Sign in to follow this  
jezzupe

energy storage and release

Recommended Posts

19 minutes ago, violinsRus said:

Not to derail the thread, but can you tell me briefly why vibrations in a gong is non-linear and in a violin it's linear? 

Linearity briefly means that restoring force is proportional to deflection, in all mode shapes.  Using a string as an example, it will be linear if the tension is constant.  For a steel-core G string, large deflections cause the core to increase in tension, thus the string frequency rises when there are large deflections... so it can go slightly non-linear.

I'm not a gong engineer, but somehow the huge gong in the video was made specifically to have non-linearities that cause energy to bleed out of the low-frequency mode into the higher modes.

I don't think that wolf notes, adjustments, or bowing variables are any indication of non-linearities in the violin structure, although there could be some non-linearities in the bow/string interaction.

Share this post


Link to post
Share on other sites

I'm not sure what the pitch of the Gong is, but it interesting how it seems to have many frequency ranges all going at the same time and that if one were using it as a drone and singing with it how it seem like it would be hard to pick out the right notes to sing over it, as if it were "keyless" . I hear many pitches, I'm just not sure what the main one is.

Share this post


Link to post
Share on other sites
2 hours ago, jezzupe said:

I'm not sure what the pitch of the Gong is, but it interesting how it seems to have many frequency ranges all going at the same time and that if one were using it as a drone and singing with it how it seem like it would be hard to pick out the right notes to sing over it, as if it were "keyless" . I hear many pitches, I'm just not sure what the main one is.

Lot's of objects vibrate with less specific pitch (unless driven).  That specificness of pitch depends on geometry, and many other factors. 

A round shape like that can have specfic pitch, but they added complications to the shape that make it less so.

Share this post


Link to post
Share on other sites
5 hours ago, jezzupe said:

I'm not sure what the pitch of the Gong is, but it interesting how it seems to have many frequency ranges all going at the same time and that if one were using it as a drone and singing with it how it seem like it would be hard to pick out the right notes to sing over it, as if it were "keyless" . I hear many pitches, I'm just not sure what the main one is.

You are probably correct that there is a directional dominant pitch ( audible somewhere near the edge of the gong? ) A pitch ( or a series of pitches ) would be more defined if more energy was input at impact, i would assume...

Bass drums can be pulled tighter up to pitch or loosened to create a less defined "Whapp." The Dies Irae movement from the Verdi Requiem often has a defined pitch. I did play a performance where the conductor wanted no identifiable pitch and it was scary as it rang the hall with this explosion. It was jarring. Even though it would be awesome to have twelve huge diatonic ( western scale-wise ) gongs in the symphony warehouse, a set at a = 440hz, a = 442hz and a = 443hz, that might be too much at about $30k USD each. My guess is that they cast quite a few gongs and stamp ( possibly hammer ) contours into them to increase its structural strength and are reliably balanced for maximum sustain. Then an artist is assigned to hammer random peaks and valleys through out the edges of the instrument to encourage the dissipation of standing waves across the circle. 

I guess it's better not to have a defined pitch.

That is the biggest gong i have seen, except possibly in cartoons and comedic movies.

Share this post


Link to post
Share on other sites

Something nobody has really gotten into yet is how these gongs are made, and what their structure is like.  http://www.paistegongs.com/manufacture.php    Obviously, the combination of workhardening, annealing, and thickness graduation, applied differently to local areas of the bronze, is producing a complicated variety of dislocated crystalline structures as well as a variety of local oscillating domains.  I'd guess that, like the violin, these symphonic gongs might defy dynamic analysis.  :huh::)

Share this post


Link to post
Share on other sites
1 hour ago, GoPractice said:

You are probably correct that there is a directional dominant pitch ( audible somewhere near the edge of the gong? ) A pitch ( or a series of pitches ) would be more defined if more energy was input at impact, i would assume...

