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Author Topic: Reed Block Acoustics  (Read 24865 times)

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Owen Woods

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Re: Reed Block Acoustics
« Reply #20 on: February 18, 2012, 04:06:17 PM »

I do not strongly doubt the argument that it doesn't too much matter the material of the block, and my recent balsa block project helps confirm that, but if so, why does it make such a drastic difference if the reed is on an aluminum or brass base?  Why shouldn't the material that the plate is attached to also make a difference?  I also think there is a distinction between what make no difference and what can make a little difference. A little difference can be the difference between preferring this accordion or that one.

So I'm guessing that it's to do with the stiffness of the plate. If the plate vibrates then it is going to (probably adversely) affect the sound. And the plate is a large area which is attached by wax, which is pliable. So the plate is the most likely part of the block to vibrate. I hear what you are saying and agree that probably the material of the block does make a little bit of difference, but that the construction of the block makes far more of an affect.

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With my last 2 projects, I also helped confirm Digitonix's report that a bigger sound hole is better, which also kills what I had previously thought.  I assumed that a hole needed to be big enough, but too big would use too much air.  So I made square holes, which added quite a bit more surface area than my round holes.  I can tell no difference in air consumption, but a noticeable difference in volume and richness of sound. Still can't help but think there is a point of diminishing returns.

There is a point of diminishing returns, but I think that would come when the hole comprises the majority of the chamber, i.e. at the point at which you stop having a chamber and instead have a semi-enclosed space. One of the papers that I linked to showed that having a chamber gave better response at the 1-3kHz range, which is what we perceive as "definition" (I'm told). So if you stop having a chamber at all then the sound will change a fair bit. But for a conventional melodeon that would never happen.

Quote
Back to blocks. Also as an experiment, I made my blocks on another accordion (with my conventional maple blocks) with dual level chambers.  The thought was since the push/pull reeds are set the space of the plate apart, I would try to take up that space under the push reed. First impression was inconsistent.  Some reeds seemed louder, and some choked.  So I tried shaving down the top of the raised portion under the tip of the push reed, problem solved.  My next 3 will also have these stepped chambers, so hopefully I'll be able to see if it is consistently better than what I had been doing.

Do you mean that you shaped the inside of the chamber such that there was less wood under the push reed? This is done in high end PAs I think, Thierry Benetoux shows some pictures of such blocks in "Sounding out the Accordion". It makes sense to do that, as it should mean that the flow to the reeds is more consistent across push and pull. I think.

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My experiments have very little scientific thought, but a whole lot of "what if..",but is definitely the fun part for me.

Don't knock yourself, this is how innovation happens, by people trying things out!

You may be on to something with the mention of starting transients. It's well known that much of the recognisable character of the sound of a musical instrument is in the way the notes start. Snip those off recordings of a flute and a trumpet playing the same note, for example, and they sound surprisingly similar. The speed of starting also affects the feel of the instrument for the player, and is a major difference between good reeds and bad reeds.


Quite. The question is to what degree the flat mounted reeds give a different sound. For instance, there is a difference between quicker response and a different mechanism. Both may be transient (probably would be), but the interesting thing is knowing whether the difference in sound is due to a different mechanism or the same mechanism being excited in a slightly different way. The first is a definite argument for flat mounted reeds, the other encourages experimenting with making block mounted reeds respond better, as diatonix and Bryan have done.

So it'll be interesting to see what flat-mounted reeds (short air path) Allen-bolted down to a milled aluminium "reed pan" with no gaskets sound like, the reed should think it's mounted directly on a big rigid metal block and you can't much get more massive and rigid than that...  ;)

Ian

I literally cannot wait to find out. Got a due date yet?

Anahata, this observation (and ukebert's) is crucial -- thank you! It might deserve another topic.  But in my opinion, this factor also is highly influential in the differences among playing styles developed by good musicians who play dance music.  Some musicians seem to have developed a style using very high bellows pressure to get quick response and good articulation of rhythms at a micro time scale, and this can work with reeds that are less than optimally efficient and/or somewhat leaky instruments. You can achieve the accuracy without harshly overblowing the reeds on the attack.  Other musicians have a lower-pressure style that depends on extremely efficient reeds and very tight instruments to achieve those great dance rhythms.  Each approach can sound accurate and tonally beautiful, on the appropriate instruments for each style.

