At http://headwize.com/projects/showfile.php?file=meier5_prj.htm
Jan Meier says this:
“Mechanical harmonic distortion in the inner ear: A pure 200 Hz sine wave not only makes the basillary membrane inside the ear vibrate at 200 Hz, but also at 400, 600, 800, 1000, 1200.... Hz. For sine waves between 200 and 3000 Hz these overtones have amplitudes of 33%, 13%, 6%, 4%, 2%, .... of the amplitude of the fundamental. Harmonic distortion in the inner-ear thus sums up to approximately 60%! Nonetheless, we only hear a pure sine-wave at the fundamental frequency since our brain has learned that this specific frequency spectrum belongs to a pure tone.”
This made me wonder if it was possible to create a waveform which would let us perceive only the fundamental, and if so what that waveform would look like?
Pete McK
Jan Meier says this:
“Mechanical harmonic distortion in the inner ear: A pure 200 Hz sine wave not only makes the basillary membrane inside the ear vibrate at 200 Hz, but also at 400, 600, 800, 1000, 1200.... Hz. For sine waves between 200 and 3000 Hz these overtones have amplitudes of 33%, 13%, 6%, 4%, 2%, .... of the amplitude of the fundamental. Harmonic distortion in the inner-ear thus sums up to approximately 60%! Nonetheless, we only hear a pure sine-wave at the fundamental frequency since our brain has learned that this specific frequency spectrum belongs to a pure tone.”
This made me wonder if it was possible to create a waveform which would let us perceive only the fundamental, and if so what that waveform would look like?
Pete McK
Re: Re: Ok...
The lens in your eye projects an image on your retina that is upside down. Your brain corrects this and you never notice. Special glasses can flip it right side up (everything looks upside down)
I think you'd hear the missing harmonics like they're there. I don't think that this is something we need to worry about for HiFi, but it could be a consideration for cochlear implants or a future technology with direct connections to the brain!
-Joe
PS- I wrote more, but "check message length" tells me that this is over 10,000 characters!
EDIT: I completely misread the message that popped up. It was a little on the long side, and I thought that since I was new I might have some sort of introductory message length limit. What I was saying, though, is that with a wave "negative" would just mean "out of phase". So yes- I think that it's reasonably possible, if you studied an ear enough, to create a waveform that would produce a single fundamental at a given point. Of course, IIRC, the ear is a complicated thing and the part that converts motion to nerve impulses is not a single point.
454Casull said:
The lens in your eye projects an image on your retina that is upside down. Your brain corrects this and you never notice. Special glasses can flip it right side up (everything looks upside down)
I think you'd hear the missing harmonics like they're there. I don't think that this is something we need to worry about for HiFi, but it could be a consideration for cochlear implants or a future technology with direct connections to the brain!
-Joe
PS- I wrote more, but "check message length" tells me that this is over 10,000 characters!
EDIT: I completely misread the message that popped up. It was a little on the long side, and I thought that since I was new I might have some sort of introductory message length limit. What I was saying, though, is that with a wave "negative" would just mean "out of phase". So yes- I think that it's reasonably possible, if you studied an ear enough, to create a waveform that would produce a single fundamental at a given point. Of course, IIRC, the ear is a complicated thing and the part that converts motion to nerve impulses is not a single point.
You create the harmonic overtones and this makes you hear the fundamental without it being played. That's how several of the bass enhancement products like MaxxBass and others create the audio illusion of bass frequencies with drivers that won't play those low frequencies. The problem is that since those low frequencies aren't really played, you can't feel them so it doesn't sound quite real.
too tricky
>then how about a waveform that would excite only the >fundamental?
That's a nice idea.
One has to think about the way sound excites the membrane of the ear. To greatly simplify things one can consider a string with fixed endpoints e.g. a guitar string. If you were able to deform the string in a perfect half wavelength shape then release it I believe you would have no harmonics. However, if you were to pluck it at a point you would get all sorts of travelling waves. Some of those travelling waves, however would superimpose on opposite travelling ones just right to cause standing waves i.e. resonance at various harmonics. These waves eventually die away due to internal losses e.g. friction.
So you could try two things: you could either try to stick somethings in your ear which only excites the 'fundamental' or you could try to supress the membrane from vibrating at harmonics. Perhaps this would be possible by playing tones at the harmonics which are '180 deg' out of phase with the 'fundamental', by this I mean that when the 'fundamental' is pressure maximum, the supression tone reaches pressure minimum. However this depends on exactly how sound pressure excites the tympanic membrane. You could have the opposite effect!
Once could easily do audio experiments to see if the brain filters this stuff out.
