The influence of material on woodwind sound is a perennial topic of discussion amongst players and makers.
Usually the scientists say, ‘Dimensions,’ the players say, ‘But materials matter as well,’ and the scientists say, ‘No, just dimensions.’ As a woodwind-playing ex-scientist I had to try, in self defence, to reconcile the two.
What follows is a summary of the conclusions I have reached and the research they are based on. The research I have quoted refers to flutes but I am confident the results apply equally well to recorders, clarinets, oboes, bassoons and saxophones.
I am quite willing to add to it or change it if anyone can show me more evidence for or against my position: I don't claim infallibility. On the other hand, anecdotal evidence alone is unlikely to change my opinions significantly because I have already accumulated plenty of it in my forty-something years playing recorders, flutes (Boehm and pre-Boehm; metal, plastic and wood), clarinets, saxes and miscellaneous 'ethnic' woodwinds.
Differences between similar woodwind instruments made of different materials come from:
1. Differences in dimensions - bore and tone hole shape, and surface finish (see Fletcher, Coltman). This one is by FAR the most important.
2. Mechanical differences between materials (McGee, Fletcher). This is largely number one in disguise, e.g. if one material is easier to work accurately than another, its dimensions will probably be closer to the design; or if ebony is easier to bring to a high polish than cherry, ebony flutes will tend to have smoother bores.
3. The tendency for makers to put more effort into expensive materials (Fletcher). This is definitely number one in disguise.
4. Preconceptions and wishful thinking (Coltman and Linortner). Players will tend to get out of an instrument what they expect to get out of it.
5. Differences in feedback to the player. The player feels the sound vibrations through fingertips, lips and jaw; and he/she hears sound from embouchure hole (flute) or through the mouthpiece and jaw (reeds) and finger holes in different proportions from anyone further away. I have no idea how this feedback could be studied but as a player I am sure that it has an effect, even if it is mostly psychological -- which would mean it shades off into number four.
The Research on which my conclusions are basedWhat follows is a series of extracts and summaries of research. I have included most of Fletcher’s paper because I don’t think it is widely available. The others are represented by much shorter extracts but are linked to sources of the full items.
Silver, Gold or Platinum?
by Neville Fletcher, Australian National University, Canberra, ACT 0200, Australia, published in The Flute, August 1996.
For most of us these days, a student flute is made of silver-plated metal, a professional flute is made of solid silver, and top soloists play gold flutes. Why is this, and what is the difference, apart from price?
Most woodwind instruments are made of wood, as their name implies, and this was true of most flutes as well until early this century. Wood had the advantages of being inexpensive and easily worked with simple tools, and the dark colour of many timbers produced a nice visual contrast against silver keywork. The timber species used were chosen not so much for appearance, however, as for desirable mechanical properties. A fine straight grain allowed for accurate machining, dimensional stability over the life of the instrument, and a fine polished finish. Chemical stability in the presence of moisture was also of prime importance. African blackwood was, and still is, a highly favoured species, as also are grenadilla, cocus wood, and some other rainforest species.
There has always been argument about the extent to which the material from which the instrument is made affects its tone quality, and we will return to discuss this later, but wood necessarily imposes some limitations on instrument design that have turned out to be important. The prime one is that the tube walls cannot be made very thin, so that there is an appreciable "chimney" at the embouchure hole and around each of the finger holes. The embouchure chimney is very important since, without it, it is nearly impossible to play low notes. The finger-hole chimneys are less important, but do have some effect on tone colour. The musical difference, if any, between different species of wood, however, comes only from the slight difference in roughness of the internal bore, provided the instruments are otherwise identical, though the difference in instrument weight may give a slightly different feel. In this, woodwind instruments are very different from stringed instruments, in which the vibrations of the instrument body determine completely the radiated sound. In a woodwind instrument the tube walls serve simply to define and confine the vibrating air column.
[discussion about metal Boehm flutes deleted]
The idea that the wall material of the flute tube can have an influence on sound quality derives in part from the tradition about wood, but also from some experiments by the physicist Dayton C. Miller early this century. Miller made a double-walled square-section organ pipe from thin sheet metal and progressively filled the space between the walls with water while the pipe was sounding. The sound of the pipe went through marked, and often unpleasant changes, indicating the importance of wall vibrations. Miller, who was a keen flute player and instrument collector – his flute collection is now in the Library of Congress in Washington DC – applied his conclusions to flute making, and proposed that gold is the ideal flute material.
These experiments, however, have little relevance to real flutes, which have cylindrical tubes that are thousands of times stiffer to vibrations than the flat walls of Miller's pipe. Measurements show that radiation from the vibrating tube walls contributes less than one ten-thousandth of the radiated sound, and this is completely inaudible. Indeed other experiments show that listeners are unable to distinguish between the sounds from a flute head-joint connected to tubes of silver, copper or even cardboard! Miller's arguments about gold for flutes were based upon the low speed of sound in gold (because of its high density), though why this was thought desirable is unclear. In fact, any wall vibrations of acoustic importance are transverse (sideways) rather than longitudinal (lengthwise, without changing the shape), and the frequencies of these vibration (or equivalently the speed of transverse waves) increases as the thickness of the tube walls is increased. This can therefore be varied much more effectively by changing wall thickness than by changing the tube material.
Despite all this, different flutes do feel, play, and sound quite different.
What is the reason?