Bass drums can be pulled tighter up to pitch or loosened to create a less defined "Whapp." The Dies Irae movement from the Verdi Requiem often has a defined pitch. I did play a performance where the conductor wanted no identifiable pitch and it was scary as it rang the hall with this explosion. It was jarring. Even though it would be awesome to have twelve huge diatonic ( western scale-wise ) gongs in the symphony warehouse, a set at a = 440hz, a = 442hz and a = 443hz, that might be too much at about $30k USD each. My guess is that they cast quite a few gongs and stamp ( possibly hammer ) contours into them to increase its structural strength and are reliably balanced for maximum sustain. Then an artist is assigned to hammer random peaks and valleys through out the edges of the instrument to encourage the dissipation of standing waves across the circle. 

I guess it's better not to have a defined pitch.

That is the biggest gong i have seen, except possibly in cartoons and comedic movies.

More to do with Q of design/shape.  Less about impact energy.

With those curled sides, what is the width across the gong?  The less defined such answers, the lower the Q, the less specfic the pitch, the less narrow the response.

Share this post


Link to post
Share on other sites

well design as well as how it is hanging  definitely has lots to do with it....or it's not the size of the gong that matters :lol:

this gong, much larger, sounds pretty crappy

 

Share this post


Link to post
Share on other sites
2 hours ago, GoPractice said:

You are probably correct that there is a directional dominant pitch ( audible somewhere near the edge of the gong? ) A pitch ( or a series of pitches ) would be more defined if more energy was input at impact, i would assume...

Bass drums can be pulled tighter up to pitch or loosened to create a less defined "Whapp." The Dies Irae movement from the Verdi Requiem often has a defined pitch. I did play a performance where the conductor wanted no identifiable pitch and it was scary as it rang the hall with this explosion. It was jarring. Even though it would be awesome to have twelve huge diatonic ( western scale-wise ) gongs in the symphony warehouse, a set at a = 440hz, a = 442hz and a = 443hz, that might be too much at about $30k USD each. My guess is that they cast quite a few gongs and stamp ( possibly hammer ) contours into them to increase its structural strength and are reliably balanced for maximum sustain. Then an artist is assigned to hammer random peaks and valleys through out the edges of the instrument to encourage the dissipation of standing waves across the circle. 

I guess it's better not to have a defined pitch.

That is the biggest gong i have seen, except possibly in cartoons and comedic movies.

When I hum an E over it , it seems to go pretty well, strangely as the volume increases, the pitch changes, but seems to hover around E'ish to me at least

Share this post


Link to post
Share on other sites
On ‎8‎/‎12‎/‎2019 at 10:13 AM, Violadamore said:

No, the simple statement, y(x,t) = A sin(kx - ωt) + A sin(kx + ωt) = 2A sin(kx)cos(ωt), as well as the somewhat more complicated expressions describing a driven damped harmonic oscillator, remain true in both cases,

The violin and the gong are vibrating systems and so share similarities. But your simple traveling wave solution would fail to predict the motion of many classes of damped harmonic oscillators.

 

 

Share this post


Link to post
Share on other sites
2 minutes ago, ctanzio said:

The violin and the gong are vibrating systems and so share similarities. But your simple traveling wave solution would fail to predict the motion of many classes of damped harmonic oscillators.

 

 

Yup, please note the words between "as well as", and "remain true".  I was trying to not overcomplicate my post.  :)

Share this post


Link to post
Share on other sites
On 8/14/2019 at 1:04 AM, jezzupe said:

I'm not sure what the pitch of the Gong is, but it interesting how it seems to have many frequency ranges all going at the same time and that if one were using it as a drone and singing with it how it seem like it would be hard to pick out the right notes to sing over it, as if it were "keyless" . I hear many pitches, I'm just not sure what the main one is.

A Gong functions in a way similar to that of a drum which is a circular membrane I dug out a physics mathematics text and found out some facts about the vibration of a circular membrane.  It says a circular membrane has 2-fold-complex vibration modes and has something to do with Bessel functions.  <_<

The modes are determined by the zeros of Bessel functions.  (where for a vibration string, the resonance frequencies are determined  by zeros of sine or cosine functions.)

This has an important consequence that the higher mode frequencies are no longer integer multiples of the fundamental mode frequency.  ( Actually, I believe it would be even more complicated for a violin.) 

