ACOUSTICAL WOODS FOR THE LOVE FLUTE

By David Osborn

Wood – the Most Natural and Most Traditional Material for Flutes
Although flutes have been made from just about any material imaginable, since the most ancient, primitive days of humankind, the most natural and traditional material for making flutes from has always been wood of various kinds.  In fact, so close is the association of flutes and other wind instruments with wood that the whole category of wind instruments has usually been called woodwinds.  There is something about the natural, organic cellular structure and grain patterns of wood as a living, growing thing and the music created by a wooden flute, which has always had associations with the pastoral life and the world of Nature.  In fact, until Theobald Boehm, the inventor of the modern flute, started making flutes from precious metals like silver and gold in the mid nineteenth century, flutes had for many centuries always been made from wood.  Nevertheless, if one goes back far enough in the history of flutes in the Americas and the New World, one finds flutes made from clay and condor bones as well as the more common wood, cane and reed. 

The only essential qualities that a material absolutely needs to have in order to have flutes made from it is enough solidity and dimensional stability to be able to house or encapsulate an air column, sound window and blowing edge of precise, stable dimensions.  However, it goes without saying that some hard, solid materials are much more acoustically desirable than others.  Within the wide world of wood, for example, woods that have desirable acoustical and musical qualities have come to be called tone woods.  Luthiers, or the makers of guitars and other string instruments, have their preferred tone woods; in most cases, these same tone woods can be used for making the Love Flute as well.  Other tone woods might, for various reasons, be more preferable for making flutes from but not so desirable for making string instruments from.  Nevertheless, a lot can be learned by the flute maker about tone woods from the study of making other musical instruments, like string instruments, and a particular wood resonates with a certain sound or tone, whether it is used for making a flute or a guitar, with the same acoustical principles applying throughout. 

The Basic Parameters of Acoustical Woods for the Love Flute
The whole phenomenon of timbre or tone color is indeed an elusive thing, and many different words have been used to describe it.  To give you an idea of just how elusive and abstract the whole phenomenon of tone color is, most, if not all, of the words used to describe it draw allusions or parallels to other dimensions of experience, be they visual, gustatory, tactile or textural, spatial, and so on.  Although many flute makers have expressed the idea that trying to describe a flute wood’s tone color with any degree of precision is absolutely useless and futile, I feel that it may not be so useless or futile as it seems, and that some kind of structured, systematic approach to describing and characterizing tone color can be undertaken.  In trying to describe the elusive phenomenon of tone color among different flute woods, the basic guiding principle that I will use is this: A flute wood’s tone color is a sonic expression of the wood’s grain, texture and other physical properties when taken together as an integrated whole.  This integrated whole is created by the dynamic interplay of various wood qualities and parameters, which I will describe below.    

Perhaps the most fundamental and basic parameter to consider when describing the tone color of a flute wood is the wood’s relative hardness versus softness.  This parameter affects the wood’s tone color more than any other.  Softer woods tend to absorb, transmute or mollify the higher vibrations and overtones of the vibrating air column of a flute; the result is a tone that sounds softer, mellower, warmer or more haunting in nature – such are the words that are commonly used to describe it.  Harder woods, on the other hand, tend to reflect and project these same higher vibrations and overtones, producing a resultant tone that has variously been described as more clear, crisp or brilliant.  The softer woods consist chiefly of the various Cedars and other coniferous woods, as well as the softer hardwoods, such as Alder, Birch, and Poplar.  The harder woods consist chiefly of the harder hardwoods, such as the various Rosewoods, as well as Oak, Hickory, Osage Orange, and the like.  In guitar making, softer woods such as Spruce and Western Red Cedar are used for making the bellies of acoustical guitars, whereas the back and sides are generally made from a harder wood, which tends to reflect and project the sound created by the strings and the soundboard. 

After wood hardness versus softness, the second most important parameter to consider is the relative fineness versus coarseness of a wood’s grain.  Simply put, finer grained woods like Alder, Poplar or Maple tend to produce a sound that is smoother, with a finer, more compact texture to it.  Coarser grained woods like Oak or Mahogany, on the other hand, tend to produce a sound that is a bit rougher in texture, and not so smooth – or you might want to characterize the sound of a coarse grained wood as being a little rough or fuzzy. 

Closely related to a wood’s fineness versus coarseness is its relative density, with the main polarity being between light versus heavy woods.  Woods with a higher specific gravity number are heavier, whereas those with a lower specific gravity number are lighter.  Generally speaking, lighter woods like Pine or Spruce tend to produce a sound that is brighter and more vibrant because, being lighter, they are more easily set into vibration by the pressure of the player’s breath.  Heavier woods, like Poplar or Walnut, on the other hand, produce a sound that is darker and denser in nature.
Another interesting aspect of a wood’s grain is its relative porosity, or lack thereof.  A wood’s porosity can most easily be checked by looking at its endgrain; if many small pores are visible, then the wood is very porous.  Porosity in a wood, I feel, creates space and depth in its sound; deep or hollow sounding might be key words used to describe it.  A good example of a porous wood is Oak. 

