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Why don't humans perceive sound waves as twice the frequency they are?


Deriving the group velocity of a wave produced by some basic cosine waves with unequal amplitudesIs it possible to create an audible sound source in mid air by intersecting ultrasonic sound beams?Frequency of Sound WavesWhy do we hear the square of the wave?Pound-Drever-Hall frequency stabilisation techniqueCan you excite coupled pendula at the frequency difference?How are beats formed when frequencies combine?Sound waves: frequency, speed, and wavelengthMultivariable Chain-Rule in Wave-Energy EquationsMaximum of a sound wave






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








10












$begingroup$


I was reading about how at how acoustic beats work.



If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is
$$
beginalign
A
&= cosleft(2pi f_1xright) + cosleft(2pi f_2xright) \[10px]
&= 2cosleft(2pi , fracf_1-f_22,xright)cosleft(2pi , fracf_1+f_22 , xright) ,.
endalign
$$



According to "Beat (acoustics)", Wikipedia:




Because the human ear is not sensitive to the phase of a sound, only its amplitude or intensity, only the magnitude of the envelope is heard.




So obviously the beat frequency is twice the envelope (since you're squaring it) and you get $$f_textbeat = f_1-f_2$$and not half that.



Now consider a regular cosine wave $A = cosleft(2pi f_Tright)$ with frequency $f_T$. Taking the magnitude (as Wikipedia says, i.e. by squaring $A$) gives you an audible frequency of $2f_T$... so do people hear frequencies as twice what they are in their amplitude wave?




EDIT:
The answer is we DO perceive twice the frequency -- a sound wave that we define as having a frequency f will stimulate our ears with twice that frequency.




This frequency f is just a convenient name we give to the waves our machines make. This doesn't bother anyone as people can't hear in slow motion and i.e. count 200 'ticks' per second when playing a 100 Hz wave.










share|cite|improve this question











$endgroup$









  • 33




    $begingroup$
    If they did, how could you measure it?
    $endgroup$
    – immibis
    Jul 19 at 2:49






  • 17




    $begingroup$
    If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
    $endgroup$
    – Flater
    Jul 19 at 8:25






  • 6




    $begingroup$
    We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
    $endgroup$
    – OrangeDog
    Jul 19 at 10:32






  • 5




    $begingroup$
    @ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
    $endgroup$
    – TKK
    Jul 19 at 16:39

















10












$begingroup$


I was reading about how at how acoustic beats work.



If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is
$$
beginalign
A
&= cosleft(2pi f_1xright) + cosleft(2pi f_2xright) \[10px]
&= 2cosleft(2pi , fracf_1-f_22,xright)cosleft(2pi , fracf_1+f_22 , xright) ,.
endalign
$$



According to "Beat (acoustics)", Wikipedia:




Because the human ear is not sensitive to the phase of a sound, only its amplitude or intensity, only the magnitude of the envelope is heard.




So obviously the beat frequency is twice the envelope (since you're squaring it) and you get $$f_textbeat = f_1-f_2$$and not half that.



Now consider a regular cosine wave $A = cosleft(2pi f_Tright)$ with frequency $f_T$. Taking the magnitude (as Wikipedia says, i.e. by squaring $A$) gives you an audible frequency of $2f_T$... so do people hear frequencies as twice what they are in their amplitude wave?




EDIT:
The answer is we DO perceive twice the frequency -- a sound wave that we define as having a frequency f will stimulate our ears with twice that frequency.




This frequency f is just a convenient name we give to the waves our machines make. This doesn't bother anyone as people can't hear in slow motion and i.e. count 200 'ticks' per second when playing a 100 Hz wave.










share|cite|improve this question











$endgroup$









  • 33




    $begingroup$
    If they did, how could you measure it?
    $endgroup$
    – immibis
    Jul 19 at 2:49






  • 17




    $begingroup$
    If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
    $endgroup$
    – Flater
    Jul 19 at 8:25






  • 6




    $begingroup$
    We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
    $endgroup$
    – OrangeDog
    Jul 19 at 10:32






  • 5




    $begingroup$
    @ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
    $endgroup$
    – TKK
    Jul 19 at 16:39













10












10








10


5



$begingroup$


I was reading about how at how acoustic beats work.



