Why can we distinguish different pitches in a chord but not different hues of light?











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In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a superposition waveform, which is obtained by simple addition. This wave is no longer a pure sinusoidal wave.



For example, when you play a low note and a high note on a piano, the resulting sound has a wave that is the mathematical sum of the waves of each note. The same is true for light: when you shine a 500nm wavelength (green light) and a 700nm wavelength (red light) at the same spot on a white surface, the reflection will be a superposition waveform that is the sum of green and red.



My question is about our perception of these combinations. When we hear a chord on a piano, we’re able to discern the pitches that comprise that chord. We’re able to “pick out” that there are two (or three, etc) notes in the chord, and some of us who are musically inclined are even able to sing back each note, and even name it. It could be said that we’re able to decompose a Fourier Series of sound.



But it seems we cannot do this with light. When you shine green and red light together, the reflection appears to be yellow, a “pure hue” of 600nm, rather than an overlay of red and green. We can’t “pick out” the individual colors that were combined. Why is this?



Why can’t we see two hues of light in the same way we’re able to hear two pitches of sound? Is this a characteristic of human psychology? Animal physiology? Or is this due to a fundamental characteristic of electromagnetism?










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  • Closely related questions here and here.
    – knzhou
    yesterday










  • There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
    – carlof
    yesterday






  • 1




    2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
    – MadHatter
    yesterday






  • 3




    Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
    – com.prehensible
    yesterday








  • 1




    @MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
    – chharvey
    yesterday















up vote
44
down vote

favorite
9












In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a superposition waveform, which is obtained by simple addition. This wave is no longer a pure sinusoidal wave.



For example, when you play a low note and a high note on a piano, the resulting sound has a wave that is the mathematical sum of the waves of each note. The same is true for light: when you shine a 500nm wavelength (green light) and a 700nm wavelength (red light) at the same spot on a white surface, the reflection will be a superposition waveform that is the sum of green and red.



My question is about our perception of these combinations. When we hear a chord on a piano, we’re able to discern the pitches that comprise that chord. We’re able to “pick out” that there are two (or three, etc) notes in the chord, and some of us who are musically inclined are even able to sing back each note, and even name it. It could be said that we’re able to decompose a Fourier Series of sound.



But it seems we cannot do this with light. When you shine green and red light together, the reflection appears to be yellow, a “pure hue” of 600nm, rather than an overlay of red and green. We can’t “pick out” the individual colors that were combined. Why is this?



Why can’t we see two hues of light in the same way we’re able to hear two pitches of sound? Is this a characteristic of human psychology? Animal physiology? Or is this due to a fundamental characteristic of electromagnetism?










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  • Closely related questions here and here.
    – knzhou
    yesterday










  • There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
    – carlof
    yesterday






  • 1




    2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
    – MadHatter
    yesterday






  • 3




    Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
    – com.prehensible
    yesterday








  • 1




    @MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
    – chharvey
    yesterday













up vote
44
down vote

favorite
9









up vote
44
down vote

favorite
9






9





In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a superposition waveform, which is obtained by simple addition. This wave is no longer a pure sinusoidal wave.



For example, when you play a low note and a high note on a piano, the resulting sound has a wave that is the mathematical sum of the waves of each note. The same is true for light: when you shine a 500nm wavelength (green light) and a 700nm wavelength (red light) at the same spot on a white surface, the reflection will be a superposition waveform that is the sum of green and red.



My question is about our perception of these combinations. When we hear a chord on a piano, we’re able to discern the pitches that comprise that chord. We’re able to “pick out” that there are two (or three, etc) notes in the chord, and some of us who are musically inclined are even able to sing back each note, and even name it. It could be said that we’re able to decompose a Fourier Series of sound.



But it seems we cannot do this with light. When you shine green and red light together, the reflection appears to be yellow, a “pure hue” of 600nm, rather than an overlay of red and green. We can’t “pick out” the individual colors that were combined. Why is this?



Why can’t we see two hues of light in the same way we’re able to hear two pitches of sound? Is this a characteristic of human psychology? Animal physiology? Or is this due to a fundamental characteristic of electromagnetism?










share|cite|improve this question















In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a superposition waveform, which is obtained by simple addition. This wave is no longer a pure sinusoidal wave.



For example, when you play a low note and a high note on a piano, the resulting sound has a wave that is the mathematical sum of the waves of each note. The same is true for light: when you shine a 500nm wavelength (green light) and a 700nm wavelength (red light) at the same spot on a white surface, the reflection will be a superposition waveform that is the sum of green and red.



My question is about our perception of these combinations. When we hear a chord on a piano, we’re able to discern the pitches that comprise that chord. We’re able to “pick out” that there are two (or three, etc) notes in the chord, and some of us who are musically inclined are even able to sing back each note, and even name it. It could be said that we’re able to decompose a Fourier Series of sound.



But it seems we cannot do this with light. When you shine green and red light together, the reflection appears to be yellow, a “pure hue” of 600nm, rather than an overlay of red and green. We can’t “pick out” the individual colors that were combined. Why is this?



