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pooispoois

Physics of sound production - does the bow stick actually make a difference?

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Hello! I have come from a long hiatus to try and understand one particular component of sound production: does the bow stick itself actually have any impact on sound?

 

The question seems to be at least somewhat controversial, given that lots of bow marketing is somehow based on the effect the bow has on sound. Yet to me, taking into account my simplistic understanding on how sound is produced on the violin, would seem to dictate that the stick itself would have no direct effect at all. The resonating body is the violin; and the vibration is produced by a three-way interaction between strings, bowhair and rosin. Given this, how could the stick ever impact sound (other than the indirect impact of regulating the tension of the bowhair)?

 

Regarding sound and sound only, does it really matter if the stick is round, octogonal, pentagonal or any other shape, and does it matter if it is made out of wood, carbon fiber, fiberglass, etc? If yes, what is the physical mechanism contributing to this (taking into account that if I put a vibrating tuning fork on the stick, it hardly produces any sound at all)?

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Yes, I think that the bow has an enormous effect on the sound.

The bow isn't just a stick that keeps the hair at the right tension to play the string. One could argue that a violin string of the right thickness, weight and tension should do it's job, and sound on a fiddle, but we all know that there's much more to strings than that, and that they can make or break a fiddle's sound. So too the bow.

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Yes, the bow is very decisive for the sound. Not only does it have to fit the violin and strings, but also the player. I recently tested a composite bow that was supposed to be good. I thought it was awful.

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Has anyone done a study of well matched violins and bows and poorly matched violins and bows to see if there is some measurable quality that explains why? i.e. frequencies that match up in a certain way?

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I have a dozen or so dfferent bows in the house, ranging in value from $100 to a few thousand dollars, and I can say that by picking up a different bow I get a different sound out of the same fiddle.  I have no scientific, acoustic explanation for that.  That's what happens.

 

I can say that some bows just feel better in the right hand than others, without even laying them on a string.  So maybe that's a factor.  Some bows are steadier in being drawn across a string, no quavering, and thus easier to draw across the string to get a steady tone.  No doubt that's a factor.

 

Materials for the stick do make a difference.  As a gross generalization I'd say carbon fiber gives a clearer, stronger, simpler tone, but perhaps less warm, less nuanced than pernambuco.  And different pernambuco bows give different tones.  I have one rather expensive bow in which the pernambuco is fairly porous and somewhat irregular.  That's a great bow for calming down a strident fiddle.

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I know that anecdotally, I will get a lot of positive responses - but I am looking for some actual evidence or physical explanation for why it is indeed so. For in the case of strings it is very easy to describe the effect. The whole apparatus that is the violin essentially distorts and amplifies the vibration of the strings, and thus produces the sound. If I have different strings of different materials they will vibrate differently, and being that the string vibration is Helmholtzian and thus non-linear, and the violin itself distorts and amplifies also in a non-linear fashion, it is easy to show, at least conceptually, that there is a great potential for difference even regarding minor differences in the strings.

 

With the bow I see no such connection. How does the bow stick interact with the sound? Obviously a player will obtain different sound from different bows - they balance differently, and will lead to the player choosing a different sounding point, applying different pressure, and drawing the bow at different speed. And he will probably set it at a different tension. All of this leads to different sound.

 

But if I had a robot draw the bow in exactly the same fashion, spot, pressure, etc, would the material of the stick make any difference? How does the bow stick interact physically with the sound apparatus of the violin?

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I think you must have misheard pooispoois, it's not the physical properties of a bow that make it sound better, it's the bow's fiscal properties that make all the difference. "Fiscal" means "relating to money, particularly to the earning and spending of money".  So the fiscal properties of a bow are determined by how much you sold it for, or bought it for.

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Nice one Bernie!

 

But to return to the OP's question ...

Does the player him/herself have an actual impact on sound?

It's a no-brainer, perhaps the most absurd question you could posit about playing the violin.

So, the bow is the way in which the player transmits musical intention to the violin. Obviously there's going to be a HUGE variation in how successful a particular bow is from the perspective of a particular player. To try to look at the bow in isolation from the particular player and the particular violin is pointless in the extreme. 

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I do not think it is "pointless in the extreme". If some bow makers are measuring "bow resonance" and using it to grade their bows how is it pointless to be able to understand whether there is any truth to that. I think in general, if you find the following statement controversial, then it is because the question is worth investigating:

 

"A bow stick's material itself is irrelevant as concerns production of sound, as long as it can regulate the tension of the bow hair attached. Any perceived improvement on sound brought out by a bow is purely a matter of better or worse technical articulation of the player in regards to the bow."

 

I did find Bernie's comment amusing!

 

Do not get me wrong though - I am not trying to force a specific conclusion. I am not a specialist on the matter and as such, I hold it plausible that the bow's stick material, shape, etc, could impact the sound. But I would like to get the facts straight on the issue.