If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is
$$
beginalign
A
&= cosleft(2pi f_1xright) + cosleft(2pi f_2xright) \[10px]
&= 2cosleft(2pi , fracf_1-f_22,xright)cosleft(2pi , fracf_1+f_22 , xright) ,.
endalign
$$



According to "Beat (acoustics)", Wikipedia:




Because the human ear is not sensitive to the phase of a sound, only its amplitude or intensity, only the magnitude of the envelope is heard.




So obviously the beat frequency is twice the envelope (since you're squaring it) and you get $$f_textbeat = f_1-f_2$$and not half that.



Now consider a regular cosine wave $A = cosleft(2pi f_Tright)$ with frequency $f_T$. Taking the magnitude (as Wikipedia says, i.e. by squaring $A$) gives you an audible frequency of $2f_T$... so do people hear frequencies as twice what they are in their amplitude wave?




EDIT:
The answer is we DO perceive twice the frequency -- a sound wave that we define as having a frequency f will stimulate our ears with twice that frequency.




This frequency f is just a convenient name we give to the waves our machines make. This doesn't bother anyone as people can't hear in slow motion and i.e. count 200 'ticks' per second when playing a 100 Hz wave.










share|cite|improve this question











$endgroup$




I was reading about how at how acoustic beats work.



If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is
$$
beginalign
A
&= cosleft(2pi f_1xright) + cosleft(2pi f_2xright) \[10px]
&= 2cosleft(2pi , fracf_1-f_22,xright)cosleft(2pi , fracf_1+f_22 , xright) ,.
endalign
$$



According to "Beat (acoustics)", Wikipedia:




Because the human ear is not sensitive to the phase of a sound, only its amplitude or intensity, only the magnitude of the envelope is heard.




So obviously the beat frequency is twice the envelope (since you're squaring it) and you get $$f_textbeat = f_1-f_2$$and not half that.



Now consider a regular cosine wave $A = cosleft(2pi f_Tright)$ with frequency $f_T$. Taking the magnitude (as Wikipedia says, i.e. by squaring $A$) gives you an audible frequency of $2f_T$... so do people hear frequencies as twice what they are in their amplitude wave?




EDIT:
The answer is we DO perceive twice the frequency -- a sound wave that we define as having a frequency f will stimulate our ears with twice that frequency.




This frequency f is just a convenient name we give to the waves our machines make. This doesn't bother anyone as people can't hear in slow motion and i.e. count 200 'ticks' per second when playing a 100 Hz wave.







waves acoustics frequency perception






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jul 24 at 0:59







Mondo Duke

















asked Jul 18 at 18:26









Mondo DukeMondo Duke

651 silver badge6 bronze badges




651 silver badge6 bronze badges










  • 33




    $begingroup$
    If they did, how could you measure it?
    $endgroup$
    – immibis
    Jul 19 at 2:49






  • 17




    $begingroup$
    If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
    $endgroup$
    – Flater
    Jul 19 at 8:25






  • 6




    $begingroup$
    We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
    $endgroup$
    – OrangeDog
    Jul 19 at 10:32






  • 5




    $begingroup$
    @ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
    $endgroup$
    – TKK
    Jul 19 at 16:39












  • 33




    $begingroup$
    If they did, how could you measure it?
    $endgroup$
    – immibis
    Jul 19 at 2:49






  • 17




    $begingroup$
    If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
    $endgroup$
    – Flater
    Jul 19 at 8:25






  • 6




    $begingroup$
    We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
    $endgroup$
    – OrangeDog
    Jul 19 at 10:32






  • 5




    $begingroup$
    @ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
    $endgroup$
    – TKK
    Jul 19 at 16:39







33




33




$begingroup$
If they did, how could you measure it?
$endgroup$
– immibis
Jul 19 at 2:49




$begingroup$
If they did, how could you measure it?
$endgroup$
– immibis
Jul 19 at 2:49




17




17




$begingroup$
If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
$endgroup$
– Flater
Jul 19 at 8:25