Why can’t we see two hues of light in the same way we’re able to hear two pitches of sound? Is this a characteristic of human psychology? Animal physiology? Or is this due to a fundamental characteristic of electromagnetism?







visible-light waves acoustics biology perception






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edited yesterday









Qmechanic

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asked 2 days ago









chharvey

363312




363312












  • Closely related questions here and here.
    – knzhou
    yesterday










  • There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
    – carlof
    yesterday






  • 1




    2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
    – MadHatter
    yesterday






  • 3




    Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
    – com.prehensible
    yesterday








  • 1




    @MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
    – chharvey
    yesterday


















  • Closely related questions here and here.
    – knzhou
    yesterday










  • There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
    – carlof
    yesterday






  • 1




    2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
    – MadHatter
    yesterday






  • 3




    Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
    – com.prehensible
    yesterday








  • 1




    @MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
    – chharvey
    yesterday
















Closely related questions here and here.
– knzhou
yesterday




Closely related questions here and here.
– knzhou
yesterday












There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
– carlof
yesterday




There's a nice chapter in Vol. 1 of the Feynman Lectures on Mechanics of Seeing. He also touches on the perception of sound at the end of the chapter on Harmonics in a section called non-linear responses. I was just re-reading some of these sections to find some nice tidbit to share here, but as usual his explanation is quite a complete journey. Just jump in.
– carlof
yesterday




1




1




2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
– MadHatter
yesterday




2 beams of different color lights do not superimpose into a single wave form the way sound does. One is a electromagnetic wave the other one is just a pressure traveling through air.
– MadHatter
yesterday




3




3




Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
– com.prehensible
yesterday






Mammals were typically nocturnal in the time of the dinosaurs, that's why they sunburn easily and have whiskers. Only primates have RGB eyesight, dolphins only see green, and most mammals don't see red. Eyes have 3 wavelength sense photoreceptors, ears have have thousands of continuous wavelength sense nerves in a cone-tapered spiral tube. Photons do not merge BTW, sound pressure does.
– com.prehensible
yesterday






1




1




@MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
– chharvey
yesterday




@MadHatter — EM waves are famously known to superimpose, causing constructive/destructive interference, as demonstrated in the double-slit experiment
– chharvey
yesterday










5 Answers
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37
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accepted










Our sensory organs for light and sound work quite differently on a physiological level. The eardrum directly reacts to pressure waves while the photoreceptors on the retina are only senstive to a narrow range around the frequencies associated with red, green and blue. All light frequencies in between partly excite these receptors and the impression of seeing for example yellow arises due to the green and red receptors being exited with certain relative intensities. That's why you can fake out the color spectrum with only 3 different colors at each pixel of the display.



Seeing color in this sense is also more of a useful illusion than direct sensing of physical properties. Mixing colors in the middle of the visible spectrum retains a good approximation of the average frequency of the light mix. If colors from the edges of the spectrum are mixed, i.e. red and blue, the brain invents the color purple or pink to make sense of that sensory input. This however doesn't correspond to the average of the frequencies (which would result in a greenish color) nor does it correspond to any physical frequency of light. Same goes for seeing white or any shade of grey, as these correspond to all receptors being activated with equal intensity.



Mammal eyes also evolved in a way to distinguish intensity rather than color, since most mammals are nocturnal creatures. But I'm not sure if the ability to see in color was only established recently, that would be question for a biologist.






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Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
    – chharvey
    2 days ago






  • 3




    Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
    – Ruslan
    yesterday








  • 9




    Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
    – jamesqf
    yesterday






  • 3




    Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
    – Paŭlo Ebermann
    yesterday






  • 2




    @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
    – chharvey
    yesterday


















up vote
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down vote













This is because of the physiological differences in the functioning of the cochlea (for hearing) and the retina (for color perception).



The cochlea separates out a single channel of complex audio signals into their component frequencies and produces an output signal that represents that decomposition.



The retina instead exhibits what is called metamerism, in which only three sensor types (for R/G/B) are used to encode an output signal that represents the entire spectrum of possible colors as variable combinations of those RGB levels.






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  • 1




    This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
    – Ben Crowell
    yesterday










  • I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
    – chharvey
    yesterday






  • 5




    In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
    – Mark
    yesterday








  • 2




    Exactly. quite a device- until it starts to fail, as mine have!
    – niels nielsen
    yesterday


















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This is due mostly to physiology. There is a fundamental difference in the way we perceive sound vs. light: For sound we can sense actual waveform, whereas for light we can sense only the intensity. To elaborate:




  • Sound waves entering your ear cause synchronous vibrations in your cochlea. Different regions of the cochlea have tiny hairs which vibrate in a frequency-selective way. The vibrations of these hairs are turned into electrical signals which are passed on to the brain. Due to the frequency selectivity of the hairs, the cochlea essentially performs a Fourier transform, which is why we can perceive superpositions of waves.


  • Light has such a high frequency that almost nothing can resolve the actual waveform (even state of the art electronics nowadays cannot do this). All we can effectively measure is the intensity of the light, and this is all that the eyes can perceive as well. Knowing the intensity of a light beam is not sufficient to determine its spectral content. E.g. a superposition of two monochromatic waves can have the same intensity as a pure monochromatic wave of a different frequency.



    We can differentiate superpositions of light in a limited way, due to the fact that eyes perceive three separate color channels (roughly RGB). This is why we can distinguish equal intensities of red and blue light. People with colorblindness have a defective receptor, and so color combinations that most humans can distinguish appear identical to them.



