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How does a violin reproduce overtones? - Theorizing a model


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1 hour ago, ctanzio said:

I suspect this is due to a certain amount of "noise" the bow hairs feed into string during the release in the catch and release cycle. I can hear the low level scratching of the bow when I play if I focus on that.

 

1 hour ago, Peter K-G said:

This is the general explenation I have got so far yes.

I think it's a combination of that and bridge rocking (like when you tap the bridge)

In any case, my view is that their relative Hz and db strength gives the violin its fundamental base sound, mostly to G & D strings.

I find I can hear their "chord" when playing (ignore the word chord, it's not what I mean)

Plucked => No bowhair noise :ph34r:

(ps. A0 is not split, when plucked, B0 is not present)

G-Pizz.thumb.JPG.c9c20802e90c4ab58741afa1542ed9ca.JPG

 

 

 

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1 hour ago, Andreas Preuss said:

@Peter K-G

If your point is that the first harmonic (overtone) is stronger than the fundamental frequency, this might come already from the string. (I think low piano strings work actually like that) 

Physics people here can certainly give an answer on that.

 

 

1 hour ago, Peter K-G said:

Not my point, that is the case with violins open G, the second harmonic is stronger at a certain distance from the mic and what type of mic is used. Violins are weak at 194 Hz

One more before Don wakes up...

The point is the orange boxes - fundamental low body modes shows up on spectrum

 

 

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1 hour ago, Andreas Preuss said:

@Peter K-G

If your point is that the first harmonic (overtone) is stronger than the fundamental frequency, this might come already from the string. (I think low piano strings work actually like that

Physics people here can certainly give an answer on that.

 

Indeed they do.

The "effect" is more noticeable close to the piano.  Over time lots of ideas were tried to fix this but none took. 

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25 minutes ago, ctanzio said:

It does sound strong for a good part of the population because of the ability of the brain to "hear" a tone which is the lowest frequency that is common to all the overtones. But not everyone can fill in a completely missing or weak fundamental. I have wondered if that could be a reason some people think certain tones on a violin are weak while other people think they are fine

That is indeed the case, without any doubt.

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7 minutes ago, Peter K-G said:

One more before Don wakes up...

I've been awake for a couple of hours now... refining F-holes and re-assembling a carpet cleaner.  

I don't have anything that I feel adds much to the conversation, other than: do the response plots include the start of the bow movment, or the initial pluck, or is that cropped out to just get steady-state response?

I have a lot to do for the next few days, so you all carry on.

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On 5/24/2021 at 3:08 PM, jezzupe said:

it creates an individual signature based on that particular violins shape, size, weight, elasticity {and other things} no other "flaps in the wind" quite like it, they will all be similar,{meaning you or anyone will be able to tell they are hearing a bowed instrument called a violin} some virtually identical , but no two will be the same.

 

 

It is interesting to consider what about the sound we hear tells us that it is from a violin.  It is easy to tell often that synthesized "violin" sound is supposed to sound like a violin but is recognizable as fake.  When we hear recorded sound, from LP, tape, or CD, we usually easily identify it as a recorded violin sound.  What is it that we recognize?  Frequencies seem to be important but recorded sound from an LP lacks much of the frequency spectrum.  Back in the years when high fidelity pretty much meant LP (say in the 1970's, pre CD) the high end audio people used to say that frequencies above 20000 Hz, though mostly inaudible to the human ear, had an effect on the quality of reproduced sound at audible frequencies.

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34 minutes ago, ctanzio said:

This is a specific example of the resonator model in action.

The G string is vibrating strongly with a 196Hz fundamental.

But the first major mode of the violin, A0 around 262Hz or a C, also known as the Helmholtz frequency, does not respond strongly to the G string's fundamental because the fundamental of the G (196Hz) and the natural frequency of A0 (~262Hz) are so far apart.

The air inside the violin is vibrating at 196Hz, just not very strongly compared to the other overtones of the G string.

It does sound strong for a good part of the population because of the ability of the brain to "hear" a tone which is the lowest frequency that is common to all the overtones. But not everyone can fill in a completely missing or weak fundamental. I have wondered if that could be a reason some people think certain tones on a violin are weak while other people think they are fine. 

Do we learn how to fool our own brain?

 

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On 5/24/2021 at 3:08 PM, jezzupe said:

The violin..........creates an individual signature based on that particular violins shape, size, weight, elasticity {and other things} no other "flaps in the wind" quite like it, they will all be similar,{meaning you or anyone will be able to tell they are hearing a bowed instrument called a violin} some virtually identical , but no two will be the same.........

[Emphasis above mine.]  Jezzupe "said a mouthful" right at the beginning of the thread, and it hasn't been examined nearly enough in this thread.  IMHO, "the beginning of wisdom" with respect to violin psychoacoustics is contained in the above quote.  How the sonic data that's being displayed and examined here is physically acquired and then examined by the brain, to tell us "violin", instead of any other bowed chordophone, is fundamental to figuring out what part of the sound generated by the violin is important to our research.  My SWAG is that some crucial frequency bands have been ignored, while some others have been overemphasized.  There will also be relationships between different signals, which will have been missed.  Perhaps a signal will have to be synthesized superimposing a tone at a time until a sample of listeners agree  on "violin", to sort out most of it.