To understand what is probably going on, we need to return to the way in which the flute, and particularly its head joint, is made. The maker takes a length of tubing – cupro-nickel, silver, gold or platinum – places a properly shaped steel mandrel inside, and forces the tube through a hole in a lead block. This deforms the tube so that its shape closely matches the tapered shape of the mandrel. But the match is not exact, for the tube material is elastic and springs back a little, and the extent of this elastic rebound depends on the tube thickness and on the metal from which it is made – a silver head joint will differ slightly from a gold one made on the same mandrel, and even a difference in diameter of a tenth of a millimetre slightly affects the tonal balance of the completed instrument. Then the maker must add the riser chimney and the lip plate, and must finish the embouchure hole by hand – one of the most critical operations to final musical performance. In all there operations there are slight variations in detailed geometry and consequently in final musical performance, and flutes made of one metal do not sound consistently better than those made from another – the variation from one maker to another is much greater, and even nominally identical flutes from one workshop can be detectably different.
So where are we? Should we save up our dollars and buy a gold flute, or be content with an already expensive silver one? The best advice is to try them both and then decide – indeed that advice applies when choosing between nominally identical silver flutes as well. Apart from that, there are some potential advantages on the side of gold. It looks great and does not tarnish, and you can be sure that the maker will have been one of the best craftsmen in the company.
(Most of Fletcher's publications, but not this one, are available from http://www.phys.unsw.edu.au/music/people/fletcher.html
His "Materials for musical instruments", Acoustics Australia 27, 5-9 (1999), available from that site, is also very relevant to the present discussion and is non-technical enough for easy reading.)
Coltman's Concrete Flutes
John W. Coltman, a U.S. physicist, recently demonstrated a concrete flute during a conference on music and human adaptation at Virginia Tech. With their eyes diverted, the attendees could not tell the difference between the concrete flute and a cherrywood one. The flutes were identical in all respects except for the material that enclosed the vibrating air column.
… even though dozens of studies have been done proving Coltman's point, we bring with us beliefs about preciousness and rarity which are hard to give up and have little to do with the facts. Admittedly, the craftspeople working in platinum may be more skilled than those working in copper, but they may not be. The metal or rare woods have nothing to do with the quality of the sound. What is important is the design and workmanship, the exactness of the air column, the thickness of the walls and the shape of the tone holes.
Coltman's published papers can be downloaded from
...refers to Coltman's work in his Flute Myths Exploded at
http://www.mcgee-flutes.com/FluteMyths.htm (scroll down till you see it) and finds good reasons to disagree.
From the very practical viewpoint of an instrument maker, his reasoning makes perfect sense: if he uses one material rather than another, the tonal result will be different in quite predictable ways.
However, I believe it is also possible to see some of the differences he discusses as dimensional differences at the microscopic scale, as Fletcher does. For instance, if surface smoothness is important to the sound, one might be able to make a silver flute sound more like a wooden one by roughening the bore in imitation of wood grain.
Renate Linortner's Thesis
'Silver, Gold, Platinum - and the Sound of the Flute'
(Introduction, Summary and References quoted from that site.)
The role that the wall material plays in determining the tone quality of flutes has long been a subject of argument. Laboratory measurements of sustained tones in artificially blown wind instruments made by J. Backus in the 1960’s [1,2] generally showed no evidence that the wall material has an appreciable effect. But players and instrument makers didn’t accept these results because of the fact that the instruments were artificially blown. Therefore J. W. Coltman worked out an experiment with flutes made of three different materials (silver, copper and wood) and with different wall thickness. They were blown by the author himself and four different professional flutists . The experiment was completed by listening test with 27 observers. The result of statistical analysis was that “no evidence has been found that experienced listeners or trained players can distinguish between flutes . . . whose only difference is the nature and thickness of the wall material of the body, even when the variations in the material and thickness are very marked.” Nevertheless instrument makers, players and listeners continue to insist that the nature of the wall material does indeed have an effect on the instruments’ sound. Perhaps, from the point of view of flutists, there is a stigma attached to J. Coltmansę experiment: the flutes were built especially for this experiment and without any keywork.
To terminate this discussion once and for all (which, as J. Backus pointed out , probably started in early Stone Age circles with assertions that a flute made from a human thigh bone had a much better tone than one made from a stick of bamboo), we chose seven identical flutes made by Muramatsu which only differ in the wall material and could be purchased by everybody ...
The discussion on the influence of the material of wind instruments on the sound color is unending. While acousticians speak mostly of a negligible influence, players are convinced that the material highly influences the color of the radiated sound. This paper reports on experiments done with 7 different flute materials and 110 testpersons, where the price of the instruments is between Ř 3,000.- and Ř 73,000.- (!).
Double blind tests and statistical analysis showed players‘ and listenersęstereotyped ideas on that matter and the non-recognizability of the used material. Sound analysis pointed out big differences in the sound level and sound color of played tones caused by the player and just measurable but not perceivable differences (< 0,5 dB) in sound color caused by the material.
 J. Backus, JASA Vol.36, p. 1881-1887, (1964)
 J. Backus, T.C. Hundley, JASA Vol.39, p. 936-945, (1966)
 J. W. Coltman, JASA Vol.49, p. 520-523, (1971)
 J. Backus, The Acoustical Foundations of Music, p. 208, Norton, New York (1969)
with minor edits (extra ref. for Fletcher) May 2008
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