$begingroup$
If humans always perceived them as double; they would never figure out that they're hearing double of what they should hear. This is the same principle like how our eyees work like a camera obscura (which inherently inverts the image) but humans automatically correct their perception so the world doesn't look upside down.
$endgroup$
– Flater
Jul 19 at 8:25




6




6




$begingroup$
We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
$endgroup$
– OrangeDog
Jul 19 at 10:32




$begingroup$
We don't "hear" frequencies. We perceive something close to a logarithmic fourier transform of what's moving in our ears, further processed and interpreted by our brains.
$endgroup$
– OrangeDog
Jul 19 at 10:32




5




5




$begingroup$
@ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
$endgroup$
– TKK
Jul 19 at 16:39




$begingroup$
@ThePhoton Probably the similarity of this question to the age old, "Is your blue the same as my blue?"
$endgroup$
– TKK
Jul 19 at 16:39










5 Answers
5






active

oldest

votes


















1












$begingroup$

Your intuition is right. It seems you might have missed this statement in the same Wikipedia article which confirms what you're asking:




Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is: $$f_textbeat = f_1-f_2$$




Basically the wavelength of a beat, as far as hearing is concerned, is the duration between successive amplitude maxima, and not the abstract modulating cosine wave which has twice that length.






share|cite|improve this answer









$endgroup$






















    37












    $begingroup$

    Humans hear the correct perceptive signal for a sound wave of that frequency.



    We really can't say much more than that. The psychology of acoustics are very complicated and could fill volumes.



    It's closer to say we have cells which act resonant at a specific frequency. Our brain identifies which cells are resonating at any point in time, and constructs the signal from that. Our brains receive information that cell A or cell B is signalling. The association between those neural signals and frequencies is a learned response that we pick up early on, as an infant or perhaps even in the womb.






    share|cite|improve this answer









    $endgroup$














    • $begingroup$
      Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
      $endgroup$
      – Pieter
      Jul 18 at 18:53











    • $begingroup$
      Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
      $endgroup$
      – Mondo Duke
      Jul 18 at 19:39







    • 1




      $begingroup$
      @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
      $endgroup$
      – Pieter
      Jul 18 at 19:55






    • 16




      $begingroup$
      We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
      $endgroup$
      – Cort Ammon
      Jul 18 at 22:37






    • 2




      $begingroup$
      Aren't beats different than tones though? Isn't this what the OP is asking about?
      $endgroup$
      – Aaron Stevens
      Jul 19 at 0:17


















    24












    $begingroup$


    So obviously the audible frequency is twice the envelope




    Sorry, that's wrong. If you play two tones (say 440 Hz and 267 Hz), you simply hear two tones at two different frequencies and you have two excitations at different spots on the basilar membrane and two different sets of nerves firing. You don't hear the envelope at all, they just sound like two steady-state tones.



    "Beats" only happen when you have two frequencies that are VERY close together, say 237 Hz and 238 Hz. In this case, your ear can't resolve the frequency difference anymore but you hear a single tone at 237.5 Hz that's amplitude modulated at 1 Hz.




    Taking the magnitude (as wikipedia says, i.e. by squaring A) gives you
    an audible frequency of 2fT




    No. You can square the amplitude to estimate power or energy but there is no mechanism that would square the actual waveform. If you play 100 Hz, you hear 100 Hz, that's all there is to it.






    share|cite|improve this answer











    $endgroup$










    • 2




      $begingroup$
      Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
      $endgroup$
      – Vaelus
      Jul 19 at 14:50










    • $begingroup$
      That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
      $endgroup$
      – knzhou
      Jul 20 at 14:22


















    10












    $begingroup$

    The human perception of a wave at frequency $f$ is the human perception of a wave at frequency $f$. There is no "objective" qualia for frequency $f$ other than what people perceive, so it's nonsensical to ask whether people, when they hear $f$, perceive $2f$; there is no meaning to "perceive $2f$" other than "experience the qualia associated with $2f$", and clearly when someone hears $f$, they experience that qualia associated with $f$, not $2f$.



