hz combination tone to a degree. This principle is used on giant pipe organs when they want a super Low C at 16 Hz!!!! they use a 32 Hz and a fifth above that to create the 16Hz. If this is an illusion, it is a shared one!

An arranger ought to know about them as well, because merely in the audiences head, the muddiness certainly seems "real".

Yes, it is an "aural" illusion not the combination of the waves as previously thought. If you take a couple of sine waves that equal harmoncs of a certain note, your brain adds the low fundamental. Yes it is a shared illusion and a useful one, much like any optical illusion. I believe its around page 43 in "This is Your Brain on Music". Also read "Music in 6 Songs" great books. So... from an arrangers point of view, illusion or real nothing changes. Whats REALLY spooky is you can hear all the instruments in a 110 piece orchestra and pick them out, we do not percieve it as a wall of noise, yet it is ONE sound, THAT's being able percieve sutblties in the harmonic series.

nic. Dawkins got into visual perception in some of his books, I believe in the Ancestors Tale, if memory serves some reptiles have four color receptors, imagine the differences in their sight to ours, also nocturnal animals are shifted to the infrared in their sight. Hard to remember all that so don't quote me! It is a very interesting area of study. It would affect how we go about lighting moods in certain songs etc, though I think we'd all agree on what was wrong!

 

[climb]

Ah, I didn't know the ear worked that way. So am I right to say this is how the ear works:

Eardrum receives pressure, reading off the volume
Hairs in ear canal resonates at resonant frequency with sound, reading off the frequency

And then, the signals sent to the brain is a combination of "You are hearing sound at ___db" and "You are hearing sound at ____hz"?

I always just simply assumed that pitch hearing is the brain making sense of the fluctuations in pressure readings off the eardrum.

Yeah, that's what I'm saying about light- it's how the brain makes sense of "we have many blue cones and some red cones reacting"

I'm talking about the mixing of colours purely in terms of light- I don't care where the source is from, what I'm interested in is rather how it is perceived by the eye.
----
Another poster wrote:
Pitch perception is frequency specific. You might NOT hear every note in the spectrum, the hairs in your ear vibrate at the specific frequency. Your brain may add a combination tone however. Pressure equals volume to the ear drum. Frequency is a function of vibration rate.

Color is another story altogether. Again it is a manifestation of the mind. Hence synathesia, where you hear in color, or see numbers in color. Also not that mixing different colors has a different effect when you are mixing light or paint. Red and green light yield yellow light, red and green paint, some sort of brown.

You know, I think we might be saying much the same thing.

Maybe I can clarify some of this; I'm an ear/hearing specialist and a music/brain researcher.

In the auditory periphery (i.e. the cochlea), pitch perception is based on vibration of the basilar membrane within the cochlea in a frequency-specific manner that is spatially arranged (a property known as tonotopy). The basilar membrane vibrations are sensed by hair cells of the Organ of Corti at the location of the basilar membrane most sensitive to the frequency of the incoming sound. Larger amplitude of vibration/increased sound pressure level leads to increased displacement of the eardrum/ossicular chain and fluid within the inner ear, and increased basilar membrane displacement, leading to greater hair cell motion--too much acoustic information (ex. gunfire near the ear) can lead to shearing of these hair cells and death with resultant hearing loss. But loudness encoding and pitch encoding also have extensive central processing--once a sound is transmitted by the hair cells to the brainstem, it is entirely electrical, and no acoustic properties apply. How we perceive these sounds as louder/softer/different pitches has very little to do with acoustics per se, but rather neural representations/translations of acoustic features. Loudness is not encoded simply by more neurons firing in the brain.

Hope this helps some.

 

[suraci]

Yes, it is an "aural" illusion not the combination of the waves as previously thought.

nic. Dawkins got into visual perception in some of his books, I believe in the Ancestors Tale, if memory serves some reptiles have four color receptors, imagine the differences in their sight to ours, also nocturnal animals are shifted to the infrared in their sight. Hard to remember all that so don't quote me! It is a very interesting area of study. It would affect how we go about lighting moods in certain songs etc, though I think we'd all agree on what was wrong!