This is quite true and is one of the problems with studying musical instruments - you can create the best musical instrument in the world for one particular thing and people can turn around and say "But I want it to do x". There is no right answer and there is no definitive best sound. Which from a scientist's point of view is a bit of a pain but from a musician or builder's view is one of the most exciting things about working with instruments.

I have played a highly customized Hohner Amatona (a 4 voice D/D#) years ago, owned by a very creative and handy guy.  The reedblocks had been modified to have metal bases (aluminum or stainless, I can't remember which), machined to exactly mate surface-to-surface on a metal soundboard, and locked in place to yield an airtight metal-to-metal fit with no gasket.  This box had a really unique, rich, bright and present sound, but it had many other modifications also (for example the original grille was off and an open, curved metal "collar shape" installed) and I don't know what it sounded like before the reedblocks were modified.

I'm struggling to visualise a collar shaped grille, but that idea for the reedblocks is interesting, it seems that gaskets do have quite an impact on how the box sounds, which isn't altogether surprising. So Ian's box will be very interesting in that regard.
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blafleur

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Re: Reed Block Acoustics
« Reply #21 on: February 18, 2012, 04:19:39 PM »

  but that the construction of the block makes far more of an affect.

Quote

But I don't think we should concentrate on just the things that have the biggest affect, the little nuances can make the difference in a good sounding accordion, or an exceptional one, and vice versa.
 

 

Do you mean that you shaped the inside of the chamber such that there was less wood under the push reed? 

Quote


There is more wood under the push reed.  The push reed is the thickness of the reed plate higher than the pull reed, so I added a strip of wood to take that amount of space up.

Also big area pallet holes in a thin pallet board are better (my Oakwood used big rectangular holes), as is a clear open path for air flow to the reed. Bigger holes don't use more air, by far the smallest cross-section in the air flow path is the reed in its frame.


Ian

Additionally, my assumptions, also maybe wrong, were that there should be some degree of pressure build up in the chamber, not for volume but tone.

blafleur

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Re: Reed Block Acoustics
« Reply #22 on: February 18, 2012, 04:21:16 PM »

And I obviously know even less about using the multiple quote feature

Owen Woods

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Re: Reed Block Acoustics
« Reply #23 on: February 18, 2012, 04:31:53 PM »

But I don't think we should concentrate on just the things that have the biggest affect, the little nuances can make the difference in a good sounding accordion, or an exceptional one, and vice versa.
 

This is perfectly true. What I meant was that it is conceivable that the material of a reedblock might make a noticeable affect on the sound and it is conceivable that it doesn't. The difference between them may be that one has a different construction than the other. i.e. that the construction can make the affect of the material so tiny that you wouldn't notice it. But of course, the only way to know is to test it, which you have done (:)

Quote
There is more wood under the push reed.  The push reed is the thickness of the reed plate higher than the pull reed, so I added a strip of wood to take that amount of space up.

Sorry, typed the wrong thing. Yes, that's what is described in Sounding Out. You found that it improved the response of the push reed?

Quote
Additionally, my assumptions, also maybe wrong, were that there should be some degree of pressure build up in the chamber, not for volume but tone.

You may be right, but I think that Ian's point was that the resistance of the reed is so huge compared to the hole that increasing or decreasing the resistance of the opening by changing the hole diameter isn't going to change the pressure in the chamber hugely. Correct me if I'm wrong Ian. With a larger hole, however, the air flow will be cleaner and more direct into the chamber, which is important for the sound.

I think I'm using affect and effect wrong. This is what 4 years of studying a numerate subject does to you :P
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Re: Reed Block Acoustics
« Reply #24 on: February 18, 2012, 04:37:32 PM »

This thread is most interesting to me as I have started an Open University Technology of Music Course and this discussion seems in point.  I shall bookmark it and return to it when (if) I learn something from the course.
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Re: Reed Block Acoustics
« Reply #25 on: February 18, 2012, 05:22:01 PM »

This thread is most interesting to me as I have started an Open University Technology of Music Course and this discussion seems in point.  I shall bookmark it and return to it when (if) I learn something from the course.