    The human ear basically is a device for detecting components of the Fourier transform of sound. The reason that $f_2-f_1$ dominates with beats is that if $f_2+f_1$ is high enough, then the $f_2-f_1$ component will not be significantly affected by multiplying by a $f_2+f_1$ wave.






    share|cite|improve this answer









    $endgroup$






















      3












      $begingroup$

      The human ear is only sensitive to the amplitude in the sense that you can't tell apart $sin(t)$ and $sin(t+phi)$. It doesn't mean you cannot tell apart $sin(t)$ and $sin^2(t)$: the latter will be heard as twice the frequency at half the volume.






      share|cite|improve this answer









      $endgroup$










      • 1




        $begingroup$
        @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
        $endgroup$
        – Andreas Blass
        Jul 21 at 0:11













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      5 Answers
      5






      active

      oldest

      votes








      5 Answers
      5






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      1












      $begingroup$

      Your intuition is right. It seems you might have missed this statement in the same Wikipedia article which confirms what you're asking:




      Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is: $$f_textbeat = f_1-f_2$$




      Basically the wavelength of a beat, as far as hearing is concerned, is the duration between successive amplitude maxima, and not the abstract modulating cosine wave which has twice that length.






      share|cite|improve this answer









      $endgroup$



















        1












        $begingroup$

        Your intuition is right. It seems you might have missed this statement in the same Wikipedia article which confirms what you're asking:




        Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is: $$f_textbeat = f_1-f_2$$




        Basically the wavelength of a beat, as far as hearing is concerned, is the duration between successive amplitude maxima, and not the abstract modulating cosine wave which has twice that length.






        share|cite|improve this answer









        $endgroup$

















          1












          1








          1





          $begingroup$

          Your intuition is right. It seems you might have missed this statement in the same Wikipedia article which confirms what you're asking:




          Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is: $$f_textbeat = f_1-f_2$$




          Basically the wavelength of a beat, as far as hearing is concerned, is the duration between successive amplitude maxima, and not the abstract modulating cosine wave which has twice that length.






          share|cite|improve this answer









          $endgroup$



          Your intuition is right. It seems you might have missed this statement in the same Wikipedia article which confirms what you're asking:




          Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is: $$f_textbeat = f_1-f_2$$




          Basically the wavelength of a beat, as far as hearing is concerned, is the duration between successive amplitude maxima, and not the abstract modulating cosine wave which has twice that length.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jul 21 at 5:44









          KazKaz

          2,59511 silver badges16 bronze badges




          2,59511 silver badges16 bronze badges


























              37












              $begingroup$

              Humans hear the correct perceptive signal for a sound wave of that frequency.



              We really can't say much more than that. The psychology of acoustics are very complicated and could fill volumes.



              It's closer to say we have cells which act resonant at a specific frequency. Our brain identifies which cells are resonating at any point in time, and constructs the signal from that. Our brains receive information that cell A or cell B is signalling. The association between those neural signals and frequencies is a learned response that we pick up early on, as an infant or perhaps even in the womb.






              share|cite|improve this answer









              $endgroup$














              • $begingroup$
                Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
                $endgroup$
                – Pieter
                Jul 18 at 18:53











              • $begingroup$
                Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
                $endgroup$
                – Mondo Duke
                Jul 18 at 19:39







              • 1




                $begingroup$
                @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
                $endgroup$
                – Pieter
                Jul 18 at 19:55






              • 16




                $begingroup$
                We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
                $endgroup$
                – Cort Ammon
                Jul 18 at 22:37






              • 2




                $begingroup$
                Aren't beats different than tones though? Isn't this what the OP is asking about?
                $endgroup$
                – Aaron Stevens
                Jul 19 at 0:17















              37












              $begingroup$

              Humans hear the correct perceptive signal for a sound wave of that frequency.



              We really can't say much more than that. The psychology of acoustics are very complicated and could fill volumes.