I am respectfully skeptical of what the latest science supposedly says ( including man caused global warming- global cooling is still too fresh in this cynic's memory!) about perception in the human mind.
While I respect the scientific method, and truly great scientists - I am still skeptical. With that, let me mention this info about sight that is fascinating and will perhaps distantly relate in your mind to how we hear music.
I quote:

SEEING THE LIGHT - Understanding the true nature of light, says a physicist, requires not looking only throught the eyes but with the soul.
By ARTHUR ZAJONC, \o7 This article is adapted from "Catching the Light," recently published by Bantam Books, 1993 by Arthur Zajonc. Zajonc is a professor at Amherst College\f7
July 25, 1993

IN 1910, TWO FRENCH SURGEONS WROTE about their successful operation on an 8-year-old boy who had been blind since birth because of cataracts. When the boy's eyes were healed, they removed the bandages, eager to discover how well the child could see. Waving a hand in front of the boy's physically perfect eyes, they asked him what he saw. He replied weakly, "I don't know."* "Don't you see it moving?" they asked. * "I don't know" was his only reply. * The boy's eyes were clearly not following the slowly moving hand. What he saw was only a varying brightness in front of him. He was then allowed to touch the hand as it began to move; he cried out in a voice of triumph: "It's moving!" He could feel it move, and even, as he said, "hear it move," but he still needed laboriously to learn to see it move. Passing through the now-clear black pupil of the child's eye, that first light called forth no echoing image from within. The child's sight began as a hollow, silent, dark and frightening kind of seeing. The light of day beckoned, but no light of mind replied within the boy's anxious, open eyes.
The lights of nature and of mind entwine within the eye and call forth vision. Yet separately, each light is mysterious and dark. Even the brightest light can escape our sight.

Science says what is solid is mostly space, but when I punch a wall my hand "sees it" differently... lol

 

[uethanian]

In my opinion it is interesting to learn, but almost useless on a practical level. There are just too many basic philosophical questions unanswered to draw any real helpful conclusions. For example, we know that there is a relation between a fifth over a root "sounding good" and the fact that the frequency of the waves follow a fairly even pattern with each other. But we can't say WHY waves with even patterns sound good to us once our brain registers them. We can't say why certain waves will sound good to us in one timbre, but not in another. Or in one situation, and not in another. It all goes back to the mind/body problem really.

Really, the most important aspect of physics a musician should know is how too loud of a volume effects you and the crowd's ears.

i'm jumping in on this late, but w/e

what's practical is really subjective; most 'bass players' specifically don't benefit much by it, but it becomes necessary once you go outside equal temperament, and also in gaining appreciation for another culture's music. personally speaking, my appreciation of music in general went way up once i understood the physics behind it.

and i don't think they're really 'unanswered' questions; for the most part, people hear simple numerical relationships as consonant (3/2, 4/3, 5/4, etc.) and complex ones as increasingly dissonant (45/32, 81/64, etc.). without bringing too much psychoacoustics into it, it's easy to hypothesize that the brain likes simple and quantifiable stimuli. i mean, it's easy enough to tap out 3-against-2, but try doing 45-against-32...we're just not made to do that kind of computation.

 

[Billnc]

I read the Seeing the Light book. fascinating stuff! There is some other interesting stuff in This is your Brain on Music too. Skeptical or not, correct or not the results of sound and combination tones are the same. We still get to use it, whether its a pheomena or illsuion.

Hey I've survived almost five predicted apocolypses so far! (I'm figuring one for every ten years I've been alive.)

 

[climb]

I am respectfully skeptical of what the latest science supposedly says ( including man caused global warming- global cooling is still too fresh in this cynic's memory!) about perception in the human mind.
While I respect the scientific method, and truly great scientists - I am still skeptical. With that, let me mention this info about sight that is fascinating and will perhaps distantly relate in your mind to how we hear music.
I quote:

SEEING THE LIGHT - Understanding the true nature of light, says a physicist, requires not looking only throught the eyes but with the soul.
By ARTHUR ZAJONC, \o7 This article is adapted from "Catching the Light," recently published by Bantam Books, 1993 by Arthur Zajonc. Zajonc is a professor at Amherst College\f7
July 25, 1993

IN 1910, TWO FRENCH SURGEONS WROTE about their successful operation on an 8-year-old boy who had been blind since birth because of cataracts. When the boy's eyes were healed, they removed the bandages, eager to discover how well the child could see. Waving a hand in front of the boy's physically perfect eyes, they asked him what he saw. He replied weakly, "I don't know."* "Don't you see it moving?" they asked. * "I don't know" was his only reply. * The boy's eyes were clearly not following the slowly moving hand. What he saw was only a varying brightness in front of him. He was then allowed to touch the hand as it began to move; he cried out in a voice of triumph: "It's moving!" He could feel it move, and even, as he said, "hear it move," but he still needed laboriously to learn to see it move. Passing through the now-clear black pupil of the child's eye, that first light called forth no echoing image from within. The child's sight began as a hollow, silent, dark and frightening kind of seeing. The light of day beckoned, but no light of mind replied within the boy's anxious, open eyes.
The lights of nature and of mind entwine within the eye and call forth vision. Yet separately, each light is mysterious and dark. Even the brightest light can escape our sight.