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I didn't mean to be absolutist!

I don't find that statement controversial, just irrelevant in itself - HOW the bow regulates tension over time is the question.

Yes there are various measurable differences in performance of bows relating to density of the materials, weight distribution, sound transmission times, spring recovery, balance point, molecular structure of materials etc etc.

But these don't begin to tell you whether a particular bow will be a useful partner for a particular player and his or her violin.

You could draw up all sorts of scales and graphs by which to measure bows, but when it comes to the actual function as part of a holistic and interactive system, these measurements are probably unhelpful, just as weight in grams for instance is unhelpful.

It's a bit like the "problem" of tap tones. An impact hammer will give you all sorts of juicy data about how a violin reacts to being hit with an impact hammer, and very little information about how it reacts to being played by a particular individual.

I suppose what I was trying to say was that any measurement of a bow which doesn't relate to the passage of time within music would appear to be a bit pointless ...

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Personally, I think that many instrument "sound adjustment" techniques are effective, because they influence bow "slip-stick" properties more than basic resonating properties of the instrument.  That's partly based on an observation that an optimized adjustment can vary, based on which bow is used. No, I'm not prepared to take enough time away from income producing work to attempt to prove it to skeptics.

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My wife's bow will get better quality tone out of about any fiddle it is played on, whether it is her, me, or someone else playing it, compared to "lesser" bows that we have. I don't change how i play, or press, it is just the bow produces a better, fuller quality of sound . I don't ask why, but i know it to be fact. What i do, is keep my eye out for other bows that are close to as good.

I recently played a dozen fiddles with another good bow, and then with five or six other bows. The "good" one consistently got better sound out of every fiddle i played. File it under, "it is what it is".

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I wonder if you are getting that the right way round David. Wouldn't it be more accurate to say "changing the bow is likely to change the slip/stick properties, so the optimal adjustment will vary depending on the bow"? "Bow slip/stick properties influence adjustments", rather than "adjustments influence bow slip/stick properties".

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I wonder if you are getting that the right way round David. Wouldn't it be more accurate to say "changing the bow is likely to change the slip/stick properties, so the optimal adjustment will vary depending on the bow"? "Bow slip/stick properties influence adjustments", rather than "adjustments influence bow slip/stick properties".

I happen to think that the two are interchangeable, to some extent.

But I very much think that instrument adjustment influences hair/string interactions.

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If you hold a bow by the leather, and tap the head, you should feel a vibration that runs through the stick. I have a cello bow, a very good looking old German stick, that is absolutely dead. It simply seems to kill the string, and gives nothing to the cellist. It's an extreme example of a bad bow. It feels to me that a good bow is capable of resonating with the string, grabbing and releasing the string in just the right way.

I'm a very poor violin player, but I have a new bow by a good maker that seems to hug the string, and just makes the fiddle speak. It's an amazing sensation.

It's well worth listening to a couple of good players trying a selection of good bows. They are very likely to prefer different sticks, that work for them and their violins, and the differences in sounds can be vast.

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I'm a very poor violin player, but I have a new bow by a good maker that seems to hug the string, and just makes the fiddle speak. It's an amazing sensation.

 

That's also what a good instrument adjustment is to me. The bow "hugs" the string, as opposed to skating over the string. I believe one can actually feel more drag on the bow, once one is sensitized to it.

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I do agree with you Martin, that the question I have posed is ultimately not THAT relevant as concerns playing experience. A bow must be tried out, period; and it must be done by the player that is going to use it, in a setting as close as possible to the actual desired usage.

 

I also agree with David in that the slip/stick relationship makes a difference. In fact one just has to rosin the bow too much or to less to have a practical demonstration of this. I really had no doubts about this though - it's physically easy to explain (not so easy to model on those grounds on how sound adjustments might affect this - but it's completely plausible).

 

If you hold a bow by the leather, and tap the head, you should feel a vibration that runs through the stick. I have a cello bow, a very good looking old German stick, that is absolutely dead. It simply seems to kill the string, and gives nothing to the cellist. It's an extreme example of a bad bow. It feels to me that a good bow is capable of resonating with the string, grabbing and releasing the string in just the right way.

 

Now this is where I need the understanding. These phenomena are told all over the place - but is the stick itself to blame, rather than the amount/quality of hair/rosin or technique of the player (assuming a player can with enough training learn to adapt to an "oddly" balanced bow)?

 

Consider the following thought experiment: with the help of a materials engineer and a medium density plastic, I could without much effort write a program that took as an input a spatial density distribution and generated a ready to print (by a 3D printer) bow model that conformed to that density distribution (there are various techniques for varying density, one for example would be to generate a hive-like inner structure with strategically placed air pockets). All else being equal, would such a bow stick be any different than a pernambuco "master" bow with the same density distribution?