>then how about a waveform that would excite only the >fundamental?
That's a nice idea.
One has to think about the way sound excites the membrane of the ear. To greatly simplify things one can consider a string with fixed endpoints e.g. a guitar string. If you were able to deform the string in a perfect half wavelength shape then release it I believe you would have no harmonics. However, if you were to pluck it at a point you would get all sorts of travelling waves. Some of those travelling waves, however would superimpose on opposite travelling ones just right to cause standing waves i.e. resonance at various harmonics. These waves eventually die away due to internal losses e.g. friction.
So you could try two things: you could either try to stick somethings in your ear which only excites the 'fundamental' or you could try to supress the membrane from vibrating at harmonics. Perhaps this would be possible by playing tones at the harmonics which are '180 deg' out of phase with the 'fundamental', by this I mean that when the 'fundamental' is pressure maximum, the supression tone reaches pressure minimum. However this depends on exactly how sound pressure excites the tympanic membrane. You could have the opposite effect!
Once could easily do audio experiments to see if the brain filters this stuff out.
mikee12345 said:
Certainly! perception and reality can be rather different things.
I downloaded a 'sub harmonic synthesiser' that adds 'lower bass'.Infact,all it does is make sinewaves more like square!
Sinewaves that start to look like squares means that they have harmonics being added, specifically odd harmonics. If you add even harmonics the sine will start to look like traingle waves. Of course, for perfect square waves or triangles the harmonics need to have a specific level ratio to the carrier.
Jan Didden
I wonder.... if mechanical harmonic distortion in the inner ear @ pure 200 Hz sine wave not only makes the basillary membrane inside the ear vibrate at 200 Hz, but also at 400, 600, 800, 1000, 1200.... Hz with amplitudes of 33%, 13%, 6%, 4%, 2%, .... then what happens with 1kHz or 10kHz sine waves??? 10kHz would create overtones of 20, 30, 40 ,50, 60 kHz but ear or brain himself filters everything above let's say 20kHz. So there must be some major diference between low freq and high freq. Maybee that's the reason for us to hear much more details on high freq. sounds...
The ear and hearing
The ear and brain are amazing devices able to do things way beyond our own comprehension. That seems sort of ironic saying that the brain can do thinsg beyond our comprehension. anyways. In order for a tone to be created that would excite only the fundimental cillia in the ear we would need to figure out exactly what frequencys the other cillia are vibrating at, and the exact amplitude and phase. to do this i could only invisoin one thing. An MRI video of the cochlea structure undergoing the tone. If a MRI machine exists that could video the insides of the ear to a very very small scale and an ultra high sampling rate then it is possible to map the resonance of the structures to determine the exact frequency amplitude and phase to be canceled. once it is determined exactly what is vibrating in there how much and at what phase, we could simply play around with canceling it out with some sound of opposite phase, equal amplitude and frequency. Is it worth doing? no way. my ears hear just fine thank you. Very intersting idea though
The ear and brain are amazing devices able to do things way beyond our own comprehension. That seems sort of ironic saying that the brain can do thinsg beyond our comprehension. anyways. In order for a tone to be created that would excite only the fundimental cillia in the ear we would need to figure out exactly what frequencys the other cillia are vibrating at, and the exact amplitude and phase. to do this i could only invisoin one thing. An MRI video of the cochlea structure undergoing the tone. If a MRI machine exists that could video the insides of the ear to a very very small scale and an ultra high sampling rate then it is possible to map the resonance of the structures to determine the exact frequency amplitude and phase to be canceled. once it is determined exactly what is vibrating in there how much and at what phase, we could simply play around with canceling it out with some sound of opposite phase, equal amplitude and frequency. Is it worth doing? no way. my ears hear just fine thank you. Very intersting idea though
The ear
I think we ought to investigate more into the workings of the ear. Perhaps a thread should be created about sound localization and the workings of the ear/brain in sound perception. I dont know alot about it, but from what i do know. its some amazing stuff. The workings of the ear/ brain in sound localization are the essential key to finding better ways to produce true surround sound stereo systems and on the way to everyone's dream. Perfect audio reproduction.
today i would like to talk about reproduction...
sound reproduction that is
I think we ought to investigate more into the workings of the ear. Perhaps a thread should be created about sound localization and the workings of the ear/brain in sound perception. I dont know alot about it, but from what i do know. its some amazing stuff. The workings of the ear/ brain in sound localization are the essential key to finding better ways to produce true surround sound stereo systems and on the way to everyone's dream. Perfect audio reproduction.
today i would like to talk about reproduction...
sound reproduction that is
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