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The Influence of Wood on Tone

Author: mamanvatsa
Date: 2016-05-05 22:11

http://www.aswltd.com/chresto90jun.htm

From The Director's Desk
Editorial Views and Opinions

The Influence of Wood on Tone
A Perennial Question Reexamined

Perhaps the most frequent questions that we are asked by customers have to do with the influence of one’s choice of wood on the tone of a recorder or other historical woodwind instrument. There seems to be a great deal of misinformation on this particular issue in current circulation, and it is little wonder that so many players are concerned and confused about this topic and its relative importance in the overall scheme of things. Since this issue of Chrestologia features a special sale on Kьng recorders and each model is available in a choice of up to twelve different woods, it would seem to be an excellent time to address ourselves to this topic, if only to forestall dozens of phone calls and messages asking the same questions! Our on-line Antique Sound Workshop catalogue does in fact contain an information bulletin on recorders which devotes a few extremely concise paragraphs to this perennial question, but it would seem appropriate to expand upon that information and examine this controversial subject in some detail.
Back in the 1960’s, several scholarly monographs were published which seemed to conclude, at least to their authors’ satisfaction, that choice of material, be it wood, metal, glass, ivory, plastic, or any other substance has no influence whatsoever on the tone of any musical wind instrument. Any musician, of course, would strongly disagree with those conclusions, as empirical evidence and personal experience have for centuries convinced players and instrument makers otherwise. Since recorders are largely handmade and tonal differences can also be attributed to minute discrepancies in voicing, it might be well first to look at some modern wind instruments, which presumably might show less sample-to-sample variation.

A modern Bцhm system transverse flute made of wood certainly sounds quite different than an identical instrument made of metal and feels very different to the person playing the instrument as well. The differences between a wooden and a metal instrument are enormous and evident to virtually every person within earshot; the wooden flute is warm, mellow, and covered in tone whereas the metal instrument is bright, clear, and edgy. Furthermore, a metal flute made of sterling silver sounds and feels demonstrably different than one made of gold or platinum or nickel silver. A gold flute is darker; warmer, and more covered-sounding, whereas a silver flute is lighter and brighter. Interchanging headjoints of different materials on the same flute body can also make a substantial difference in tone, projection, and response; and many flutists spend a lifetime experimenting with different instruments and headjoints in an effort to achieve optimum performance.

In the eighteenth and nineteenth centuries, flutes, oboes, and clarinets were usually made of boxwood and much less frequently of rosewood. As orchestras became larger and louder, woodwind makers gradually changed over to grenadilla, which provides a louder tone and greater projection. Many flute makers as late as the early twentieth century were still using grenadilla or ebony but most eventually changed to all-metal construction. Some modern oboe makers still offer rosewood as an alternative to grenadilla, although the great majority of players have a clear preference for the latter. Clarinets seem to be available at the present time only in grenadilla wood, with orchestral projection being the primary concern for makers and players. [Editor's note: rosewood clarinets have just recently experienced a modest renaissance among a few players.

Modern brasswind instruments also show substantial tonal differences due to materials: trumpets, horns, and trombones made of normal or yellow brass are brighter and lighter in tone with more overtone development, whereas instruments of gold brass, an alloy which typically has just slightly more copper in its composition than yellow brass, are darker and heavier in tone, have greater resistance and are more tiring to play, but afford more projection. Nickel silver or German silver, another alloy which in spite of its name has no silver content at all, is heavier still and even more resistant. It is not uncommon among brass instrument makers to make the body of an instrument from yellow brass and the bell branch of gold brass or nickel silver (in the latter case the entire instrument is usually silverplated) to increase resistance and projection.

Organ pipes are an excellent laboratory in which to study wind instrument acoustics, as they are virtually player-independent and have only to produce a single note from each pipe, therefore eliminating the complications caused in woodwind and brasswind instruments by toneholes, keys, bends, valves, and the like. One can build and voice three identical ranks of wooden flue pipes, one of mahogany, one of pine, and one of oak, and readily determine that the lightest and least dense mahogany rank has the weakest and most diffuse tone, the pine pipes a somewhat stronger tone, and the oak pipes the strongest and most compact tone.

Why, then, did so much research a quarter century ago seem to indicate that material plays no part in the tonal spectrum of an instrument? Scientists, using the relatively primitive computers of that time, performed extensive real time spectral analysis of the tones produced by a wide variety of musical instruments and plotted and compared the relative strength of the various overtones. The tacit but incorrect assumption was that the tone of musical instrument was determined solely by its overtone structure (i.e., the presence and relative strength of the various partials) and that what they measured was what one heard. We are now beginning to understand that what they measured was not incorrect but simply incomplete. The comparison of the overtone structure of musical instruments or electronically generated tones can be instructive, but it is only part of the puzzle. When considered in isolation from other more elusive tonal parameters, the investigation of overtone structure can and in fact did lead to misleading information and incorrect theses.