In my opinion, the key difference is that the resonance box of a violin is driven by the strings where a Gong is driven by a mallet. When the string is plucked, it carries a fundamental frequency and its integer multiples to the resonance box.  In contrast to a string, when a mallet hits a Gong, it carries a spike of shuck wave to the Gone. And a spike actually consists of ALL frequencies.  That's why a Gone gives out all kinds of frequencis at a time where as  a violin radiates a fundamental sound and its harmonics only.  

 

violin:   plucking (all freq.) --> a string of fixed length ( fundamental and harmonics only) --> resonance box(all freq.) ==> pure hormonic sound

Gong:   a hammer strike(all frequencies) --> Gong (all freq.)  ==>  sound of  all kind of frequencies

 

S__1368066.thumb.jpg.1978e145a748019c1ccf7a2702655a92.jpg

Edited by Kae
typo, additional content

Share this post


Link to post
Share on other sites
On 8/13/2019 at 6:04 PM, jezzupe said:

well design as well as how it is hanging  definitely has lots to do with it....or it's not the size of the gong that matters :lol:

this gong, much larger, sounds pretty crappy

It's impossible to judge how that giant gong "sounds" when it is just whacked at the edge by a tourist, as opposed to struck in the right place, and the right amount, by a gong master... as in the first video.  He'd probably need a gigantic stepladder, though.

A non-playing tourist would probably make the Cannone sound pretty crappy too, although there's no way the guards would let that happen.

Share this post


Link to post
Share on other sites
22 hours ago, Kae said:

A Gong functions in a way similar to that of a drum which is a circular membrane I dug out a physics mathematics text and found out some facts about the vibration of a circular membrane.  It says a circular membrane has 2-fold-complex vibration modes and has something to do with Bessel functions.  <_<

The modes are determined by the zeros of Bessel functions.  (where for a vibration string, the resonance frequencies are determined  by zeros of sine or cosine functions.)

This has an important consequence that the higher mode frequencies are no longer integer multiples of the fundamental mode frequency.  ( Actually, I believe it would be even more complicated for a violin.) 

In my opinion, the key difference is that the resonance box of a violin is driven by the strings where a Gong is driven by a mallet. When the string is plucked, it carries a fundamental frequency and its integer multiples to the resonance box.  In contrast to a string, when a mallet hits a Gong, it carries a spike of shuck wave to the Gone. And a spike actually consists of ALL frequencies.  That's why a Gone gives out all kinds of frequencis at a time where as  a violin radiates a fundamental sound and its harmonics only.  

 

violin:   plucking (all freq.) --> a string of fixed length ( fundamental and harmonics only) --> resonance box(all freq.) ==> pure hormonic sound

Gong:   a hammer strike(all frequencies) --> Gong (all freq.)  ==>  sound of  all kind of frequencies

 

S__1368066.thumb.jpg.1978e145a748019c1ccf7a2702655a92.jpg

yes, I suppose it's the same as when tapping a free plate, everything is excited at the same time

Share this post


Link to post
Share on other sites
On 8/13/2019 at 8:20 PM, jezzupe said:

When I hum an E over it , it seems to go pretty well, strangely as the volume increases, the pitch changes, but seems to hover around E'ish to me at least

 

22 hours ago, Kae said:

A Gong functions in a way similar to that of a drum which is a circular membrane I dug out a physics mathematics text and found out some facts about the vibration of a circular membrane.  It says a circular membrane has 2-fold-complex vibration modes and has something to do with Bessel functions.  <_<

( .... )

( ... ) 

In my opinion, the key difference is that the resonance box of a violin is driven by the strings where a Gong is driven by a mallet. When the string is plucked, it carries a fundamental frequency and its integer multiples to the resonance box.  In contrast to a string, when a mallet hits a Gong, it carries a spike of shuck wave to the Gone. And a spike actually consists of ALL frequencies.  That's why a Gone gives out all kinds of frequencies at a time where as  a violin radiates a fundamental sound and its harmonics only.  

Finally found a laptop with some speakers in it, though a good set of headphones is likely the better experience. 