Oh good - you're going to come back and tell us all the answers  ;)
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IanD

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Re: Reed Block Acoustics
« Reply #26 on: February 18, 2012, 05:25:51 PM »

But I don't think we should concentrate on just the things that have the biggest affect, the little nuances can make the difference in a good sounding accordion, or an exceptional one, and vice versa.
 

This is perfectly true. What I meant was that it is conceivable that the material of a reedblock might make a noticeable affect on the sound and it is conceivable that it doesn't. The difference between them may be that one has a different construction than the other. i.e. that the construction can make the affect of the material so tiny that you wouldn't notice it. But of course, the only way to know is to test it, which you have done (:)

Quote
There is more wood under the push reed.  The push reed is the thickness of the reed plate higher than the pull reed, so I added a strip of wood to take that amount of space up.

Sorry, typed the wrong thing. Yes, that's what is described in Sounding Out. You found that it improved the response of the push reed?

Quote
Additionally, my assumptions, also maybe wrong, were that there should be some degree of pressure build up in the chamber, not for volume but tone.

You may be right, but I think that Ian's point was that the resistance of the reed is so huge compared to the hole that increasing or decreasing the resistance of the opening by changing the hole diameter isn't going to change the pressure in the chamber hugely. Correct me if I'm wrong Ian. With a larger hole, however, the air flow will be cleaner and more direct into the chamber, which is important for the sound.

I think I'm using affect and effect wrong. This is what 4 years of studying a numerate subject does to you :P

Exactly what I meant -- almost all the pressure drop will be across the reed, what seems to matter most for sound is clean air flow -- especially to the tip of the reed where most of the air flows -- and least obstruction in the air path.

This is why with normal reed blocks the lower reeds are mounted "tips up", so the air flow from the pallet hole goes up the cavity and out past the reed tip; if they're "tips down" the air flow has to kind of reverse direction. The highest reeds work better "tips down" because this allows a smaller reed cavity and there is much less air flow anyway.

With flat-mounted reeds placed with the tip end directly over the pallet hole the path is more direct still and with less resistance to air-flow because it doesn't have to flow along a cavity, it can just go straight past the reed tip without even turning 90 degrees.

The only time when big chambers are really needed is with low bass reeds which start slowly, and being big tongue area and relatively flexible are prone to choking if the pressure in the chamber builds up before they've started. A big chamber will slow down the rate of pressure change when the pallet opens, and also allows air to flow around the reed more easily if there's a big clearance to the walls of the chamber. This is probably why Helikon basses often have the lowest and octave reeds on one plate; the upper one starts faster and helps to relieve the pressure in the (big) chamber. However this then means less air for the higher reed (quieter) once the low one does start, so might not always be such a good thing unless you want the "parp-y" tuba sound...

I've measured the size of the chamber in the reed blocks on my 3 D/G boxes, and there seems to be good correlation between the quality of the bass reed sound (and resistance to choking) and the size of the chambers (biggest is best). It seem that often these aren't big enough in melodeons, especially small ones -- the reed blocks need to be deeper, wider or both.
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Re: Reed Block Acoustics
« Reply #27 on: February 18, 2012, 05:30:07 PM »

This thread is most interesting to me as I have started an Open University Technology of Music Course and this discussion seems in point.  I shall bookmark it and return to it when (if) I learn something from the course.

Oh good - you're going to come back and tell us all the answers  ;)

I think the problem is that *nobody* knows all the answers for free-reed instruments, there's been far too little serious investigative work (as opposed to anecdotes or opinions) done on them to see what really affects the sound -- or at least, that has been published so people know about it...
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Andrew Wigglesworth

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Re: Reed Block Acoustics
« Reply #28 on: February 18, 2012, 05:53:54 PM »

... and to throw another spanner in the works, we're dealing with human perceptions.

We all blithley go along thinking that we "hear sound" when in fact this is a creation of the human brain interpreting reactions from parts of the body. The interpretation is also acclimitised to particular experiences and the environment. People brought up using different languages will even hear human speech differently with one group completely unable to differentiate certain sounds that are plainly separate for another group.