Another wood characteristic that is a reliable indicator of a wood’s acoustical performance is its relative level of resilience, which is measured by its elastic modulus.  Generally speaking, acoustical woods tend to have a high resiliency rating and an elastic modulus that is quite high – 1 to 1.5 million on the scale, with 2 million being exceptionally high.  Just think - when you release an arrow from an archery bow, it sings out with a musical twang; therefore, if you can make a good bow from a wood, you can also make a good flute from it as well.  As for the particular sonic quality that is imparted by resiliency, I feel that it is a certain vigor and aliveness – or resiliency – to the tone.  Although most acoustical woods have a fair to high degree of innate resiliency, certain woods, such as Hickory and Osage Orange, which have been used to make archery bows, are especially high in this regard. 

The final parameter I wish to consider, which I feel plays a vitally important role in determining a wood’s overall tone color and sound quality, is its botanical family affiliation.  For example, many members of the Fabaceae or Pea family have been used as acoustical woods for making the Love Flute, both for their aesthetic virtues as well as their tone quality and sound.  The many members of this family that have been used for making the Love Flute include Black Locust, Carob, Honey Locust, Koa, Mesquite and the various Rosewoods of the Dalbergia genus.  Listen to video recordings up on YouTube of flutes made from these woods – are you able to discern the sonic family resemblance between them?  In the case of the Pea family woods, I feel it is a certain kind of crispness and definition, almost to the point of being a little wispy.  The crispness and definition of the Fabaceae sound come through more clearly in the harder members of the family, such as the Rosewoods and Locusts, but is not so pronounced in the softer members of the family, like Koa, which are mellower in tone – naturally, there is considerable variation within the family, for all its members are not identical.
Below, I have put together a little chart showing the major botanical families of trees and their woods that are used for making flutes.  First, we start with the soft coniferous or evergreen woods, of which two major families are represented:
Cupressaceae (Cypress family) – Alaskan Yellow Cedar, Alligator Juniper, Cypress, Eastern Red Cedar, Redwood, Western Red Cedar
Pinaceae (Pine family) – Cedar (True Cedars, genus Cedrus), Deodara, Douglas Fir, Fir, Pinon Pine, Ponderosa Pine, other Pines, Spruce
Next come the various botanical families of broad leafed hardwood trees, with some of them being softer, and some harder in the relative hardness of their wood:
Betulaceae (Birch family) – Alder, Birch
Fabaceae (Pea family) – African Blackwood, Black Locust, Carob, Cocobolo, Grenadilla, Honey Locust, Koa, Mesquite, Rosewoods, etc…
Juglandaceae (Walnut family) – Black Walnut, Hickory, Pecan
Poaceae (Cereal Grass family) – Bamboo, Black Bamboo, Golden Bamboo, Madake / Moso Bamboo, River Cane, Tonkin Bamboo, etc…
Rosaceae (Rose family) – Apple, Apricot, Cherry, Pear, Plum, Rowan
Salicaceae (Willow family) – Aspen, Cottonwood, Poplar, Willow
There you have it – most of the acoustical woods that are most commonly used for making the Love Flute, and other flutes, fall within only a few major botanical phyla, or families.     

Comparing and Contrasting Acoustical Woods for the Love Flute
A good way to get a handle on different woods and their acoustical tone qualities is to put woods within a group of similar tone qualities and compare and contrast the different woods within that tonal group.  These groupings of woods that are similar in their tonal qualities occurs mostly along lines of botanical family relationships, although woods of similar grain, texture and physical properties can also be grouped together for comparison and contrast. 

Perhaps the most basic and iconic of wood groups for the Love Flute is the Cedar Group, which is centered around Aromatic Red Cedar / Eastern Red Cedar as the most iconic wood for making the Love Flute.  Botanically speaking, this group encompasses woods that are in the larger Cypress family, or Cupressaceae, which includes the Junipers, commonly called Cedar by Native Americans, as well as other related woods.  Common members of this family, besides Aromatic Red Cedar, are Alaskan Yellow Cedar, Western Red Cedar and Alligator Juniper.  The most distinctive thing about Aromatic Red Cedar’s tone quality is the shimmering edge that it has to its sound, which is kind of kazoo-like, or even reminiscent of the sound of the Chinese Di-Zi, in which the shimmering edge is created by a tightly stretched inner Bamboo membrane.  The shimmering edge is most pronounced in Aromatic Red Cedar, and softer and mellower in Alaskan Yellow Cedar, which is generally more mellow throughout, being a softer wood.  Of the various Cedars, Western Red Cedar is probably the plainest in its tonal quality, with the least amount of edge to it, with the warmest, most mellow sound of them all. 

The other big group among the coniferous woods could be called the Pine Group, which consist primarily of members of the larger Pine family, or Pinaceae.  The thing about Pine is its lightness, which produces a sweet, light and vibrant tone.  Members of this wood group include Douglas Fir, true Firs, true Cedars of the genus Cedrus, and your various varieties of Pine.  The sound is simple, sweet and light. 