How do we know that we are hearing a "violin"?  Does it depend on the spectrum of the first one that we ever knowingly heard played?  :)

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10 minutes ago, Violadamore said:

[Emphasis above mine.]  Jezzupe "said a mouthful" right at the beginning of the thread, and it hasn't been examined nearly enough in this thread.  IMHO, "the beginning of wisdom" with respect to violin psychoacoustics is contained in the above quote. 

1. How the sonic data that's being displayed and examined here is physically acquired and then examined by the brain, to tell us "violin", instead of any other bowed chordophone, is fundamental to figuring out what part of the sound generated by the violin is important to our research. 

2. My SWAG is that some crucial frequency bands have been ignored, while some others have been overemphasized.

3. How do we know that we are hearing a "violin"?  Does it depend on the spectrum of the first one that we ever knowingly heard played?  :)

1. I do not think that's the case at all.

2. It doesn't matter.

3. No.

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13 minutes ago, Violadamore said:

[Emphasis above mine.]  Jezzupe "said a mouthful" right at the beginning of the thread, and it hasn't been examined nearly enough in this thread.  IMHO, "the beginning of wisdom" with respect to violin psychoacoustics is contained in the above quote.  How the sonic data that's being displayed and examined here is physically acquired and then examined by the brain, to tell us "violin", instead of any other bowed chordophone, is fundamental to figuring out what part of the sound generated by the violin is important to our research.  My SWAG is that some crucial frequency bands have been ignored, while some others have been overemphasized.  There will also be relationships between different signals, which will have been missed.  Perhaps a signal will have to be synthesized superimposing a tone at a time until a sample of listeners agree  on "violin", to sort out most of it.

How do we know that we are hearing a "violin"?  Does it depend on the spectrum of the first one that we ever knowingly heard played?  :)

Of course this leads to what I call the "dog whistle theory" or, are their frequencies outside of our range of hearing that even though we can't hear them, somehow effect the sound we perceive we hear when the "tone" of "that" instrument is heard?

 

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On 5/24/2021 at 9:23 AM, Andreas Preuss said:

 

(1) Or, if we excite the bridge with a sine wave generator, the body wouldn't add by itself any overtones. (Wondering if this is really correct)

 

I think this is correct.  Drive any linear system with a pure sine wave and the output will be a pure sine wave.  But unless I have missed something, In which case I will be violently flogged, what I believe is that much of the spectrum of overtones results from the fact that the violin is driven by a saw-tooth wave created by slip-stick friction of the bow with the string, and that drive spectrum of the saw-tooth is rich in higher frequency overtones.  See  https://en.wikipedia.org/wiki/Sawtooth_wave

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1 minute ago, Roger Hill said:

Drive any linear system with a pure sine wave and the output will be a pure sine wave

True.

However, the question is if the violin is linear within a wide enough range of inputs, be those sinusoidal. I don't think it is but I'll entertain arguments to the contrary.

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1 hour ago, gowan said:

It is interesting to consider what about the sound we hear tells us that it is from a violin.  It is easy to tell often that synthesized "violin" sound is supposed to sound like a violin but is recognizable as fake.  When we hear recorded sound, from LP, tape, or CD, we usually easily identify it as a recorded violin sound.  What is it that we recognize?  Frequencies seem to be important but recorded sound from an LP lacks much of the frequency spectrum.  Back in the years when high fidelity pretty much meant LP (say in the 1970's, pre CD) the high end audio people used to say that frequencies above 20000 Hz, though mostly inaudible to the human ear, had an effect on the quality of reproduced sound at audible frequencies.

And then there are the advanced "listeners" where we can start talking about distinguishing the smae note but one played on a viola vs a violin, 2 very similar instruments , yet somehow sophisticated listeners such as ourselves can generally tells when a note is generated from a viola vs a violin, even if the same note as the "color" is different. 

I think of frequency as a composite of layers and I find it fascinating how sensitive some of our ears can become at telling subtle differences in tone and that because of this we must understand that in this case when we look at the elephant that it actually may be a different animal from one person to another based on their individual sensory capabilities.

related to the synthesis of sound generation, I also think that is a good example, where in recording music, even a really good keyboard tone that sounds very close to a violin, yet can still be picked out as fake, once mixed into "the mix" with other instruments, suddenly the "fake" seems to fade away as it blends with everything else and suddenly it sound pretty "violiny/string section'y " and "passes" for most listeners ears, and of course this is why keyboards have become a staple in recording, much cheaper than hiring the orchestra and well "good enough" in most listeners ears.