This is not to say that things are unknowable, and I'm not throwing in a bit of "woo" to say that science is meaningless, far from it. But if anyone thinks that you can simply wave a sound pressure meter and an osciloscope at a melodeon and come up with a definitve answer then I think they are misguided.

Psycho-acoustics I think it's called.

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Re: Reed Block Acoustics
« Reply #29 on: February 18, 2012, 06:01:16 PM »



I think the problem is that *nobody* knows all the answers for free-reed instruments, there's been far too little serious investigative work (as opposed to anecdotes or opinions) done on them to see what really affects the sound -- or at least, that has been published so people know about it...

That's true, we all just guess based on our ideas and our own experiences, and it's so hard to experiment because of the huge amount of time it takes to build the components.  What has always amazed me is how efficient and well thought out turn of the century accordions were considering how new the concept was.  Taking into account technology and improved materials, we have not really improved accordions nearly as much as we should have.  Maybe technology is our problem. ::)

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Re: Reed Block Acoustics
« Reply #30 on: February 18, 2012, 06:06:19 PM »



I think the problem is that *nobody* knows all the answers for free-reed instruments, there's been far too little serious investigative work (as opposed to anecdotes or opinions) done on them to see what really affects the sound -- or at least, that has been published so people know about it...

That's true, we all just guess based on our ideas and our own experiences, and it's so hard to experiment because of the huge amount of time it takes to build the components.  What has always amazed me is how efficient and well thought out turn of the century accordions were considering how new the concept was.  Taking into account technology and improved materials, we have not really improved accordions nearly as much as we should have.  Maybe technology is our problem. ::)

Maybe it's perfect already  :P

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Re: Reed Block Acoustics
« Reply #31 on: February 18, 2012, 06:41:45 PM »

... and to throw another spanner in the works, we're dealing with human perceptions.

We all blithley go along thinking that we "hear sound" when in fact this is a creation of the human brain interpreting reactions from parts of the body. The interpretation is also acclimitised to particular experiences and the environment. People brought up using different languages will even hear human speech differently with one group completely unable to differentiate certain sounds that are plainly separate for another group.

This is not to say that things are unknowable, and I'm not throwing in a bit of "woo" to say that science is meaningless, far from it. But if anyone thinks that you can simply wave a sound pressure meter and an osciloscope at a melodeon and come up with a definitve answer then I think they are misguided.

Psycho-acoustics I think it's called.

Nobody said you should only use measurements, though these help if you know what you're looking for. For example it's easy to tell louder from quieter, or brighter from softer tone. But what you want to know is what people prefer.

So you try out different things and compare them using a panel of listeners and see which they like best. So long as this is done in an unbiased way, you then *are* finding out what people want to listen to -- it's science, but based on perception.

As was pointed out, the problem is the amount of time and effort to do all this. Just trying few different things for a melodeon would take an entire thesis i.e. several years of work, and for no money. This kind of investigation has been done with various aspects of violins on several occasions, but there's no university department specialising in the acoustics of melodeons :-(
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Re: Reed Block Acoustics
« Reply #32 on: February 18, 2012, 07:41:27 PM »

It would be interesting to see the airflow in various settings of reeds/blocks/hole size/shape etc can't you set some thing up ukebert, you know Slow mo camera, glass sided chambers, smoke machine, etc, a wind tunnel for free reeds or maybe this is taking the science to far and we could just enjoy the results we already have! Does advanced tech equal better? springs on valves allow faster sounding reeds and yet a lot of people condemn fast playing, squeezing in more voices mean upright blocks but flat mounted reeds (Preciosa Lilly Cajun) are louder for less reeds whats a worthy advance and whats more for the sake of more, not forgetting that this seems to be the age we are living in and does the way a reed is ground provide a surface for the air to pick up on and should reeds be ground differently dependant on the intended mounting position flat/upright and angle of input of airflow. I'm sure many of our minds rattle with the unanswered ponderables I know mine does. We need more definitive answers from the scientific community else we all perish from the weight of it all. Personally as interested as I am in all this (I am I am) I'm also entirely happy with the accumulated knowledge and its practical application carried out by that little community in Italy and all the other makers of the world that use their base of knowledge (and parts) and not forgeting the Germans how could one forget the germans and the wonderful work they did spreading the squeeze box to remote places like Brazil, Argentina, Africa, etc, etc, not least our own fondness for their product, but dam those Chinese, who do they think they are the liberty ! Oh yeah they invented it that's right  ;D does any one know of a Japanese produced box ? be interesting if they got involved look what they did with the guitar not to mention their crotch rockets. All in good spirit, All the Best mory
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Re: Reed Block Acoustics
« Reply #33 on: February 18, 2012, 08:24:35 PM »

... and to throw another spanner in the works, we're dealing with human perceptions.