In the interim the science of psychoacoustics, still in its infancy but then largely unknown or ignored, has made some progress toward determining exactly what creates the identification and subjective evaluation of musical instrument tone. In particular, we have learned that attack transients, relatively weak overtones and noise partials (inharmonics) which are present at the very beginning of a musical tone but attenuate quickly, provide important but still incompletely understood psychological cues to the human ear and brain. Experiment has shown that, if a musical instrument tone is recorded and the beginning of the tone is snipped off, the listener becomes disoriented and easily confuses one instrument with another.

Again, pipe organs provide a useful case in point. Classic mechanical action organs, in which the strength and duration of attack transients (usually referred to as “chiff” in organ parlance) are directly controlled by the player's touch, are clearly much more interesting, articulate, and inherently musical than electrical action organs, in which the key is merely a switch turning a pipe on or off and the attack transients are beyond the control of the performer. In the late nineteenth century, when electric action organs came into being, builders experimented with a wide variety of new pipe designs, voicing techniques, and higher wind pressures in a largely futile attempt to compensate for the lack of articulation and musical interest inherent in electrical action instruments. The American theater organ was the ultimate result of this blind alley of organ development, attempting with its enormous variety of stops and sheer volume to make up for its dullness of speech.

It may be seen, then, that the choice of wood does indeed have a definite and predictable influence on tone, although we are only now beginning to understand how to measure and interpret those differences. To be sure, the overall bore, windway design, and the voicing of the individual instrument are far more important factors in the tonal structure of an instrument; it is only when all other parameters are constant that the difference in material comes into any degree of importance. My guess is that, both with recorders and organ pipes, the material is about 10% of the total tonal determinant, the scale and bore another 10%, and the remaining 80% is due to voicing. Our readers may recall from their school days the essence of the scientific method: one should change only one variable at a time. To compare two different makes or models of instrument and two different woods at the same time is folly. Even comparing two instruments of identical construction but differing woods can be misleading, since the tonal differences could well be a product of sample-to-sample variation as well as the result of the woods in question. It is only when one tries out ten or a dozen samples of each model and wood and eliminates the individual sample differences that one can begin to perceive the “distilled essence" of the tone of each It is only then possible to speak of pearwood or palisander as having particular indigenous tonal properties which are independent of an instrument’s tonal design and directly attributable to the wood itself.

The influence of the wood, as we have stated on previous occasions, is due not to the hardness or density of the wood per se, as is generally believed, but rather to the fiber structure and porosity, which determine the relative roughness or smoothness of the bore. In general, softer, less dense woods yield a rougher bore surface, which produces a warmer, more covered and diffuse tone. What actually happens is that the larger microscopic pits in the bore trap the higher overtones or frequencies, which have shorter wavelengths, causing them to reflect back upon themselves and producing some out-of-phase cancellation or attenuation. Harder and denser woods, on the other hand, permit a smoother, more highly polished bore surface and produce a brighter, clearer, and more centered tone quality with greater projection. The reflectivity of the higher frequencies, together with less cancellation and more reinforcement of the upper overtones, produces a more lively, assertive tone quality.

A good rule of thumb as regards the cost and tonal quality of the various woods used in woodwind instrument making is that the softer domestic European woods, being plentiful and near at hand, are less expensive, the imported tropical or exotic woods from South America and Africa are harder and more expensive, and the cost of the wood therefore usually increases with hardness. There are, however, two exceptions to this rule: olivewood and European boxwood are relatively soft woods but, because of their slow growth and rarity, are more expensive than some harder woods.

The softest and warmest-sounding woods are the domestic European fruitwoods: pearwood, plumwood, cherrywood and olivewood. Pearwood is the most gentle-toned and covered-sounding of these four, whereas the other three have a slight trace of brightness, particularly evident after break-in, around a softer core tone. Recorders and other woodwind instruments made from these fruitwoods are usually the best for ensemble performance, since they are relatively self-effacing and blend well with other instruments. Instruments made of maple are somewhat fuller and louder, slightly windy and less re?ned than any of the fruitwocds. Since maple is essentially white and has little grain, many makers stain their maple instruments a medium or dark brown. Staining of pearwood instruments is also occasionally found, although most customers seem to prefer natural unstained instruments. Fruitwood instruments, incidentally, seem to become brighter with use over a period of years, whereas maple instruments, after the initial break-in period, apparently do not.