    Not all colors that we perceive correspond to a color of a monochromatic light wave. Famously, there is an entire "line of purples" which do not represent any monochromatic light wave. So for people trained in distinguishing purple colors, they can actually differentiate superpositions of light waves in a limited way.



    enter image description here








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  • 5




    "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
    – Emil
    yesterday










  • @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
    – Yly
    yesterday










  • @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
    – zwol
    yesterday










  • @zwol Thanks. I have corrected the answer accordingly.
    – Yly
    yesterday






  • 2




    I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
    – jamesqf
    14 hours ago


















up vote
7
down vote













Rod (1 type) plus cone (3 types) neurons in the eye give you the potential for 4-D sensation.
Since the rod signal is nearly redundant to the totality of cone signals, this is effectively a 3-D sensation.



Cochlear (roughly 3500 "types" simply due to 3500 different inner hair positions) neurons
in the ear give you the potential for 3500-D sensation, so trained ears can potentially
recognize the simulatenous amplitudes from thousands of frequencies.



So, to answer your question, eyes simply didn't evolve to have many cone types. An improvement, however, is seen through the eyes of mantis shrimp (with the potential for 16-D sensation). Notice the trade-off between spatial image resolution and color perception (and that audio spatial resolution was less important in evolution, and more difficult due to the longer wavelength).






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    Actually you can discern the different combinations to some extent. I figured this out after taking many art classes, particularly color theory and painting. I really started noticing the effect after the painting class. The reason is I was taught how to mix colors and needed to learn to see and think about the combinations while looking at the subject. This is the same for the note discernment you mentioned. The people who are usually able to do it, and especially well, are people who have studied music and have had to learn to hear and think about the combinations while listening.



    So, now when I look at something "green" I see that it is actually blue with a little yellow and sometimes a bit of another color. Nothing is ever "white" or "black" to me anymore either, there is always a reflected color or a texture of some sort which catches the light from the surrounding sources.



    Edit:
    After further consideration I am inclined to say the question posted here is backwards. We actually discern many more separate colors in combination and at the same time than we do sounds. Look around and you will see a plethora of color combinations. We are actually perceiving many billions of separate photons coming from many billions of separate locations in our field of view. In contrast, listening to so many separate sounds would overwhelm our ears and perception of the sounds to the point of hearing only discord, static, or hissing like noises that have no meaning. It is only the combination of very few separate noises which can be discerned.






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    • You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
      – Kaz
      2 hours ago










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    5 Answers
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    5 Answers
    5






    active

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    active

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    active

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    up vote
    37
    down vote



    accepted










    Our sensory organs for light and sound work quite differently on a physiological level. The eardrum directly reacts to pressure waves while the photoreceptors on the retina are only senstive to a narrow range around the frequencies associated with red, green and blue. All light frequencies in between partly excite these receptors and the impression of seeing for example yellow arises due to the green and red receptors being exited with certain relative intensities. That's why you can fake out the color spectrum with only 3 different colors at each pixel of the display.



    Seeing color in this sense is also more of a useful illusion than direct sensing of physical properties. Mixing colors in the middle of the visible spectrum retains a good approximation of the average frequency of the light mix. If colors from the edges of the spectrum are mixed, i.e. red and blue, the brain invents the color purple or pink to make sense of that sensory input. This however doesn't correspond to the average of the frequencies (which would result in a greenish color) nor does it correspond to any physical frequency of light. Same goes for seeing white or any shade of grey, as these correspond to all receptors being activated with equal intensity.



    Mammal eyes also evolved in a way to distinguish intensity rather than color, since most mammals are nocturnal creatures. But I'm not sure if the ability to see in color was only established recently, that would be question for a biologist.






    share|cite|improve this answer








    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.


















    • awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
      – chharvey
      2 days ago






    • 3




      Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
      – Ruslan
      yesterday








    • 9




      Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
      – jamesqf
      yesterday






    • 3




      Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
      – Paŭlo Ebermann
      yesterday






    • 2




      @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
      – chharvey
      yesterday















    up vote
    37
    down vote



    accepted










    Our sensory organs for light and sound work quite differently on a physiological level. The eardrum directly reacts to pressure waves while the photoreceptors on the retina are only senstive to a narrow range around the frequencies associated with red, green and blue. All light frequencies in between partly excite these receptors and the impression of seeing for example yellow arises due to the green and red receptors being exited with certain relative intensities. That's why you can fake out the color spectrum with only 3 different colors at each pixel of the display.



    Seeing color in this sense is also more of a useful illusion than direct sensing of physical properties. Mixing colors in the middle of the visible spectrum retains a good approximation of the average frequency of the light mix. If colors from the edges of the spectrum are mixed, i.e. red and blue, the brain invents the color purple or pink to make sense of that sensory input. This however doesn't correspond to the average of the frequencies (which would result in a greenish color) nor does it correspond to any physical frequency of light. Same goes for seeing white or any shade of grey, as these correspond to all receptors being activated with equal intensity.



    Mammal eyes also evolved in a way to distinguish intensity rather than color, since most mammals are nocturnal creatures. But I'm not sure if the ability to see in color was only established recently, that would be question for a biologist.






    share|cite|improve this answer








    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.


















    • awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
      – chharvey
      2 days ago






    • 3




      Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
      – Ruslan
      yesterday








    • 9




      Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
      – jamesqf
      yesterday






    • 3




      Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
      – Paŭlo Ebermann
      yesterday






    • 2




      @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
      – chharvey
      yesterday













    up vote
    37
    down vote



    accepted







    up vote
    37
    down vote



    accepted






    Our sensory organs for light and sound work quite differently on a physiological level. The eardrum directly reacts to pressure waves while the photoreceptors on the retina are only senstive to a narrow range around the frequencies associated with red, green and blue. All light frequencies in between partly excite these receptors and the impression of seeing for example yellow arises due to the green and red receptors being exited with certain relative intensities. That's why you can fake out the color spectrum with only 3 different colors at each pixel of the display.



    Seeing color in this sense is also more of a useful illusion than direct sensing of physical properties. Mixing colors in the middle of the visible spectrum retains a good approximation of the average frequency of the light mix. If colors from the edges of the spectrum are mixed, i.e. red and blue, the brain invents the color purple or pink to make sense of that sensory input. This however doesn't correspond to the average of the frequencies (which would result in a greenish color) nor does it correspond to any physical frequency of light. Same goes for seeing white or any shade of grey, as these correspond to all receptors being activated with equal intensity.



    Mammal eyes also evolved in a way to distinguish intensity rather than color, since most mammals are nocturnal creatures. But I'm not sure if the ability to see in color was only established recently, that would be question for a biologist.






    share|cite|improve this answer








    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    Our sensory organs for light and sound work quite differently on a physiological level. The eardrum directly reacts to pressure waves while the photoreceptors on the retina are only senstive to a narrow range around the frequencies associated with red, green and blue. All light frequencies in between partly excite these receptors and the impression of seeing for example yellow arises due to the green and red receptors being exited with certain relative intensities. That's why you can fake out the color spectrum with only 3 different colors at each pixel of the display.



    Seeing color in this sense is also more of a useful illusion than direct sensing of physical properties. Mixing colors in the middle of the visible spectrum retains a good approximation of the average frequency of the light mix. If colors from the edges of the spectrum are mixed, i.e. red and blue, the brain invents the color purple or pink to make sense of that sensory input. This however doesn't correspond to the average of the frequencies (which would result in a greenish color) nor does it correspond to any physical frequency of light. Same goes for seeing white or any shade of grey, as these correspond to all receptors being activated with equal intensity.



    Mammal eyes also evolved in a way to distinguish intensity rather than color, since most mammals are nocturnal creatures. But I'm not sure if the ability to see in color was only established recently, that would be question for a biologist.







    share|cite|improve this answer








    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    share|cite|improve this answer



    share|cite|improve this answer






    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    answered 2 days ago









    Halberd Rejoyceth

    57815




    57815




    New contributor




    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.





    New contributor





    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    Halberd Rejoyceth is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.












    • awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
      – chharvey
      2 days ago






    • 3




      Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
      – Ruslan
      yesterday








    • 9




      Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
      – jamesqf
      yesterday






    • 3




      Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
      – Paŭlo Ebermann
      yesterday






    • 2




      @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
      – chharvey
      yesterday


















    • awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
      – chharvey
      2 days ago






    • 3




      Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
      – Ruslan
      yesterday








    • 9




      Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
      – jamesqf
      yesterday






    • 3




      Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
      – Paŭlo Ebermann
      yesterday






    • 2




      @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
      – chharvey
      yesterday
















    awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
    – chharvey
    2 days ago




    awesome! BTW this could help answer your biological question: en.wikipedia.org/wiki/Diurnality#Evolution_of_diurnality
    – chharvey
    2 days ago




    3




    3




    Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
    – Ruslan
    yesterday






    Note that you cannot actually fake all the colors using only three primaries. Human-visible color gamut is not a triangle, so some colors will always be outside of output gamut of your display device.
    – Ruslan
    yesterday






    9




    9




    Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
    – jamesqf
    yesterday




    Perhaps a nitpick, but it's not the eardrum that detects sound. It's more of a transmission device. The actual sensory organ is the cochlea en.wikipedia.org/wiki/Cochlea It's a spiral-shaped tube with sensory hairs along it. Sounds of a particular frequency vibrate the hairs at the spot in the cochlea where the sound resonates. So sound sensing is effectively continuous, while color sensing depends on the mix of the 3 color sensors.
    – jamesqf
    yesterday




    3




    3




    Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
    – Paŭlo Ebermann
    yesterday




    Actually, the photoreceptors are sensitive to quite large bands (compared to the distance of their peaks), even overlapping ones.
    – Paŭlo Ebermann
    yesterday




    2




    2




    @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
    – chharvey
    yesterday




    @HalberdRejoyceth, yes, please do update. I chose your answer because it hit the underlying point—that our ears sense true waveforms while our eyes do not. I found that to sufficiently answer my question, even if it’s not the complete truth. However, I do think you would benefit the community to explain in further detail the differences in how the cochlea and the retina work.
    – chharvey
    yesterday










    up vote
    43
    down vote













    This is because of the physiological differences in the functioning of the cochlea (for hearing) and the retina (for color perception).