Science says what is solid is mostly space, but when I punch a wall my hand "sees it" differently... lol

Not entirely sure what you're getting at, but the above phenomenon is attributable to a well-known concept of the critical period of neural plasticity. When sensory development occurs in relative deprivation (e.g. deafness, blindness), the central nervous structures that are used to process incoming peripheral information do not develop properly, and become relatively fixed after the first few years of life, when the critical period of development passes. Hence, improving peripheral vision after years of deprivation does not immediately address the central nervous deterioritation/lack of development. This is the same explanation for why deaf children with cochlear implants hear better if they are implanted early than if they are implanted after an 8 year period of deafness, for which outcomes are not nearly as good. This is not to say that scientists understand everything; that's hardly the case. But it's another thing to say that things can't be explained because we can't explain them yet.

 

[Billnc]

Not entirely sure what you're getting at, but the above phenomenon is attributable to a well-known concept of the critical period of neural plasticity. When sensory development occurs in relative deprivation (e.g. deafness, blindness), the central nervous structures that are used to process incoming peripheral information do not develop properly, and become relatively fixed after the first few years of life, when the critical period of development passes. Hence, improving peripheral vision after years of deprivation does not immediately address the central nervous deterioritation/lack of development. This is the same explanation for why deaf children with cochlear implants hear better if they are implanted early than if they are implanted after an 8 year period of deafness, for which outcomes are not nearly as good. This is not to say that scientists understand everything; that's hardly the case. But it's another thing to say that things can't be explained because we can't explain them yet.

I think what we found interesting was the fact that the patients who were given sight had to utilize the senses they had already developed before they could learn to see. There was a blind man who worked a lathe. When they showed him a lathe after he was given sight he couldn't recognize it. Once he touched it he could see it. It took him quite a while to see details etc.

 

[suraci]

I read the Seeing the Light book. fascinating stuff! There is some other interesting stuff in This is your Brain on Music too. Skeptical or not, correct or not the results of sound and combination tones are the same. We still get to use it, whether its a pheomena or illsuion.

Hey I've survived almost five predicted apocolypses so far! (I'm figuring one for every ten years I've been alive.)

Yeah, and I 'm still nervous about GREENland... what's up with that? lol

 

[suraci]

Not entirely sure what you're getting at, .

I am getting at
science is not into consciousness
and as a talented musician, i believe there are many unanswered questions in this business of music- including the major part that the consciousness of the musician and his audience play in music experience. This is outside sciences domain.

"Science" often is driven by factors other than pure science-
i therefore have lowered the value science has in my life in general.

"Science" seems arrogant to me in its pronouncements -at times.
Science has dropped a few pegs, in my estimation.
Nuff said

 

[EADG mx]

What's wrong with a flat 5th?

On a iim7b5 into a V(b9), nothing.

 

[Nic.]

Maybe I can clarify some of this; I'm an ear/hearing specialist and a music/brain researcher.

In the auditory periphery (i.e. the cochlea), pitch perception is based on vibration of the basilar membrane within the cochlea in a frequency-specific manner that is spatially arranged (a property known as tonotopy). The basilar membrane vibrations are sensed by hair cells of the Organ of Corti at the location of the basilar membrane most sensitive to the frequency of the incoming sound. Larger amplitude of vibration/increased sound pressure level leads to increased displacement of the eardrum/ossicular chain and fluid within the inner ear, and increased basilar membrane displacement, leading to greater hair cell motion--too much acoustic information (ex. gunfire near the ear) can lead to shearing of these hair cells and death with resultant hearing loss. But loudness encoding and pitch encoding also have extensive central processing--once a sound is transmitted by the hair cells to the brainstem, it is entirely electrical, and no acoustic properties apply. How we perceive these sounds as louder/softer/different pitches has very little to do with acoustics per se, but rather neural representations/translations of acoustic features. Loudness is not encoded simply by more neurons firing in the brain.

Hope this helps some.

....and this is why I dropped biology and decided to study physics xP

It helps, though! Although I had to look up some of the terms in there.

I would have thought that the loudness was read off as more responses... so am I right to say this? Hairs at different parts of the basilar membrane respond to different frequencies, and how much they respond will give the "loudness" signal to the brain?

So these regions where the hairs are located, are they neatly quantized into frequency ranges, or is it a smooth continuous spectrum across the basilar membrane?

and i don't think they're really 'unanswered' questions; for the most part, people hear simple numerical relationships as consonant (3/2, 4/3, 5/4, etc.) and complex ones as increasingly dissonant (45/32, 81/64, etc.). without bringing too much psychoacoustics into it, it's easy to hypothesize that the brain likes simple and quantifiable stimuli. i mean, it's easy enough to tap out 3-against-2, but try doing 45-against-32...we're just not made to do that kind of computation.