We all blithley go along thinking that we "hear sound" when in fact this is a creation of the human brain interpreting reactions from parts of the body. The interpretation is also acclimitised to particular experiences and the environment. People brought up using different languages will even hear human speech differently with one group completely unable to differentiate certain sounds that are plainly separate for another group.

This is not to say that things are unknowable, and I'm not throwing in a bit of "woo" to say that science is meaningless, far from it. But if anyone thinks that you can simply wave a sound pressure meter and an osciloscope at a melodeon and come up with a definitve answer then I think they are misguided.

Psycho-acoustics I think it's called.

Nobody said you should only use measurements, though these help if you know what you're looking for. For example it's easy to tell louder from quieter, or brighter from softer tone. But what you want to know is what people prefer.

So you try out different things and compare them using a panel of listeners and see which they like best. So long as this is done in an unbiased way, you then *are* finding out what people want to listen to -- it's science, but based on perception.

As was pointed out, the problem is the amount of time and effort to do all this. Just trying few different things for a melodeon would take an entire thesis i.e. several years of work, and for no money. This kind of investigation has been done with various aspects of violins on several occasions, but there's no university department specialising in the acoustics of melodeons :-(

No disagreements here, it would indeed be science. My point was on the anec... no, actually, I'll stop there  :-X

There's a level or point at which all this merely becomes speculation on anecdotal speculations and you have to say "meh, I'll wait for the peer reviewed paper, thanks" (which as you point out, may take a while  :( ).

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Re: Reed Block Acoustics
« Reply #34 on: February 18, 2012, 09:26:22 PM »

While I don't have the equipment to do it, I don't think that we're talking about that complicated an experiment.

We're measuring sound right?  Not whether we like it or not, but whether it changes? So we need measuring equipment, no problem in an acoustic lab, a bellows system (motorised so as to be consistent), one reed and a variety of reed blocks/fixing systems compatible with that reed.  One set of measurements for each of the different reed blocks, one set of measurements for each fixing method with each reed block.  There will either be a difference than can be measured or not.

Second or maybe third year degree project stuff.

Steve
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Owen Woods

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Re: Reed Block Acoustics
« Reply #35 on: February 19, 2012, 01:39:32 AM »

Exactly what I meant -- almost all the pressure drop will be across the reed, what seems to matter most for sound is clean air flow -- especially to the tip of the reed where most of the air flows -- and least obstruction in the air path.

Glad to know that we are in accord :P What I don't know is the exact affect of this clean flow on the sound. I mean, I know what it does in a hand-wavey way, but none of this is backed up by experiment yet.

As was pointed out, the problem is the amount of time and effort to do all this. Just trying few different things for a melodeon would take an entire thesis i.e. several years of work, and for no money. This kind of investigation has been done with various aspects of violins on several occasions, but there's no university department specialising in the acoustics of melodeons :-(

I dunno, looking at the difference between flat mounted reeds and blocked reeds would make quite a nice 4th year project, I have a friend (as previously stated) who is doing something very similar, just with a different  sound generation mechanism. So it could be split into more manageable chunks than the years that it would take to look at the whole picture. Your point about the money is well founded though :P And I think that the Engineering Department at Cambridge would be really interested and I even know of two contacts who between them could make it happen, but self-funded. If I wasn't so bored of being a student and was good enough to do it then I'd be tempted. As it is I just want to get out of that place :P

It would be interesting to see the airflow in various settings of reeds/blocks/hole size/shape etc can't you set some thing up ukebert, you know Slow mo camera, glass sided chambers, smoke machine, etc, a wind tunnel for free reeds or maybe this is taking the science to far and we could just enjoy the results we already have!