    The cochlea separates out a single channel of complex audio signals into their component frequencies and produces an output signal that represents that decomposition.



    The retina instead exhibits what is called metamerism, in which only three sensor types (for R/G/B) are used to encode an output signal that represents the entire spectrum of possible colors as variable combinations of those RGB levels.






    share|cite|improve this answer

















    • 1




      This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
      – Ben Crowell
      yesterday










    • I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
      – chharvey
      yesterday






    • 5




      In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
      – Mark
      yesterday








    • 2




      Exactly. quite a device- until it starts to fail, as mine have!
      – niels nielsen
      yesterday















    up vote
    43
    down vote













    This is because of the physiological differences in the functioning of the cochlea (for hearing) and the retina (for color perception).



    The cochlea separates out a single channel of complex audio signals into their component frequencies and produces an output signal that represents that decomposition.



    The retina instead exhibits what is called metamerism, in which only three sensor types (for R/G/B) are used to encode an output signal that represents the entire spectrum of possible colors as variable combinations of those RGB levels.






    share|cite|improve this answer

















    • 1




      This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
      – Ben Crowell
      yesterday










    • I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
      – chharvey
      yesterday






    • 5




      In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
      – Mark
      yesterday








    • 2




      Exactly. quite a device- until it starts to fail, as mine have!
      – niels nielsen
      yesterday













    up vote
    43
    down vote










    up vote
    43
    down vote









    This is because of the physiological differences in the functioning of the cochlea (for hearing) and the retina (for color perception).



    The cochlea separates out a single channel of complex audio signals into their component frequencies and produces an output signal that represents that decomposition.



    The retina instead exhibits what is called metamerism, in which only three sensor types (for R/G/B) are used to encode an output signal that represents the entire spectrum of possible colors as variable combinations of those RGB levels.






    share|cite|improve this answer












    This is because of the physiological differences in the functioning of the cochlea (for hearing) and the retina (for color perception).



    The cochlea separates out a single channel of complex audio signals into their component frequencies and produces an output signal that represents that decomposition.



    The retina instead exhibits what is called metamerism, in which only three sensor types (for R/G/B) are used to encode an output signal that represents the entire spectrum of possible colors as variable combinations of those RGB levels.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered 2 days ago









    niels nielsen

    14k42346




    14k42346








    • 1




      This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
      – Ben Crowell
      yesterday










    • I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
      – chharvey
      yesterday






    • 5




      In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
      – Mark
      yesterday








    • 2




      Exactly. quite a device- until it starts to fail, as mine have!
      – niels nielsen
      yesterday














    • 1




      This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
      – Ben Crowell
      yesterday










    • I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
      – chharvey
      yesterday






    • 5




      In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
      – Mark
      yesterday








    • 2




      Exactly. quite a device- until it starts to fail, as mine have!
      – niels nielsen
      yesterday








    1




    1




    This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
    – Ben Crowell
    yesterday




    This is the only answer so far that correctly focuses on the role of the cochlea. This is a better answer than the accepted answer.
    – Ben Crowell
    yesterday












    I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
    – chharvey
    yesterday




    I agree that this answer is more technically correct, but I think it’s missing the key point: that our ears are able to sense mechanical waveforms while our eyes cannot sense electromagnetic waveforms. There’s room for improvement, which I welcome.
    – chharvey
    yesterday




    5




    5




    In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
    – Mark
    yesterday






    In short, the reason "it could be said that we’re able to decompose a Fourier Series of sound" is because that's exactly what the cochlea does.
    – Mark
    yesterday






    2




    2




    Exactly. quite a device- until it starts to fail, as mine have!
    – niels nielsen
    yesterday




    Exactly. quite a device- until it starts to fail, as mine have!
    – niels nielsen
    yesterday










    up vote
    15
    down vote













    This is due mostly to physiology. There is a fundamental difference in the way we perceive sound vs. light: For sound we can sense actual waveform, whereas for light we can sense only the intensity. To elaborate:




    • Sound waves entering your ear cause synchronous vibrations in your cochlea. Different regions of the cochlea have tiny hairs which vibrate in a frequency-selective way. The vibrations of these hairs are turned into electrical signals which are passed on to the brain. Due to the frequency selectivity of the hairs, the cochlea essentially performs a Fourier transform, which is why we can perceive superpositions of waves.


    • Light has such a high frequency that almost nothing can resolve the actual waveform (even state of the art electronics nowadays cannot do this). All we can effectively measure is the intensity of the light, and this is all that the eyes can perceive as well. Knowing the intensity of a light beam is not sufficient to determine its spectral content. E.g. a superposition of two monochromatic waves can have the same intensity as a pure monochromatic wave of a different frequency.



      We can differentiate superpositions of light in a limited way, due to the fact that eyes perceive three separate color channels (roughly RGB). This is why we can distinguish equal intensities of red and blue light. People with colorblindness have a defective receptor, and so color combinations that most humans can distinguish appear identical to them.