I CAN PLAY 45 AGAINST 32! =D

</ j/k>

Physicist Richard Feynman can play 11 against 10 on the bongos... but I think he mentioned somewhere that any higher than that is pointless because no-one will be able to hear it anyway.

That's one thing I don't like about a lot of contemporary music- I used to have to do several of those every year as part of my orchestra and they called for strange tunings and tempos to set an atmospheric mood- and even after all that effort, most of the audience didn't appreciate it anyway.

The lights of nature and of mind entwine within the eye and call forth vision. Yet separately, each light is mysterious and dark. Even the brightest light can escape our sight.

Science says what is solid is mostly space, but when I punch a wall my hand "sees it" differently... lol

I find this pretty interesting- that vision isn't hard-coded into the brain from birth. I suppose this is why babies have to learn to "focus" their eyes.

Anyway, science says what is solid is mostly space, but then again, a sponge is mostly space yet your hand can't go through it either, right?

I am getting at
science is not into consciousness
and as a talented musician, i believe there are many unanswered questions in this business of music- including the major part that the consciousness of the musician and his audience play in music experience. This is outside sciences domain.

"Science" often is driven by factors other than pure science-
i therefore have lowered the value science has in my life in general.

"Science" seems arrogant to me in its pronouncements -at times.
Science has dropped a few pegs, in my estimation.
Nuff said

I would say it is not science that is lacking, but rather, that we mere mortals lack the sensory input and processing capability needed to understand the universe through science.

Laplace once asked if we could predict the future if we knew every single little nitty gritty detail in the universe. I think we can. Unfortunately, the devil's in the details.

 

[Hoover]

So, just to respond to your thoughtfully put Devil's Advocacy...

How has our physiology evolved to hear simpler frequency multiples as more consonant, do you think? Genuine question.

Is the fact that we hear two frequencies that are related by a factor of two to be very closely related just coincidence? Why 2? Why not 1.547 or 2.219 or 15.614 et cetera et cetera ad infinitum? Are harmonic relationships really just physiological conventions, or do they really have a basis in physical relationships between frequencies?

I suspect the key difference is that simpler harmonic relationships yield soundwaves whose peaks & nulls correllate more regularly/predictably - iow, they're in phase & have shorter periods -- and this phenomenon (which in musical terms yields a more "consonant" relationship) requires less mental activity to parse. The theory (not mine, btw) being that the less brainpower required to parse a phenomenon, the less likely those phenomenon are to trigger an Orienting Response in the central nervous system. Fewer Orienting Responses = Less Stress. Less Stress = More Relaxation. Ergo, humans are ostensibly physiologically predisposed to prefer lower order ratios because they don't invoke a Fight/Flee response.

Which doesn't explain why many people really sincerely like exceedingly dense, complex, non-consonant (sic) music...

Or am I missing your point? You're not claiming that octave up as double the frequency is pure coincidence, surely?

My point was mostly that Frequency is a physical property, but Pitch is a cognitive property. Any correlation between the two has more to do with the evolution of human perception (in response to those physical properties) than it does with inherent qualities of those physical properties.

 

[BassyBill]

My point was mostly that Frequency is a physical property, but Pitch is a cognitive property. Any correlation between the two has more to do with the evolution of human perception (in response to those physical properties) than it does with inherent qualities of those physical properties.

Surely a perceptive response to physical properties can only occur if there's some inherent quality in them to perceive?

Octave in pitch = double frequency (rather than 1.86579...) still seems very, VERY rooted in the physical world to me, rather than purely arbitrary.

 

[Hoover]

Surely a perceptive response to physical properties can only occur if there's some inherent quality in them to perceive?

True, but that's not the same thing as saying "The reason we perceive it this way is because it possesses that physical property."

Think of it this way: Why is the sky blue?

One can cite any number of physical properties that the earth's atmosphere possesses that would explain (sic) why it ought to appear blue to a human being with "normal" optical faculties...but that still doesn't explain why those particular physical properties get interpreted by humans as Blue, rather than, say Magenta, or Chartruese, or Antique Cherry Sunburst.

I'm not saying that the correlation between physical properties & perceptual responses is "arbitrary", just that any definition that doesn't recognize how consciousness & cognition must have evolved to allow us to reach that perception is missing a big chunk of the explanation.

 

[BassyBill]

Gotcha. That makes sense to me, too.

Remember, though, that perceiving a particular wavelength of light and giving that perception the name "blue" is, in fact, pretty arbitrary. But with an octave, for example, we're naming the relationship between perceptions (of sounds). The reason why we do so for some of those relationships, using names like octave and perfect fifth, and not for other intervals (there are an infinity of them, after all) has a real basis in the physical world.

But I think you get this, judging by your last post - just commenting here for clarification.