This was my original idea for my fourth year project and I talked to some people in department and the conclusion was that it would be a really interesting MPhil project but too complicated and expensive for a fourth year project. Flow visualisation, if you want it done properly, is expensive, there is no getting around that. PIV would be the way to do it, but that requires quite a lot of investment in order to set up. Smoke is difficult - a friend of mine filled his lab with smoke and set off the fire alarm three times before giving up. What you can do is get the sound out, get the physical movement of the reed and get the flow in and out. With those bits of data you can draw some important conclusions, but they have to be based on accepted wisdom for what the flow does in the chamber.

While I don't have the equipment to do it, I don't think that we're talking about that complicated an experiment.

We're measuring sound right?  Not whether we like it or not, but whether it changes? So we need measuring equipment, no problem in an acoustic lab, a bellows system (motorised so as to be consistent), one reed and a variety of reed blocks/fixing systems compatible with that reed.  One set of measurements for each of the different reed blocks, one set of measurements for each fixing method with each reed block.  There will either be a difference than can be measured or not.

Second or maybe third year degree project stuff.

It isn't second year or third year, I can tell you that much. It's a taught masters level project, I know, doing one at the moment :P I think you oversimplify things slightly, most significantly in that all of that needs to be built be somebody! The way that research projects work is that the rig is designed in full by the student and then usually built by the technicians, aided by the student. So the student has to be able to design it themselves, which isn't trivial by any means. Building a bellows system is a bit of a nuisance. What I'd do is what my friend did and build a perspex tunnel connected to the pressurised air system in the lab with a valve such that you can precisely control the flow going into the reed chamber. That is a lot simpler than a bellows system. Remember that this needs to be repeatable and you need to eliminate all variables that you can. So just getting a load of reedblocks and testing them is going to prove nothing, they all have different materials, geometries and constructions, there is too much to test. I would make two reed chambers being the same dimensions, the same construction and the same material (would probably 3D print them for repeatability) and the only thing that would be different would be the position of the hole. I'm not sure how I would clamp them, I'd probably put in a flange to screw them down securely. Both flanges would feature on both blocks obviously. I would also have to think about how to secure the reed, probably screwing again, which would probably involve inserts on the blocks. The experiment should probably be carried out in an anechoic chamber, which isn't too difficult, but there is demand for these and you'd have to make your case to whoever is in charge of it. Measuring flow and pressure isn't too bad, nor is controlling it. You'll need a microphone with a flat frequency response and good quality microphones cost a lot of money. But if you have a decent microphone then measuring the sound shouldn't be a problem. You'll also need an amplifier and a junction box to process the data in such a way that your computer can read it. And software to process it, such as MATLAB. If you want to measure the physical movement of the reed then by far the most effective way is through a laser vibrometer. These do not add mass (which obviously changes the pitch of the reed!) and can do multiple scan points extremely quickly. Mine cost department £100,000 but you can get slightly cheaper ones. In fact there is one in the corner of my lab not being used that would be perfect for the job. Then there is flow visualisation, but that would be research masters level and I know little about it except that it is not easy.

And you'd need to do far more than one measurement! First you'd have to do a set with one block and one reed, to check how repeatable the experiment is. Then, assuming that you're getting constant results, you can take it off and dismount the reed, then putting it together and measuring it again. If that works then you try on different days and at different ambient conditions. That is all useful data. If you get the same results then you know that things are good. You then repeat that with the other block. Then you'd have to measure the sound out for each block at a range of different flow rates, repeating each experiment a number of times so as to be sure that you are getting a representative sample. It will be tricky to set up the system so that it measures transients well, so that will take a while to get right. You'll then need to measure the physical movement of the reed using the vibrometer, again at lots of different flow rates. You'd be taking a lot of data off the system and things are going to go wrong, so you'll have to repeat whole batches of experiments once you realise that you haven't taken something into account. There will be some days where you get no data at all, there will be some days where the system just will not work. It will take months of effort just to get the initial results. And once you have the results then you have to analyse them and no matter how straightforward this seems it will take forever. This is called "research". It is an art and I am finding out to my cost that it is not easy!