      Not all colors that we perceive correspond to a color of a monochromatic light wave. Famously, there is an entire "line of purples" which do not represent any monochromatic light wave. So for people trained in distinguishing purple colors, they can actually differentiate superpositions of light waves in a limited way.



      enter image description here








    share|cite|improve this answer



















    • 5




      "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
      – Emil
      yesterday










    • @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
      – Yly
      yesterday










    • @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
      – zwol
      yesterday










    • @zwol Thanks. I have corrected the answer accordingly.
      – Yly
      yesterday






    • 2




      I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
      – jamesqf
      14 hours ago















    up vote
    15
    down vote













    This is due mostly to physiology. There is a fundamental difference in the way we perceive sound vs. light: For sound we can sense actual waveform, whereas for light we can sense only the intensity. To elaborate:




    • Sound waves entering your ear cause synchronous vibrations in your cochlea. Different regions of the cochlea have tiny hairs which vibrate in a frequency-selective way. The vibrations of these hairs are turned into electrical signals which are passed on to the brain. Due to the frequency selectivity of the hairs, the cochlea essentially performs a Fourier transform, which is why we can perceive superpositions of waves.


    • Light has such a high frequency that almost nothing can resolve the actual waveform (even state of the art electronics nowadays cannot do this). All we can effectively measure is the intensity of the light, and this is all that the eyes can perceive as well. Knowing the intensity of a light beam is not sufficient to determine its spectral content. E.g. a superposition of two monochromatic waves can have the same intensity as a pure monochromatic wave of a different frequency.



      We can differentiate superpositions of light in a limited way, due to the fact that eyes perceive three separate color channels (roughly RGB). This is why we can distinguish equal intensities of red and blue light. People with colorblindness have a defective receptor, and so color combinations that most humans can distinguish appear identical to them.



      Not all colors that we perceive correspond to a color of a monochromatic light wave. Famously, there is an entire "line of purples" which do not represent any monochromatic light wave. So for people trained in distinguishing purple colors, they can actually differentiate superpositions of light waves in a limited way.



      enter image description here








    share|cite|improve this answer



















    • 5




      "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
      – Emil
      yesterday










    • @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
      – Yly
      yesterday










    • @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
      – zwol
      yesterday










    • @zwol Thanks. I have corrected the answer accordingly.
      – Yly
      yesterday






    • 2




      I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
      – jamesqf
      14 hours ago













    up vote
    15
    down vote










    up vote
    15
    down vote









    This is due mostly to physiology. There is a fundamental difference in the way we perceive sound vs. light: For sound we can sense actual waveform, whereas for light we can sense only the intensity. To elaborate:




    • Sound waves entering your ear cause synchronous vibrations in your cochlea. Different regions of the cochlea have tiny hairs which vibrate in a frequency-selective way. The vibrations of these hairs are turned into electrical signals which are passed on to the brain. Due to the frequency selectivity of the hairs, the cochlea essentially performs a Fourier transform, which is why we can perceive superpositions of waves.


    • Light has such a high frequency that almost nothing can resolve the actual waveform (even state of the art electronics nowadays cannot do this). All we can effectively measure is the intensity of the light, and this is all that the eyes can perceive as well. Knowing the intensity of a light beam is not sufficient to determine its spectral content. E.g. a superposition of two monochromatic waves can have the same intensity as a pure monochromatic wave of a different frequency.



      We can differentiate superpositions of light in a limited way, due to the fact that eyes perceive three separate color channels (roughly RGB). This is why we can distinguish equal intensities of red and blue light. People with colorblindness have a defective receptor, and so color combinations that most humans can distinguish appear identical to them.



      Not all colors that we perceive correspond to a color of a monochromatic light wave. Famously, there is an entire "line of purples" which do not represent any monochromatic light wave. So for people trained in distinguishing purple colors, they can actually differentiate superpositions of light waves in a limited way.



      enter image description here








    share|cite|improve this answer














    This is due mostly to physiology. There is a fundamental difference in the way we perceive sound vs. light: For sound we can sense actual waveform, whereas for light we can sense only the intensity. To elaborate:




    • Sound waves entering your ear cause synchronous vibrations in your cochlea. Different regions of the cochlea have tiny hairs which vibrate in a frequency-selective way. The vibrations of these hairs are turned into electrical signals which are passed on to the brain. Due to the frequency selectivity of the hairs, the cochlea essentially performs a Fourier transform, which is why we can perceive superpositions of waves.


    • Light has such a high frequency that almost nothing can resolve the actual waveform (even state of the art electronics nowadays cannot do this). All we can effectively measure is the intensity of the light, and this is all that the eyes can perceive as well. Knowing the intensity of a light beam is not sufficient to determine its spectral content. E.g. a superposition of two monochromatic waves can have the same intensity as a pure monochromatic wave of a different frequency.



      We can differentiate superpositions of light in a limited way, due to the fact that eyes perceive three separate color channels (roughly RGB). This is why we can distinguish equal intensities of red and blue light. People with colorblindness have a defective receptor, and so color combinations that most humans can distinguish appear identical to them.