              It's closer to say we have cells which act resonant at a specific frequency. Our brain identifies which cells are resonating at any point in time, and constructs the signal from that. Our brains receive information that cell A or cell B is signalling. The association between those neural signals and frequencies is a learned response that we pick up early on, as an infant or perhaps even in the womb.






              share|cite|improve this answer









              $endgroup$














              • $begingroup$
                Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
                $endgroup$
                – Pieter
                Jul 18 at 18:53











              • $begingroup$
                Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
                $endgroup$
                – Mondo Duke
                Jul 18 at 19:39







              • 1




                $begingroup$
                @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
                $endgroup$
                – Pieter
                Jul 18 at 19:55






              • 16




                $begingroup$
                We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
                $endgroup$
                – Cort Ammon
                Jul 18 at 22:37






              • 2




                $begingroup$
                Aren't beats different than tones though? Isn't this what the OP is asking about?
                $endgroup$
                – Aaron Stevens
                Jul 19 at 0:17













              37












              37








              37





              $begingroup$

              Humans hear the correct perceptive signal for a sound wave of that frequency.



              We really can't say much more than that. The psychology of acoustics are very complicated and could fill volumes.



              It's closer to say we have cells which act resonant at a specific frequency. Our brain identifies which cells are resonating at any point in time, and constructs the signal from that. Our brains receive information that cell A or cell B is signalling. The association between those neural signals and frequencies is a learned response that we pick up early on, as an infant or perhaps even in the womb.






              share|cite|improve this answer









              $endgroup$



              Humans hear the correct perceptive signal for a sound wave of that frequency.



              We really can't say much more than that. The psychology of acoustics are very complicated and could fill volumes.



              It's closer to say we have cells which act resonant at a specific frequency. Our brain identifies which cells are resonating at any point in time, and constructs the signal from that. Our brains receive information that cell A or cell B is signalling. The association between those neural signals and frequencies is a learned response that we pick up early on, as an infant or perhaps even in the womb.







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered Jul 18 at 18:44









              Cort AmmonCort Ammon

              26.8k4 gold badges58 silver badges91 bronze badges




              26.8k4 gold badges58 silver badges91 bronze badges














              • $begingroup$
                Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
                $endgroup$
                – Pieter
                Jul 18 at 18:53











              • $begingroup$
                Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
                $endgroup$
                – Mondo Duke
                Jul 18 at 19:39







              • 1




                $begingroup$
                @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
                $endgroup$
                – Pieter
                Jul 18 at 19:55






              • 16




                $begingroup$
                We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
                $endgroup$
                – Cort Ammon
                Jul 18 at 22:37






              • 2




                $begingroup$
                Aren't beats different than tones though? Isn't this what the OP is asking about?
                $endgroup$
                – Aaron Stevens
                Jul 19 at 0:17
















              • $begingroup$
                Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
                $endgroup$
                – Pieter
                Jul 18 at 18:53











              • $begingroup$
                Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
                $endgroup$
                – Mondo Duke
                Jul 18 at 19:39







              • 1




                $begingroup$
                @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
                $endgroup$
                – Pieter
                Jul 18 at 19:55






              • 16




                $begingroup$
                We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
                $endgroup$
                – Cort Ammon
                Jul 18 at 22:37






              • 2




                $begingroup$
                Aren't beats different than tones though? Isn't this what the OP is asking about?
                $endgroup$
                – Aaron Stevens
                Jul 19 at 0:17















              $begingroup$
              Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
              $endgroup$
              – Pieter
              Jul 18 at 18:53





              $begingroup$
              Yes. The frequencies are mapped to different distances in the cochlea. Only for low frequencies is there a relation between the action potentials and the phase of the wave. This plays a role in binaural direction sensing.
              $endgroup$
              – Pieter
              Jul 18 at 18:53













              $begingroup$
              Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
              $endgroup$
              – Mondo Duke
              Jul 18 at 19:39





              $begingroup$
              Ok now I understand that sound is really subjective to how our cells perceive it. I'm still a bit confused -- I know humans hear sound waves when there are compressions and expansions in our ears, and we can't tell the difference between the two. A sound wave of frequency 1 wave per second is defined as looking like a peak/trough sine wave (or a compression and then an expansion in a second). But since we can't tell the difference between compression and expansion, won't our ears feel this frequency "1" wave as happening twice per second (i.e. an actual frequency of "2" signals per second)
              $endgroup$
              – Mondo Duke
              Jul 18 at 19:39





              1




              1




              $begingroup$
              @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
              $endgroup$
              – Pieter
              Jul 18 at 19:55