So it isn't a complicated experiment, but even a simple experiment has a lot of things that need to be thought about. Take my friend. He is academically and practically brilliant, he got a first in his bachelors and is a decent machinist. He is exactly the sort of person who does very well in research. He is aiming to do something very similar using similar kit. It took him a month and a half to get decent data, it's now 4 months into the project and he thinks that he has some results. He still has to do a fair bit and he'll probably finish doing his analysis at the 5 month mark. Then he'll write up, which will take about a month. So it's a good 6 months work, spending about 25 hours a week in the lab, so working around other work (as this is only worth half of the masters). And that would be to just test the difference between flat mounting and block mounting. If you want to look at the effect of the cassotto, or tapering or material or construction or different reeds or plate materials or any of the other things that we've discussed then you'll need to build a new experiment and start over again. So whilst you can make a nice 4th year project out of some of this, a nice MPhil project out of other parts, you won't be able to cover everything except in a PhD.

p.s. forgot to mention that my friend designed his rig last July and got it built over the summer so that he could start work at the beginning of the year, so that isn't included in the 6 months.
« Last Edit: February 19, 2012, 01:43:40 AM by ukebert »
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Owen Woods

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Re: Reed Block Acoustics
« Reply #36 on: February 19, 2012, 02:01:05 AM »

p.p.s. People may be interested in this guide to amateur experimentation written for musical instrument makers by my supervisor: http://www2.eng.cam.ac.uk/~jw12/JW%20PDFs/Notes%20on%20acoustical%20measurement.pdf
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Re: Reed Block Acoustics
« Reply #37 on: February 19, 2012, 03:20:47 AM »

This thread is most interesting to me as I have started an Open University Technology of Music Course and this discussion seems in point.  I shall bookmark it and return to it when (if) I learn something from the course.

Oh good - you're going to come back and tell us all the answers  ;)

I note all that you write.  I shouldn't be so arrogant as to be welcomed on to a site and then flood it with opinions.

There are some people on this thread with very evident knowledge in the matter of sound technology as well as in music and I am in a learning situation on both counts.  I had hoped to see whether I could perhaps look at melodeon sound as a project of my course if the opportunity arose.
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blafleur

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Re: Reed Block Acoustics
« Reply #38 on: February 19, 2012, 11:59:36 AM »

But opinions is all any of us really have, actually it's more theories with a few opinions thrown in. ;D

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Re: Reed Block Acoustics
« Reply #39 on: February 19, 2012, 12:05:03 PM »

A couple of comments on Ukebert's post -- most of which -- as an engineer knowing the Eng Lab at Cambridge very well -- I agree with :-)

Simulating the air flow sounds easy, but whether it can be done in a sensible amount of computing time is the issue. According to the simulation software manufacturers their software is perfectly capable of simulating the chips we're designing, but to do this in enough detail would take years of real time (on a 128-CPU cluster) to get useful results; if you simplify the simulation to the point where it runs in useful time, you discard exactly the details that you're looking for. It's the kind of scale of problem that jet engine manufacturers have to deal with, and they have rather large budgets (both time, effort, money and supercomputers). Maybe if I could get access to the Fujitsu K supercomputer ('cos I know the engineers who designed it, in fact I met them last week at an award ceremony in Japan) this could be overcome, but I somehow think the Japanese government has first call on it...

So you're down to building stuff and measuring/listening to it. You don't need an anechoic chamber for free-reed measurements, a cardioid mic placed a few inches away will reject room reflections almost completely. But you do need someone to spend a lot of time building stuff with different materials/construction and this is where the time/effort would go; compared to this doing the measurements is easy.

Also doing anything significantly different in reed/frame construction in particular is a lot of work, the machinery is built to make standard reeds in standard frames so anything else has to be either done by hand (the old way) or using CAD/CAM machining (the new way). If I remember correctly there was one paper only about a new way of making high-frequency reeds with better volume and tone by shaping the reed and/or frame, and just this was a 3-year PhD.

I'd love all this to happen and be taken seriously but it would need a university engineering department to drive it, and multiple postgraduate students to work on it over several years. Anyone know any suitable heads of department who play melodeon?

Ian
« Last Edit: February 19, 2012, 12:07:41 PM by IanD »
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