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1 hour ago, jezzupe said:

Of course this leads to what I call the "dog whistle theory" or, are [there] frequencies outside of our range of hearing that even though we can't hear them, somehow [a]ffect the sound we perceive we hear when the "tone" of "that" instrument is heard?

 

I'm suspecting that, with anything concerning music, the brain's processing is intimately entangled with what we perceive.  Just as with the previous discussion of linearity, if the brain is introducing virtual nonlinear components while processing the already complicated output of the orgy of superposition occurring in and around a violin, the purity of the original signal would be overwritten in what we "hear".  In pulling the thing apart to examine the workings, let's remember that a violin's ultimate purpose is to make music with.  That in itself may strongly affect what listeners and players report. 

On the purely physical (as contrasted with "virtual") level, signals above our hearing range could be exercising some control over sound production at lower frequencies, as well, via superposition.  The ability to generate certain ultrasounds might also be diagnostic of conditions necessary for a particular sound produced at lower frequencies, also.  Toto, we aren't in sophomore physics any more.  :lol:

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14 minutes ago, Violadamore said:

I'm suspecting that, with anything concerning music, the brain's processing is intimately entangled with what we perceive.  Just as with the previous discussion of linearity, if the brain is introducing virtual nonlinear components while processing the already complicated output of the orgy of superposition occurring in and around a violin, the purity of the original signal would be overwritten.

On the purely physical (as contrasted with "virtual") level, signals above our hearing range could be exercising some control over sound production at lower frequencies, as well, via superposition..

Well I think of sound as potentially like dimensions where there the ones we know and interact with and there are the ones we don't yet still interact with, we just don't know what any of that does or means.

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8 minutes ago, Violadamore said:

If you keep him occupied, he's less disruptive.  :ph34r::lol:

That's what my history teacher said in between me forming alliances for the coup to overthrow the system, those kids had no idea how complex me selecting myself as their Doge was gonna be.:lol:

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On 5/25/2021 at 2:34 PM, Marty Kasprzyk said:

The violin body is not an amplifier--it is an energy transducer.  It converts the vibrating energy of the string into the vibrating energy of the violin's body, which converts this energy into the vibration of air which is sound.  Nothing is amplified--no additional energy is added.

A vibrating string produces nearly no sound because the narrow width of the string is too narrow to move much air.  The violin body merely adds more surface area to efficiently move air. 

All the original harmonics of the vibrating strings are converted into harmonics of the sound produced.  No new harmonics are produced.

Some of the string's harmonic energy conversions are more efficient than others due to the violin body's various resonance peaks and valleys. This makes the sound output of a note's harmonics louder or softer.

A note from a bowed note does have some non harmonic noise from various sticking and sliding of the bow hair on the string.  If you play a single note and do an Audacity plot you will see some random noise between the harmonic series.  For example if you play an A note with a frequency of 220hz, its next harmonic will be 440hz, and the next one 660 etc.  In between these peaks there will be many much lower random noise peaks between the 220 and 440 peaks etc.

But this noise is not created by the violin body--it is produced by the string/bow interaction.  The violin body merely converts this random string vibration energy into sound noise energy.  

I'm quite sure the noise between a note's harmonics are produced by the bow hair. Attached is a plot up to 8000Hz of a bowed violin open G string as a blue line.  Also plotted is an orange line showing the bowing of the violin bridge upper bass side edge which produces a "hissy" kind of white noise.  

The violin body/bridge filters the bow noise just like it filters the string harmonics of a note and the orange line of the bowed bridge edge follows the same envelope shape as the noise of the bowed note.

Also attached is the same plot going up to only 600Hz.  The A0 resonance peak (~280Hz) shows up as noise just like Peter had found.  All violins probably do the same thing.

 

Screen Shot 2021-05-27 at 1.42.40 PM.png

Screen Shot 2021-05-27 at 1.41.28 PM.png

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5 hours ago, sospiri said:

Do we learn how to fool our own brain?

 

I think so. I also think that our brain can fool us, since some of the "wiring" seems to be prioritized toward speech recognition, including speech recognition under challenging situations, as when combined with wind noise, echoes, or battle noise. Good communication under challenging circumstances would have had high survival value.

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Don,

Have you come up with any ideas on the just under 1000 Hz peak, that is anoyingly strong on some violins?

I get wolfs at B5 on two of mine, not to disturbing, but if bowed quickly it real wobbles.

On both it falls right between B1- and B1+ an octave above.

This is speculation, but maybe it has something to do with Hutchins humming tone that appears between B1- and B1+ (at their relative strength)

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41 minutes ago, David Burgess said:

I think so. I also think that our brain can fool us, since some of the "wiring" seems to be prioritized toward speech recognition, including speech recognition under challenging situations, as when combined with wind noise, echoes, or battle noise. Good communication under challenging circumstances would have had high survival value.

Is this what is happening with the G string first position notes? A weak signal is interpreted as a strong signal, but as a learned process, conditioned by familiarity with the instrument?

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