Most recorder makers have a line of student instruments made from either maple or pearwood as their least expensive offerings. Instruments made from maple or any of the fruitwoods are usually impregnated with paraffin under pressure, in order to stabilize their dimensions and render them impervious to moisture and less susceptible to changes in ambient humidity. Student instruments made of these woods are not only relatively inexpensive but also require very little care, since they do not have to be either oiled or humidified. These softer woods, however, can be somewhat prone to fungus and mildew if they are put away wet in a closed box. This is not a widespread problem throughout most of the United States and Canada, but it is a real concern in our Gulf Coast states and in much of Europe, where the relative humidity levels are consistently higher. Since woodrot and related disorders are extremely difficult to arrest once established, prevention is the best policy. Instruments made of these woods should be allowed to dry out thoroughly before being placed in a closed container.

Boxwood is a popular term for a variety of woods from many different countries which have very little in common except for their pale yellow color. The boxwood used by 18th century makers was either European or the closely-related Turkish boxwood, prized for its relative hardness, bright tonal quality, and natural resistance to water. This wood is only occasionally used for instrument making today: it is usually found as a hedge, takes many years to grow to tree size and is rarely found in pieces large and straight enough from which to fashion a musical instrument. In addition to its rarity and high cost, it often has many small knot holes which are not apparent to the instrument maker until after he/she has had the wood for several years in storage and begins to turn the instrument. Many pieces of boxwood are therefore found unsuitable during the manufacturing pieces and must be thrown away. Many others must be doctored up by filling the knotholes with a mixture of epoxy and wood dust to make them more esthetically attractive and saleable. A further unattractive aspect of European and Turkish boxwood is that it tends to warp very readily as it ages; this is why so many boxwood instruments in museum collections are bent like boomerangs. Given the high fatality rate as well as the cost and rarity of the wood, it is little wonder that recorders and other woodwind instruments made from true European or Turkish boxwood command a very high price indeed.

Some American makers have used so-called Thailand boxwood or other tropical woods of yellowish color as substitutes for true boxwood, with only moderately successful results. Most instruments from European makers labeled as boxwood are in fact made from a South American (usually Venezuelan) wood known variously as Maracaibo or Zapatero, which is plentiful and inexpensive, easy to work, highly stable, but somewhat blander in tonal properties than European boxwood. It is also considerably less hard and dense and less water-resistant as well. Some makers choose to paraffinize this wood and others don’t. South American boxwood is intermediate in cost and tonal quality between the domestic fruitwoods on one hand and the exotic tropical rosewoods on the other.

A fairly reliable guide to the true origin of a boxwood instrument may be ascertained from its price: if a boxwood instrument is found among a maker's medium-priced instruments, such as those made of bubinga, you be reasonably certain that it is Venezuelan boxwood; if a boxwood instrument is among the most expensive models, surpassing even grenadilla and price, you may be certain that it is made of genuine European or Turkish boxwood and is the real McCoy. Instruments of South American boxwood are tonally neutral and transparent and reflect more the voicing and design of the instrument than any specific tonal property attributable to the wood itself. When customers wish to compare different makes and models of instruments, we advise them to try one of each model in Venezuelan boxwood, since the true character of the design, relatively uninfluenced by the wood, will be easier to perceive in that context. Euro-boxwood, on the other hand, produces instruments which are brilliant, edgy, and ostensibly solo instruments of considerable character and strength. The few makers that offer instruments made of this wood, such as Fehr and Huber, charge a princely sum for them; and the availability of such instruments is usually extremely limited.

Other medium-priced tropical hardwoods such as bubinga, padouk, hornwood, and zebrawood are somewhat harder and denser than boxwood, maple, or any of the above-discussed fruitwoods. They are more striking in color and grain and offer greater volume, projection, presence, and character than any of the softer woods. Bubinga, often called. African rosewood, is reddish-brown and a good middle-of-the-road choice for both solo and ensemble playing, being full and well-focused and neither too bright nor too dark. It is, however, somewhat allergenic and not recommended for players with a tendency toward skin allergies. Padouk, from the Andaman Islands in the Indian Ocean, is an intense dark red or reddish-purple in color, is much lighter in weight than the other hardwoods (a property which is especially welcome in tenor and larger sizes), and has a clear, transparent tone with moderate brightness. Zebrawood is striking and handsome in appearance, with large dark-brown to brown-black stripes on a yellow-brown background. It is more grainy and fibrous than the other woods in this medium price category and is rather burly and somewhat similar to maple in tone quality, although infinitely more interesting in appearance. Hornwood (sometimes called European ironwood) is an extremely hard wood of an interesting but subtle grayish cream color; it produces a dark, strong, neutral tone which is well-centered with good projection.