On the multiple strikes after then initial energizing of the gong, there are ebs ( e flats ) that rise possibly to a g? When he bows the gong the tone starts at around a bb ( b flat ) and rises. 

I think Kae offers good information, but it's the starting point. I have heard of Bessel functions but applied to drum, bass drum, and timpani head where there are relatively uniform thicknesses. Also as part of a computer modeling of a cello made of two circles and a bass bar. But the hammering of the metal of a gong ( bronze-ish alloy? ) results in slight but various thicknesses and densities. Is there enough variation in the material to not consider it a membrane? This is all relative to the levels of excitation of the membrane.

My observations were related to the lack of energy input into the gong. For those of us who are mostly accompanists in the orchestra - 2nd violin, viola, cello, pit player - the defining of pitch ( its clarity ) from an instrument at low volumes is a major consideration. This is an oversimplification but better pitch quality allows many of us to play both quieter and louder when necessary. The danger is that it can sound thin and insubstantial. If a singer, or solo recorder ( baroque flute, also ) or solo Bass needs to be heard, the orchestra can reduce the number of players on stage. Or the soloist management can request all  string players on stage ( to make the soloist appear more impressive ) to not rosin their bows ( just kidding, but possible ) or both.

The opposite can be said for a gong where a non- defined pitch at low volumes can sound like a roar. It's very effective when necessary. But if it is the last sound of a piece, some audiences start applauding before the sound completely decays out. 

Share this post


Link to post
Share on other sites
7 hours ago, Don Noon said:

It's impossible to judge how that giant gong "sounds" when it is just whacked at the edge by a tourist, as opposed to struck in the right place, and the right amount, by a gong master... as in the first video.  He'd probably need a gigantic stepladder, though.

A non-playing tourist would probably make the Cannone sound pretty crappy too, although there's no way the guards would let that happen.

Well it would be cool to hear it's true voice, and I suppose it's interesting to think that there are "gong masters" whereas I think most think of playing the gong as, well, just walking up to it and whacking it.

Well becoming a gong master seems like a nice retirement goal, one of those seemingly simple things that one could spend a lifetime pursuing, like becoming a tea master

and ya, about the Cannone, just imagine some real confused guy coming at it with a mallet thinking it was a gong :lol:

Edit; also, glad you said "in the right place"  in thinking about this more, seemingly obvious, that by "tapping" the outer edge {nodal} it would be the same as trying to tap a violin plate on the outer edge, wrong place to get any ringing, duh....that's why you're the rocket scientist Don.:lol:

 

Share this post


Link to post
Share on other sites
1 minute ago, GoPractice said:

 

Finally found a laptop with some speakers in it, though a good set of headphones is likely the better experience. 

On the multiple strikes after then initial energizing of the gong, there are ebs ( e flats ) that rise possibly to a g? When he bows the gong the tone starts at around a bb ( b flat ) and rises. 

I think Kae offers good information, but it's the starting point. I have heard of Bessel functions but applied to drum, bass drum, and timpani head where there are relatively uniform thicknesses. Also as part of a computer modeling of a cello made of two circles and a bass bar. But the hammering of the metal of a gong ( bronze-ish alloy? ) results in slight but various thicknesses and densities. Is there enough variation in the material to not consider it a membrane? This is all relative to the levels of excitation of the membrane.

My observations were related to the lack of energy input into the gong. For those of us who are mostly accompanists in the orchestra - 2nd violin, viola, cello, pit player - the defining of pitch ( its clarity ) from an instrument at low volumes is a major consideration. This is an oversimplification but better pitch quality allows many of us to play both quieter and louder when necessary. The danger is that it can sound thin and insubstantial. If a singer, or solo recorder ( baroque flute, also ) or solo Bass needs to be heard, the orchestra can reduce the number of players on stage. Or the soloist management can request all  string players on stage ( to make the soloist appear more impressive ) to not rosin their bows ( just kidding, but possible ) or both.

The opposite can be said for a gong where a non- defined pitch at low volumes can sound like a roar. It's very effective when necessary. But if it is the last sound of a piece, some audiences start applauding before the sound completely decays out. 