Next are the woods whose tone has a high level of gloss or polish to it; not surprisingly, these are woods of medium hardness with a fine grain structure, which include not only your various Maples, but also softer Maples like Box Elder, as well as Cherry and Sycamore.  Of all of the woods just named, Sycamore probably has the highest level of gloss or polish to its tone, followed by Maple.  The mellowest sounding wood of this group is also the softest, which is Box Elder, which is actually a soft species of Maple, being of the same Acer genus.  Besides Cherry, other woods of the Rose family that are of medium hardness and a fine grain structure could also be thrown into this group, such as Pear, Apple and Apricot woods. 

There are two phyla or larger botanical families of softer hardwoods that bear many similarities when it comes to their tone colors – so much so that they could be lumped together into one group.  Besides their relative softness, woods from these two families – the Betulaceae or Birch family, as well as the Salicaceae, or Willow family, are also fine and smooth in their grain structure.  Not surprisingly, the sounds produced by these woods are incredibly smooth, round and full bodied, in addition to being soft and mellow, being velvet-like in their overall sound texture.  Members of this group include Alder, Aspen, Birch, Cottonwood, Elm, and Poplar, not to mention Willow as well.  Although it is of a different family, the Hemp family, Hackberry could be put into this sonic group as well, since its tone is so similar. 

There are also woods that are known primarily for their dense, dark tone quality, which could be likened to that of thick honey or blackstrap molasses.  Black Walnut is a good example of just such a wood, with Black Limba, Koa, Mesquite and Carob wood being other possible members of this group as well. 
I know that what I have presented so far regarding the tonal qualities and colors of various woods is but a beginning; it is a work that I hope other flute makers will pursue even further.  What I have tried to do here is to present a few broad parameters or vectors of tone quality to define the field, so to speak.  You might want to think of it as an initial scaffolding or framework onto which more detailed information regarding the tone qualities of various woods can be fitted later on.  General considerations of tone quality differences between one type of wood and another are one thing; particular considerations of the tone quality of a particular piece of wood as opposed to another piece of the same kind of wood must also be considered in choosing the best wood for your next flute.  I firmly believe in the value of tapping a piece of wood with my knuckles to test its tone quality when selecting it in the lumber yard. 

Other Qualities to Consider in Selecting a Flute Wood
As a musician, I value the acoustical properties of a flute wood above any other; that is why I have put this consideration first in my discussion of acoustical woods for making the Love Flute.  But other qualities and considerations for selecting a wood may also enter the picture, particularly for those who are not, strictly speaking, musicians by nature.  After tone quality, perhaps the next most valued quality in a wood is its visual aesthetics; regarding this dimension or vector, a wood may be rated either as superior, plain or variable, with some pieces being more attractive and others much less so.  Workability is also another big consideration, especially for the flute maker; in addition to being generally more easy or difficult to work, different woods can also vary greatly in the ease or difficulty of performing various woodworking operations on them.  Durability and resistance to moisture and rot is another desirable quality to have in a wood, with Cedars and other coniferous woods, with their protective aromatic essential oils and oleoresins being chiefly responsible. 

Where Nature is lacking in some of these other qualities and considerations, the skill and artifice of the craftsperson can do a lot to supplement or shore up what Nature did not put into the wood.  If a particular wood is a drab “plain Jane” when it comes to aesthetics, for example, there are many remedies that the craftsperson can choose from to enhance the aesthetic desirability of the finished flute.  Ornamentation and inlay work is one obvious remedy, and using a distinctive stain or finish to enhance or deepen the natural beauty and grain texture of the wood may be another.  The same thing goes with the natural durability and resistance of a wood to moisture and rot; the craftsperson has various sealants and protective finishes that he or she can seal the wood with to protect it where Nature herself offers little or no real protection. 

Conclusion: Finding Your Dream Wood
As you progress in your skill and experience as a flute maker, you will undoubtedly gravitate towards certain woods, which really capture your fancy, and have qualities that you really value and admire in a wood.  And those dream woods that you happen to gravitate to, with all their various qualities, is just as much a reflection on you yourself and the qualities you cherish and hold dear as anything else.  It all boils down to the whole gestalt of qualities that a wood possesses, both acoustical and otherwise – the whole package, in other words.  As you grow more familiar with a wood by working on it over time, your familiarity with the wood will deepen into intimacy, with subtle qualities of a wood that can scarcely be put into words or explained coming to the fore. 

High end flute makers may gravitate to the super hard, visually stunning exotic and ornamental hardwoods for their art collector clients; other flute makers may simply believe that the harder woods are more efficient at doing what they believe a flute is supposed to do – projecting and reflecting the vibrations of the enclosed air column for a clear, powerful, resonant sound.  Other flute makers, who are more into a mass production business model, may put a premium on overall value in a wood – a good tone quality for a good and economical price.  The particular woods that you will select and prefer as a flute maker will reflect your own particular personal values and business model also.