              $begingroup$
              @MondoDuke A sine wave of 100 Hz causes movements of the basilar membrane at a different position than a sine wave of 200 Hz. Different hair cells are stimulated, different "threads" in the auditory nerve start firing. (But if you want to experience something weird, listen with headphones to binaural beats.)
              $endgroup$
              – Pieter
              Jul 18 at 19:55




              16




              16




              $begingroup$
              We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
              $endgroup$
              – Cort Ammon
              Jul 18 at 22:37




              $begingroup$
              We don't "sense" every cycle in the way you're thinking about it. A nerve fiber which is used in detecting 2kHz does not fire twice as fast as a nerve fiber which is used to detect 1kHz. Both fibers transmit something more akin to "here's how much power there is where my cells are at," and the cells are structured to do a fourier transform of sorts.
              $endgroup$
              – Cort Ammon
              Jul 18 at 22:37




              2




              2




              $begingroup$
              Aren't beats different than tones though? Isn't this what the OP is asking about?
              $endgroup$
              – Aaron Stevens
              Jul 19 at 0:17




              $begingroup$
              Aren't beats different than tones though? Isn't this what the OP is asking about?
              $endgroup$
              – Aaron Stevens
              Jul 19 at 0:17











              24












              $begingroup$


              So obviously the audible frequency is twice the envelope




              Sorry, that's wrong. If you play two tones (say 440 Hz and 267 Hz), you simply hear two tones at two different frequencies and you have two excitations at different spots on the basilar membrane and two different sets of nerves firing. You don't hear the envelope at all, they just sound like two steady-state tones.



              "Beats" only happen when you have two frequencies that are VERY close together, say 237 Hz and 238 Hz. In this case, your ear can't resolve the frequency difference anymore but you hear a single tone at 237.5 Hz that's amplitude modulated at 1 Hz.




              Taking the magnitude (as wikipedia says, i.e. by squaring A) gives you
              an audible frequency of 2fT




              No. You can square the amplitude to estimate power or energy but there is no mechanism that would square the actual waveform. If you play 100 Hz, you hear 100 Hz, that's all there is to it.






              share|cite|improve this answer











              $endgroup$










              • 2




                $begingroup$
                Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
                $endgroup$
                – Vaelus
                Jul 19 at 14:50










              • $begingroup$
                That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
                $endgroup$
                – knzhou
                Jul 20 at 14:22















              24












              $begingroup$


              So obviously the audible frequency is twice the envelope




              Sorry, that's wrong. If you play two tones (say 440 Hz and 267 Hz), you simply hear two tones at two different frequencies and you have two excitations at different spots on the basilar membrane and two different sets of nerves firing. You don't hear the envelope at all, they just sound like two steady-state tones.



              "Beats" only happen when you have two frequencies that are VERY close together, say 237 Hz and 238 Hz. In this case, your ear can't resolve the frequency difference anymore but you hear a single tone at 237.5 Hz that's amplitude modulated at 1 Hz.




              Taking the magnitude (as wikipedia says, i.e. by squaring A) gives you
              an audible frequency of 2fT




              No. You can square the amplitude to estimate power or energy but there is no mechanism that would square the actual waveform. If you play 100 Hz, you hear 100 Hz, that's all there is to it.






              share|cite|improve this answer











              $endgroup$










              • 2




                $begingroup$
                Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
                $endgroup$
                – Vaelus
                Jul 19 at 14:50










              • $begingroup$
                That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
                $endgroup$
                – knzhou
                Jul 20 at 14:22













              24












              24








              24





              $begingroup$


              So obviously the audible frequency is twice the envelope




              Sorry, that's wrong. If you play two tones (say 440 Hz and 267 Hz), you simply hear two tones at two different frequencies and you have two excitations at different spots on the basilar membrane and two different sets of nerves firing. You don't hear the envelope at all, they just sound like two steady-state tones.



              "Beats" only happen when you have two frequencies that are VERY close together, say 237 Hz and 238 Hz. In this case, your ear can't resolve the frequency difference anymore but you hear a single tone at 237.5 Hz that's amplitude modulated at 1 Hz.