The 80" gong master in an orchestra is probably the first guy to arrive and the last guy to be heard

Share this post


Link to post
Share on other sites

I wonder if you can compare a gong to a violin. 

A violin as a matter of fact needs permanent energy input and has to produce different frequencies. If it vibrates on its own we have something like a wolf note which can't be controlled by the player. (I guess no violinist wants to have that)

I look on it rather than two vibrating systems coupled together. Strings are an active system which operates as the driver and the entire body is a sort of passive vibrating system which amplifies the sound and acts simultaneously as a sound spectrum filter. 

Share this post


Link to post
Share on other sites
45 minutes ago, Andreas Preuss said:

I wonder if you can compare a gong to a violin. 

A violin as a matter of fact needs permanent energy input and has to produce different frequencies. If it vibrates on its own we have something like a wolf note which can't be controlled by the player. (I guess no violinist wants to have that)

I look on it rather than two vibrating systems coupled together. Strings are an active system which operates as the driver and the entire body is a sort of passive vibrating system which amplifies the sound and acts simultaneously as a sound spectrum filter. 

Gongs and violins?  A sufficiently obsessed and demented scientist (or any ordinary politician) can compare apples and oranges.......  :lol:

IMHO, the bow is the combined driver and modulator, the strings are the oscillator, and the rest of the system acts as a combined filter and impedance transformer to couple the vibrations in the violin body to the air around it.  That said, the violin's apparent simplicity conceals mysteries that I feel humble in the presence of.  The things are fascinating, and excite my sense of wonder.  :)

Share this post


Link to post
Share on other sites

Violins aren't simple. 

For one, they have sort of 'subsystems' that behave in distinct ways, but are all intimately connected and influence each other. So, for example, the stick slip action puts a random (unpitched) vibrational stimulus into the strings.  But the strings are very high Q and put a good portion of that bow energy into the pitches of the strings resonances.  But the strings in turn drive the violin body via the bridge feet. Unlike the bow energy into the strings, the energy from the strings into the boby is now a 'pitched signal' that drives the response of the body.  The body is much lower Q and responds with standing waves whose frequency have bent to follow the drive from the strings.  The air inside is a further subsystem that is only directly stimulated by coupling with the body.  The body and air together are following the  drive from the strings.  Lastly, the larger motions of the body and air inside radiate their energy into the surrounding air. 

Primarly there are three different sorts of stimulation that behave differently:

1) a pulse input.  So a hit or pluck.  The energy comes into a mass in a sudden simple event.  Initially, such energy lacks oscilation or pitch. It will express itself in an object is complex and depends many factors.  This energy may or may not lead to pitches.

2) a recurring but random vibration stimulation.  Bows and other stick slips are examples. There are others, like aire flutter.  

These are very good at stimulating even somewhat unstable resonance.  But  like with impulse, the originating energy is unpitched.  The results will depend on many factors and the on the object being stimulated. 

3) Driven signals:

This is what comes from the strings into the body and air of the instrument.  The responce still depends on many factors, but the responce is primarily about following the drive.

 

Those are the most basic differences between input energies.

And the most basic differences in object responses?

Elastic versus Inelastic:

Not to be confused stiffness.  Peanut butter is inelastic becasue it wastes input energy by simply deforming.  Elastic materials store energy  by flexing/compressing and then returning the energy in some sort of bounce back.

Air, metal, gut, wood all tend to elastical return energy put in.

 

High Q versus low Q:   strings are high Q, soundboard are low Q.  High Q easily takes random energy and returns pitched energy.       Low Q readily sets up standing waves that follow a driving input aignal.

 

Complex objects/systems versus simple:    a string is very simple in the scheme of things; a violin not so.

Objects will respond to energy in all possible ways at once.  But the energy will first and fastest go where easiest.  'Easiest' can depend on many factors.

 

Time and buildup are factors in an object's response to energy.

 

 

Share this post


Link to post
Share on other sites
1 hour ago, Andreas Preuss said:

I wonder if you can compare a gong to a violin. 