      Not all colors that we perceive correspond to a color of a monochromatic light wave. Famously, there is an entire "line of purples" which do not represent any monochromatic light wave. So for people trained in distinguishing purple colors, they can actually differentiate superpositions of light waves in a limited way.



      enter image description here









    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited yesterday

























    answered 2 days ago









    Yly

    1,196420




    1,196420








    • 5




      "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
      – Emil
      yesterday










    • @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
      – Yly
      yesterday










    • @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
      – zwol
      yesterday










    • @zwol Thanks. I have corrected the answer accordingly.
      – Yly
      yesterday






    • 2




      I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
      – jamesqf
      14 hours ago














    • 5




      "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
      – Emil
      yesterday










    • @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
      – Yly
      yesterday










    • @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
      – zwol
      yesterday










    • @zwol Thanks. I have corrected the answer accordingly.
      – Yly
      yesterday






    • 2




      I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
      – jamesqf
      14 hours ago








    5




    5




    "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
    – Emil
    yesterday




    "...electrical signals representing the actual waveform of the sound. The brain ... does a Fourier transform..." This part of your answer is unfortunately incorrect. The decomposition into different audio frequencies happens mechanically in the cochlear before any vibrations are turned into nerve signals. So the actual waveform is not send to the brain.
    – Emil
    yesterday












    @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
    – Yly
    yesterday




    @Emil Do you have a reference for that? I'm not an expert, so I would happily revise my answer with better information, but my understanding is that the eardrum passes sound waves into the fluid of the cochlea, which cause stereocilia in the organ of Corti to vibrate, which in turn mechanically activate certain neurotransmitter channels. It's described on the Wikipedia page for organ of Corti. I see no reference to frequency discrimination in the cochlea.
    – Yly
    yesterday












    @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
    – zwol
    yesterday




    @Yly Emil is correct; the cochlea does the Fourier transform, mechanically. See cochlea.eu/en/cochlea/function
    – zwol
    yesterday












    @zwol Thanks. I have corrected the answer accordingly.
    – Yly
    yesterday




    @zwol Thanks. I have corrected the answer accordingly.
    – Yly
    yesterday




    2




    2




    I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
    – jamesqf
    14 hours ago




    I'm not sure about your 2nd point. Surely a simple spectrograph does a good job of resolving light frequencies? But eyes are arranged primarily for spatial discrimination, rather than frequency, like the ear. If we wanted one organ to do both, it'd need far more sensors: each rod/cone in an eye would need a separate neuron for each frequency band you want to discriminate.
    – jamesqf
    14 hours ago










    up vote
    7
    down vote













    Rod (1 type) plus cone (3 types) neurons in the eye give you the potential for 4-D sensation.
    Since the rod signal is nearly redundant to the totality of cone signals, this is effectively a 3-D sensation.



    Cochlear (roughly 3500 "types" simply due to 3500 different inner hair positions) neurons
    in the ear give you the potential for 3500-D sensation, so trained ears can potentially
    recognize the simulatenous amplitudes from thousands of frequencies.



    So, to answer your question, eyes simply didn't evolve to have many cone types. An improvement, however, is seen through the eyes of mantis shrimp (with the potential for 16-D sensation). Notice the trade-off between spatial image resolution and color perception (and that audio spatial resolution was less important in evolution, and more difficult due to the longer wavelength).






    share|cite|improve this answer

























      up vote
      7
      down vote













      Rod (1 type) plus cone (3 types) neurons in the eye give you the potential for 4-D sensation.
      Since the rod signal is nearly redundant to the totality of cone signals, this is effectively a 3-D sensation.



      Cochlear (roughly 3500 "types" simply due to 3500 different inner hair positions) neurons
      in the ear give you the potential for 3500-D sensation, so trained ears can potentially
      recognize the simulatenous amplitudes from thousands of frequencies.



      So, to answer your question, eyes simply didn't evolve to have many cone types. An improvement, however, is seen through the eyes of mantis shrimp (with the potential for 16-D sensation). Notice the trade-off between spatial image resolution and color perception (and that audio spatial resolution was less important in evolution, and more difficult due to the longer wavelength).






      share|cite|improve this answer























        up vote
        7
        down vote










        up vote
        7
        down vote









        Rod (1 type) plus cone (3 types) neurons in the eye give you the potential for 4-D sensation.
        Since the rod signal is nearly redundant to the totality of cone signals, this is effectively a 3-D sensation.



        Cochlear (roughly 3500 "types" simply due to 3500 different inner hair positions) neurons
        in the ear give you the potential for 3500-D sensation, so trained ears can potentially
        recognize the simulatenous amplitudes from thousands of frequencies.



        So, to answer your question, eyes simply didn't evolve to have many cone types. An improvement, however, is seen through the eyes of mantis shrimp (with the potential for 16-D sensation). Notice the trade-off between spatial image resolution and color perception (and that audio spatial resolution was less important in evolution, and more difficult due to the longer wavelength).






        share|cite|improve this answer












        Rod (1 type) plus cone (3 types) neurons in the eye give you the potential for 4-D sensation.
        Since the rod signal is nearly redundant to the totality of cone signals, this is effectively a 3-D sensation.



        Cochlear (roughly 3500 "types" simply due to 3500 different inner hair positions) neurons
        in the ear give you the potential for 3500-D sensation, so trained ears can potentially
        recognize the simulatenous amplitudes from thousands of frequencies.



        So, to answer your question, eyes simply didn't evolve to have many cone types. An improvement, however, is seen through the eyes of mantis shrimp (with the potential for 16-D sensation). Notice the trade-off between spatial image resolution and color perception (and that audio spatial resolution was less important in evolution, and more difficult due to the longer wavelength).