              Taking the magnitude (as wikipedia says, i.e. by squaring A) gives you
              an audible frequency of 2fT




              No. You can square the amplitude to estimate power or energy but there is no mechanism that would square the actual waveform. If you play 100 Hz, you hear 100 Hz, that's all there is to it.






              share|cite|improve this answer











              $endgroup$




              So obviously the audible frequency is twice the envelope




              Sorry, that's wrong. If you play two tones (say 440 Hz and 267 Hz), you simply hear two tones at two different frequencies and you have two excitations at different spots on the basilar membrane and two different sets of nerves firing. You don't hear the envelope at all, they just sound like two steady-state tones.



              "Beats" only happen when you have two frequencies that are VERY close together, say 237 Hz and 238 Hz. In this case, your ear can't resolve the frequency difference anymore but you hear a single tone at 237.5 Hz that's amplitude modulated at 1 Hz.




              Taking the magnitude (as wikipedia says, i.e. by squaring A) gives you
              an audible frequency of 2fT




              No. You can square the amplitude to estimate power or energy but there is no mechanism that would square the actual waveform. If you play 100 Hz, you hear 100 Hz, that's all there is to it.







              share|cite|improve this answer














              share|cite|improve this answer



              share|cite|improve this answer








              edited Jul 20 at 13:40









              Loong

              1,91013 silver badges23 bronze badges




              1,91013 silver badges23 bronze badges










              answered Jul 18 at 22:52









              HilmarHilmar

              1,2546 silver badges8 bronze badges




              1,2546 silver badges8 bronze badges










              • 2




                $begingroup$
                Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
                $endgroup$
                – Vaelus
                Jul 19 at 14:50










              • $begingroup$
                That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
                $endgroup$
                – knzhou
                Jul 20 at 14:22












              • 2




                $begingroup$
                Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
                $endgroup$
                – Vaelus
                Jul 19 at 14:50










              • $begingroup$
                That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
                $endgroup$
                – knzhou
                Jul 20 at 14:22







              2




              2




              $begingroup$
              Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
              $endgroup$
              – Vaelus
              Jul 19 at 14:50




              $begingroup$
              Although, the apparent sine waves traced by the envelope have 1/2 Hz. Example
              $endgroup$
              – Vaelus
              Jul 19 at 14:50












              $begingroup$
              That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
              $endgroup$
              – knzhou
              Jul 20 at 14:22




              $begingroup$
              That's too strong of a statement to make. There's another theory of hearing, the temporal theory, where the neurons really do record the frequency directly. I'm under the impression that neither the temporal theory nor yours (called the "place" theory) can explain all observations; the real, messy process of hearing might use both.
              $endgroup$
              – knzhou
              Jul 20 at 14:22











              10












              $begingroup$

              The human perception of a wave at frequency $f$ is the human perception of a wave at frequency $f$. There is no "objective" qualia for frequency $f$ other than what people perceive, so it's nonsensical to ask whether people, when they hear $f$, perceive $2f$; there is no meaning to "perceive $2f$" other than "experience the qualia associated with $2f$", and clearly when someone hears $f$, they experience that qualia associated with $f$, not $2f$.



              The human ear basically is a device for detecting components of the Fourier transform of sound. The reason that $f_2-f_1$ dominates with beats is that if $f_2+f_1$ is high enough, then the $f_2-f_1$ component will not be significantly affected by multiplying by a $f_2+f_1$ wave.






              share|cite|improve this answer









              $endgroup$



















                10












                $begingroup$

                The human perception of a wave at frequency $f$ is the human perception of a wave at frequency $f$. There is no "objective" qualia for frequency $f$ other than what people perceive, so it's nonsensical to ask whether people, when they hear $f$, perceive $2f$; there is no meaning to "perceive $2f$" other than "experience the qualia associated with $2f$", and clearly when someone hears $f$, they experience that qualia associated with $f$, not $2f$.