A violin as a matter of fact needs permanent energy input and has to produce different frequencies. If it vibrates on its own we have something like a wolf note which can't be controlled by the player. (I guess no violinist wants to have that)

I look on it rather than two vibrating systems coupled together. Strings are an active system which operates as the driver and the entire body is a sort of passive vibrating system which amplifies the sound and acts simultaneously as a sound spectrum filter. 

I think of the gong as what would be a component of a violin, a free plate, but one that acts dramatically differently based on its material properties, size, shape and thickness.

the few aluminium violins i have heard were awful, but I wonder about a larger instrument, like a cello or bass...

I think it would be interesting to have a violin that has as much release and reduced decay as a gong, almost like a piano with the sustain pedal pressed down , but instead of it being the string that ring forever it would be the body, I know in this day and age we can get electric violins to sound as I'm describing, I just think it would be neat to somehow introduce gong like sustain into the build somehow, even tough I don't think it's possible to build a violin sized instrument that body rolls like a bowl of jello forever.

Share this post


Link to post
Share on other sites
Just now, David Beard said:

The back plate already is a sort of wooden gong.

right, it's just a big free plate, but a lot different

Share this post


Link to post
Share on other sites
4 hours ago, jezzupe said:

...

I think it would be interesting to have a violin that has as much release and reduced decay as a gong, almost like a piano with the sustain pedal pressed down , but instead of it being the string that ring forever it would be the body, I know in this day and age we can get electric violins to sound as I'm describing, I just think it would be neat to somehow introduce gong like sustain into the build somehow, even tough I don't think it's possible to build a violin sized instrument that body rolls like a bowl of jello forever.

I have such a violin, or rather a fiddle. I have no idea why, but is sounds like a Hardanger fiddle even if it has only the normal four strings.

I believe the back is of black alder, apart from that I know nothing.

Share this post


Link to post
Share on other sites
12 hours ago, jezzupe said:

right, it's just a big free plate, but a lot different

Yes.  And like a back plate, and extra load of mass near the center is essential to a gong.

The sort of 'build up' we hear in a gong is the energy of the strike vibrating many smaller bits of the gong during the time before getting the central mass and lowest and slowest reaponses of the gong going.

I find gongs fascinating because the time aspects of response are so evidently displayed.

Also, the common orchestral technique of shimmering the gong with quite stimulation to prepare a main strike is very intriguing.  If you want a great splashing gong sound, you can't just wack it.  You have to ready the gong before giving a huge blow.

 

I beleive we can improve our intuitions for musical behavior by contemplating such things.

You can consider tables for example.  Some strikes of a table make unpitched sound.  Some strikes make pitched sounds with one table but not another.  Some strikes send a table across the room.  Some strikes destroy the table.  Most strikes give complicated combinations of response from different parts of the table.  And often the responses change through time.

How well can you understand what happens to the energy in these different cases. How well can you predict such things?

Also, sometimes a table can act as an excellent soundboard to radiate driven signals, like tuning forks held against them.  How well can you understand why one table does this well but another doesn't?

All of these contemplations are much simpler than trying to understand a violin.

 

Share this post


Link to post
Share on other sites
18 hours ago, jezzupe said:

I think of the gong as what would be a component of a violin, a free plate, but one that acts dramatically differently based on its material properties, size, shape and thickness.

the few aluminium violins i have heard were awful, but I wonder about a larger instrument, like a cello or bass...

I think it would be interesting to have a violin that has as much release and reduced decay as a gong, almost like a piano with the sustain pedal pressed down , but instead of it being the string that ring forever it would be the body, I know in this day and age we can get electric violins to sound as I'm describing, I just think it would be neat to somehow introduce gong like sustain into the build somehow, even tough I don't think it's possible to build a violin sized instrument that body rolls like a bowl of jello forever.

Wow! It's the first time I heard of aluminum violins.  I just found some video on YouTube, and there is a video for  aluminum violin&cello Duet.  To my surprise, they are  not so weird as I thought they would be,.       Well, .....hmm...... they are still a bit weird.   :D

 

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.