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered yesterday









        bobuhito

        6441510




        6441510






















            up vote
            0
            down vote













            Actually you can discern the different combinations to some extent. I figured this out after taking many art classes, particularly color theory and painting. I really started noticing the effect after the painting class. The reason is I was taught how to mix colors and needed to learn to see and think about the combinations while looking at the subject. This is the same for the note discernment you mentioned. The people who are usually able to do it, and especially well, are people who have studied music and have had to learn to hear and think about the combinations while listening.



            So, now when I look at something "green" I see that it is actually blue with a little yellow and sometimes a bit of another color. Nothing is ever "white" or "black" to me anymore either, there is always a reflected color or a texture of some sort which catches the light from the surrounding sources.



            Edit:
            After further consideration I am inclined to say the question posted here is backwards. We actually discern many more separate colors in combination and at the same time than we do sounds. Look around and you will see a plethora of color combinations. We are actually perceiving many billions of separate photons coming from many billions of separate locations in our field of view. In contrast, listening to so many separate sounds would overwhelm our ears and perception of the sounds to the point of hearing only discord, static, or hissing like noises that have no meaning. It is only the combination of very few separate noises which can be discerned.






            share|cite|improve this answer























            • You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
              – Kaz
              2 hours ago















            up vote
            0
            down vote













            Actually you can discern the different combinations to some extent. I figured this out after taking many art classes, particularly color theory and painting. I really started noticing the effect after the painting class. The reason is I was taught how to mix colors and needed to learn to see and think about the combinations while looking at the subject. This is the same for the note discernment you mentioned. The people who are usually able to do it, and especially well, are people who have studied music and have had to learn to hear and think about the combinations while listening.



            So, now when I look at something "green" I see that it is actually blue with a little yellow and sometimes a bit of another color. Nothing is ever "white" or "black" to me anymore either, there is always a reflected color or a texture of some sort which catches the light from the surrounding sources.



            Edit:
            After further consideration I am inclined to say the question posted here is backwards. We actually discern many more separate colors in combination and at the same time than we do sounds. Look around and you will see a plethora of color combinations. We are actually perceiving many billions of separate photons coming from many billions of separate locations in our field of view. In contrast, listening to so many separate sounds would overwhelm our ears and perception of the sounds to the point of hearing only discord, static, or hissing like noises that have no meaning. It is only the combination of very few separate noises which can be discerned.






            share|cite|improve this answer























            • You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
              – Kaz
              2 hours ago













            up vote
            0
            down vote










            up vote
            0
            down vote









            Actually you can discern the different combinations to some extent. I figured this out after taking many art classes, particularly color theory and painting. I really started noticing the effect after the painting class. The reason is I was taught how to mix colors and needed to learn to see and think about the combinations while looking at the subject. This is the same for the note discernment you mentioned. The people who are usually able to do it, and especially well, are people who have studied music and have had to learn to hear and think about the combinations while listening.



            So, now when I look at something "green" I see that it is actually blue with a little yellow and sometimes a bit of another color. Nothing is ever "white" or "black" to me anymore either, there is always a reflected color or a texture of some sort which catches the light from the surrounding sources.



            Edit:
            After further consideration I am inclined to say the question posted here is backwards. We actually discern many more separate colors in combination and at the same time than we do sounds. Look around and you will see a plethora of color combinations. We are actually perceiving many billions of separate photons coming from many billions of separate locations in our field of view. In contrast, listening to so many separate sounds would overwhelm our ears and perception of the sounds to the point of hearing only discord, static, or hissing like noises that have no meaning. It is only the combination of very few separate noises which can be discerned.






            share|cite|improve this answer














            Actually you can discern the different combinations to some extent. I figured this out after taking many art classes, particularly color theory and painting. I really started noticing the effect after the painting class. The reason is I was taught how to mix colors and needed to learn to see and think about the combinations while looking at the subject. This is the same for the note discernment you mentioned. The people who are usually able to do it, and especially well, are people who have studied music and have had to learn to hear and think about the combinations while listening.



            So, now when I look at something "green" I see that it is actually blue with a little yellow and sometimes a bit of another color. Nothing is ever "white" or "black" to me anymore either, there is always a reflected color or a texture of some sort which catches the light from the surrounding sources.



            Edit:
            After further consideration I am inclined to say the question posted here is backwards. We actually discern many more separate colors in combination and at the same time than we do sounds. Look around and you will see a plethora of color combinations. We are actually perceiving many billions of separate photons coming from many billions of separate locations in our field of view. In contrast, listening to so many separate sounds would overwhelm our ears and perception of the sounds to the point of hearing only discord, static, or hissing like noises that have no meaning. It is only the combination of very few separate noises which can be discerned.







            share|cite|improve this answer














            share|cite|improve this answer



            share|cite|improve this answer








            edited 9 hours ago

























            answered yesterday









            takintoolong

            1093




            1093












            • You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
              – Kaz
              2 hours ago


















            • You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
              – Kaz
              2 hours ago
















            You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
            – Kaz
            2 hours ago




            You cannot distinguish a color that is a mixture of two or more frequencies of light from a color that is a pure frequency. Such a green still looks like it has yellow and blue even though it doesn't.
            – Kaz
            2 hours ago





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