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A good bow will vibrate, numerous times, not just once, whether there is hair on it or not. A dead stick might take the initial tap as a vibration, and immediately stop, or barely respond at all.

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You can train yourself to feel the difference, and hear the difference. Some things are not rocket science, nor should they be. My wife can pick up a stick without hair, feel it, tap it, and tell me whether it is a decent bow or not. Once haired, she hasn't been wrong yet.

Music isn't science..it is feeling and hearing. Otherwise we would have robots playing everything for our listening "pleasure ".

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You can train yourself to feel the difference, and hear the difference. Some things are not rocket science, nor should they be. My wife can pick up a stick without hair, feel it, tap it, and tell me whether it is a decent bow or not. Once haired, she hasn't been wrong yet.

Music isn't science..it is feeling and hearing. Otherwise we would have robots playing everything for our listening "pleasure ".

 

True, but would you pay me for me to apply "magic snakeoil" on your bow in order to make it better? I would be sure to make it high priced and get plenty of peer pressure - it must work right?

 

Just because something isn't "just" science does not mean it can work by magic. There either is a basic mechanism for the bow stick to influence sound or there isn't; and if there isn't, there isn't. The most "masterish" bow and violin would still produce exactly 0 sound in space, no matter how much anyone wanted otherwise.

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Consider the following thought experiment: with the help of a materials engineer and a medium density plastic, I could without much effort write a program that took as an input a spatial density distribution and generated a ready to print (by a 3D printer) bow model that conformed to that density distribution (there are various techniques for varying density, one for example would be to generate a hive-like inner structure with strategically placed air pockets). All else being equal, would such a bow stick be any different than a pernambuco "master" bow with the same density distribution?

 

Do you need the 3D printer and the thought experiment? Get your robot to play pernambuco bows of similar dimensions and weight, with the same hair and rosin, on the same violin. My guess is, it will be very difficult to distinguish the bows by means of sound.

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If you hold a bow by the leather, and tap the head, you should feel a vibration that runs through the stick. I have a cello bow, a very good looking old German stick, that is absolutely dead. It simply seems to kill the string, and gives nothing to the cellist. It's an extreme example of a bad bow. It feels to me that a good bow is capable of resonating with the string, grabbing and releasing the string in just the right way.

I'm a very poor violin player, but I have a new bow by a good maker that seems to hug the string, and just makes the fiddle speak. It's an amazing sensation.

It's well worth listening to a couple of good players trying a selection of good bows. They are very likely to prefer different sticks, that work for them and their violins, and the differences in sounds can be vast.

According to some a good violin stick should cut out almost immediately when tapped ,whereas a viola bow should resonant longer, not sure about a cello bow.

Damping coefficient is one important property of bow stcks.

Heres some reading for you but probably wont answer your question.

 

0066.pdf

0068.pdf

0070.pdf

0072.pdf

Ablitzer_et_al_Violin_Bows_preprint.pdf

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As a professional player, i can tell you that your bow makes a tremendous difference, and the projection, articulation, and tone quality all vary greatly from bow to bow. Excellent bowmakers gain more control over various elements, but a bows personality needs to mesh well with a player and their instrument to function.

Bow sticks are not just there to hold tension on the hair, but vibrate sympathetically with the string, and as such have quite an effect on controlling the vibrations that are then amplified by the instrument (effectively an acoustic amplifier). You could even argue that its effects on sound are almost more important to a player than their instrument. 

Bows are made of different materials, and even discounting all talk of balance, the differences in those materials can make a tremendous difference in the sound of a bow. 

 

Pernambuco -  Obviously you have differences in sound velocity (lucchi reading), as well as density, strength, and straightness of grain. Every piece of wood absorbs and transmits sounds differently, depending upon the woods own molecular composition as well as its position in the tree, and in the individual board from which it is cut. The only way to begin to discern quality is by cutting the wood down, and tapping it, to begin to gauge the individual acoustic properties, and inspecting for its usability as a bow blank (straightness as well as density). This is only the tip of the iceberg. 

 

Ebony - Button and Frog are made of ebony. Depending upon its origin, its density and absorption can vary greatly, so the damping and amplifying effects it has on the bow are not to be underestimated. I imagine that a finished violin bow frog has at least 10 grams of ebony in it, so you're talking about a significant part of the vibrating mass of the bow here. Ebony/tortoiseshell/other materials make a difference too. 

 

Silver/Gold/Nickel - All Different mountings, different weights, different sonic characters, I'm sure. Smaller influence, probably, because much less is used in a bow than ebony or pernambuco. Still, some bows are made without an underslide in order to keep weight down, or to alter sonic properties. 

 

Winding - Wire/silk/tinsel/whalebone - These all alter the damping characteristics of the stick, especially because they wrap around it at the frog. Again, important!

 

This is just a brief overview of the variables here, all of which are important. Balancing them . . . . well, that's why it's just as much art as science. 

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