The hardest woods commonly used in recorder making are from the South American Dalbergia family of rosewoods which includes such Brazilian varieties as palisander, kingwood or violetwood, and tulipwood (in order of increasing hardness and brilliance) and their close cousin grenadilla wood from Africa, often called African blackwood. Palisander varies widely in color and density from a softer, chocolate brown variety to a very hard, light yellow-brown wood, all with highly distinctive brown stripes. Kingwood and violetwood are essentially the same wood, a harder and brighter-sounding variety of palisander with smaller and more varied grain markings and a slight lavender cast which is most attractive. Tulipwood, sometimes called Bahia Rosewood, is the hardest and rarest of the Dalbergia genus, having light to dark red stripes on a yellow or grayish-yellow background, and is easily the most dramatic of all woods in appearance and the most brilliant and vibrant in tone. All of the Brazilian rosewoods have pronounced personalities and make excellent solo instruments, but they are as a result less well suited to consort use.

Grenadilla wood, extremely dark brown to black in appearance and quite heavy in weight, is stronger in tone than the rosewoods but not as edgy or brilliant. It is usually the wood of choice for professional players who must perform in large halls or with modern instruments such as flute, oboe, violin, or piano. It is extremely dense and solid, but relatively inelastic; it can easily crack if dropped or exposed to low temperature or humidity conditions. Ebony, a somewhat softer and coarser wood from Africa or India, is not as satisfactory tonally but is occasionally found as a cheaper grenadilla substitute. It does not cut as smoothly as grenadilla and, in poorer grades, chips easily when bored or turned. The generic term blackwood is used to designate either grenadilla or ebony. The old Arnold Dolmetsch firm referred to its grenadilla recorders as blackwood; some other modern makers label their ebony instruments as blackwood, in an apparent attempt to dupe the customer into thinking he/she is buying a grenadilla wood instrument. In an attempt to foster truth in advertising, our price lists cite the actual wood used, which in some cases differs from the nomenclature used by the maker.

The hardest, heaviest, and most penetrating of woodwind instruments have traditionally been made from ivory, which because of its minute grain structure may be polished to a very high degree. Since the importation of ivory and ivory products has been virtually banned by the U.S. government for more than a decade, a number of synthetic ivory substitutes have been introduced in recent years, most of which are somewhat lighter in weight and less fine-grained than real ivory. Interestingly enough, plastic recorders, in spite of their lighter weight, have tonal properties very similar to ivory. While ivory recorders have a great cachet among collectors and plastic instruments none whatsoever, they both produce a hard-edged, glassy tone that is not terribly subtle or attractive for any extended period of time. They also are extremely prone to clogging, even after a careful break-in period. Ivory recorders make great display pieces, but they are not the most musical of instruments. The ban on ivory instruments seems to have been a blessing to both people and elephants.

In summary, we can conclude that wood choice does have a definite, predictable, and audible influence on the tone of a recorder or other woodwind instrument. The overall design and voicing of the instrument, however, have a much greater influence on the sound than the wood per se. When comparing different makes and models of instruments, it is advisable to try a variety of instruments in one common wood first, in order to determine which design is best suited to your tastes, needs, and budget. Once a particular model has been selected, it is then appropriate to try the various wood choices in which that model is available, in order to refine the tonal properties more closely.

Finally, it is possible to choose a wood which either emphasizes or minimizes the basic tonal design of the instrument; a Kьng recorder in pearwood (a mellow design in a mellow wood) or a Coolsma recorder in palisander (a reedy design in a reedy wood) would be two very different examples of reinforcement of tonal design by wood choice. Alternately, it is possible to mitigate the tonal design by choosing a wood which contradicts the basic nature of the recorder; this often results in the most interesting and complex-sounding instruments: a Kьng recorder in grenadilla or tulipwood is a gentle, warm-toned instrument with enhanced projection and character; whereas a pearwood Roessler Meister or Oberlender recorder would dampen and mellow the essentially bright and edgy nature of these designs. Given the wide variety of woods and models available, it is a delightful challenge for us at ASW to help each and every customer find just the one right instrument for his or her personal taste, needs, and budget – that's why we have over six hundred different models of recorders in stock!

Post Edited (2016-05-05 22:12)