                The human ear basically is a device for detecting components of the Fourier transform of sound. The reason that $f_2-f_1$ dominates with beats is that if $f_2+f_1$ is high enough, then the $f_2-f_1$ component will not be significantly affected by multiplying by a $f_2+f_1$ wave.






                share|cite|improve this answer









                $endgroup$

















                  10












                  10








                  10





                  $begingroup$

                  The human perception of a wave at frequency $f$ is the human perception of a wave at frequency $f$. There is no "objective" qualia for frequency $f$ other than what people perceive, so it's nonsensical to ask whether people, when they hear $f$, perceive $2f$; there is no meaning to "perceive $2f$" other than "experience the qualia associated with $2f$", and clearly when someone hears $f$, they experience that qualia associated with $f$, not $2f$.



                  The human ear basically is a device for detecting components of the Fourier transform of sound. The reason that $f_2-f_1$ dominates with beats is that if $f_2+f_1$ is high enough, then the $f_2-f_1$ component will not be significantly affected by multiplying by a $f_2+f_1$ wave.






                  share|cite|improve this answer









                  $endgroup$



                  The human perception of a wave at frequency $f$ is the human perception of a wave at frequency $f$. There is no "objective" qualia for frequency $f$ other than what people perceive, so it's nonsensical to ask whether people, when they hear $f$, perceive $2f$; there is no meaning to "perceive $2f$" other than "experience the qualia associated with $2f$", and clearly when someone hears $f$, they experience that qualia associated with $f$, not $2f$.



                  The human ear basically is a device for detecting components of the Fourier transform of sound. The reason that $f_2-f_1$ dominates with beats is that if $f_2+f_1$ is high enough, then the $f_2-f_1$ component will not be significantly affected by multiplying by a $f_2+f_1$ wave.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jul 19 at 17:47









                  AcccumulationAcccumulation

                  4,2117 silver badges17 bronze badges




                  4,2117 silver badges17 bronze badges
























                      3












                      $begingroup$

                      The human ear is only sensitive to the amplitude in the sense that you can't tell apart $sin(t)$ and $sin(t+phi)$. It doesn't mean you cannot tell apart $sin(t)$ and $sin^2(t)$: the latter will be heard as twice the frequency at half the volume.






                      share|cite|improve this answer









                      $endgroup$










                      • 1




                        $begingroup$
                        @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                        $endgroup$
                        – Andreas Blass
                        Jul 21 at 0:11















                      3












                      $begingroup$

                      The human ear is only sensitive to the amplitude in the sense that you can't tell apart $sin(t)$ and $sin(t+phi)$. It doesn't mean you cannot tell apart $sin(t)$ and $sin^2(t)$: the latter will be heard as twice the frequency at half the volume.






                      share|cite|improve this answer









                      $endgroup$










                      • 1




                        $begingroup$
                        @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                        $endgroup$
                        – Andreas Blass
                        Jul 21 at 0:11













                      3












                      3








                      3





                      $begingroup$

                      The human ear is only sensitive to the amplitude in the sense that you can't tell apart $sin(t)$ and $sin(t+phi)$. It doesn't mean you cannot tell apart $sin(t)$ and $sin^2(t)$: the latter will be heard as twice the frequency at half the volume.






                      share|cite|improve this answer









                      $endgroup$



                      The human ear is only sensitive to the amplitude in the sense that you can't tell apart $sin(t)$ and $sin(t+phi)$. It doesn't mean you cannot tell apart $sin(t)$ and $sin^2(t)$: the latter will be heard as twice the frequency at half the volume.







                      share|cite|improve this answer












                      share|cite|improve this answer



                      share|cite|improve this answer










                      answered Jul 19 at 9:35









                      Dmitry GrigoryevDmitry Grigoryev

                      3,0741 gold badge8 silver badges25 bronze badges




                      3,0741 gold badge8 silver badges25 bronze badges










                      • 1




                        $begingroup$
                        @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                        $endgroup$
                        – Andreas Blass
                        Jul 21 at 0:11












                      • 1




                        $begingroup$
                        @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                        $endgroup$
                        – Andreas Blass
                        Jul 21 at 0:11







                      1




                      1




                      $begingroup$
                      @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                      $endgroup$
                      – Andreas Blass
                      Jul 21 at 0:11




                      $begingroup$
                      @Jasper I think he meant sensitive to amplitude and frequency but not to phase (as the rest of the sentence suggests).
                      $endgroup$
                      – Andreas Blass
                      Jul 21 at 0:11

















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