The Differences Between Metals

    It is a typical scene. You walk into a flute shop and are instantly inundated with a plethora of options, features, bells, and whistles. Besides the multitude of smaller, mechanical options, a large selling point is the material from which the instrument is made.
    Flutes are available in a variety of materials. Since Theobald Boehm’s 1832 reinvention of the flute and now the modern flute system, metal flutes have risen to the top in preference and production. The most common metals used today include nickel silver, silver, coin silver, gold, and platinum. Each metal is advertised to have distinct qualities in sound production.
    Besides the significant differences in cost, does the type of metal used for a flute make a significant difference in sound quality? This is a question that elicits debate from flutists of all kinds – flute makers, professionals, and amateurs.

Side One – It Makes a Difference
    Flutists who take this view think it wise to invest in the best material they can afford because of the positive difference in sound production. Many flute makers and retailers advertise differences in metals. In general the metals are given descriptions like these:

Nickel Silver (“German Silver”) – a combination metal of copper, zinc, and brass. It is commonly used in student models because it is less expensive; the sound quality is  less vibrant than that of silver.
Silver – available in different purities and combinations of other metals; it is responsive and has a bright sound.
Coin Silver (Sterling silver) – 90% silver and alloyed with copper; sound quality is responsive, bright, and lively.
Gold – available in various carats and alloyed combinations. Sound quality is dark or warm.
Platinum – the heaviest and most dense material used. Sound quality is strong, penetrating, bright, harsh.
   
Side Two – No Difference
    Those in this camp see a greater difference between players than between instruments. They do not think that purchasing a flute made out of gold is necessarily going to give the player a warmer, darker sound.
     We asked Patricia George and Donald Peck what they thought. Their views follow below:

Historical Opinions
    This question has been debated for centuries and seems likely to continue to be a topic of discussion. Back in 1752 Johann Joachim Quantz said, “Whoever wishes to have the flute shrill, rough, and generally unpleasant, may have it lined with brass, as some have done.”¹ During Quantz’s time, flutes were typically made of wood, however, ivory, porcelain, and glass were tried as well. In his 1928 treatise, Rockstro reports that they experimented with lining ivory and wooden headjoints with metal. Apparently, Quantz did not find the use of metal agreeable to the ear.
    Top flutists of the past 100 years all have personal preferences and opinions on the matter. Georges Barrère, principle flutist of the New York Symphony in the early 20th century, premiered his platinum flute with Edgard Varèse’s Density 21.5. Barrère preferred his platinum flute the rest of his career.² Marcel Moyse, French flutist and teacher of the mid-20th century, opted for a nickel silver flute for all his performances.³
    Jean-Pierre Rampal, internationally renowned as “The Man with the Golden Flute,” fell in love with his golden Louis Lot flute. Rampal preferred the gold flute justifying his choice by saying, “[it was] a little darker; the color is a little warmer, I like it.”⁴
    William Kincaid, American flutist and teacher, played on a platinum flute from 1939 until his death in 1967. He felt it was superior to silver due to its strong, penetrating sound qualities. It was auctioned off in 1986 for $187,000 – the world’s most expensive flute.⁵ Julius Baker, acclaimed New York flutist and teacher, preferred a sterling silver flute.⁶ Most recently, world-renowned flutist, Sir James Galway has no preference of flute. Galway states his opinion on his website:

     I have never really recommended one metal over another when discussing flutes. The fact is that I cannot tell the difference when I am listening to someone play. This was brought to my attention when I listened to the active participants in my class in Italy playing. They were all really good players, and I suddenly looked up to see Noralee Garcia playing a platinum flute with red gold keys. The first thing that struck me was how good looking the instrument was. I then began to think that if she was playing some other instrument would she sound different?

It seems that even among world-famous flutists there is no consensus on metal.
   
Acoustics
    Sound is “a vibratory disturbance in a material medium which is capable of producing an auditory sensation in the normal ear.”⁷  The flutist blows across the lip plate creating an air jet that splits as it hits the edge of the furthest side of the lip plate.⁸ Only about 20% of the air goes into the flute where it vibrates in the tube and creates sound.
    As the air inside the flute tube vibrates, opening and closing keyholes changes the pressure inside the flute allowing pitches to change.⁹ It is the inside of the flute and how it is shaped that really affects the resonance, which in turn affects the sound production. How well a flute can resonate is what creates a nice tone quality. Flute makers and players are continually looking for better methods, including experimentation with metals, to create a flute that has maximum resonance for the best possible sound.
    Resonance is an important aspect of sound quality. Often it is coupled with harmonics. The more harmonics present in the sound, the more resonant a sound is considered. According to acoustician, Charles Culver, “It would appear that the density of the material and its elasticity are both factors in the case [of producing harmonics]”. If resonance is equated with the production of harmonics, then it is important to look at the density and elasticity of the precious metals used in flutes.
     The table below shows the differences in density and elasticity between sterling silver, gold, and platinum.

     There have been only a handful of scientific studies that have researched and analyzed the different effects metal has on flute sound. Three important experiments were conducted by John Coltman (1970), Joan Lynn White (1980), and Gregor Widholm (2001). 
     John W. Coltman, physicist and amateur flutist, became highly interested in flute acoustics in the 1950s. In 1970 he conducted his famous “Effect of Material on Flute Tone Quality” study. Prior to this time, Coltman found there to be a lack of scientific research concerning the effect material has on flute sound.¹⁰
     He constructed three keyless flutes made of Grenadilla wood, silver, and copper. Each flute had a diameter of 1.9 cm.
       •The silver flute was made out of a piece of stock silver – the same silver professional flute makers use – with a wall thickness of 0.036 cm.
       •The copper flute had a wall thickness of 0.153 cm.
       •The Grenadilla wood was made with a wall thickness of 0.41 cm, the typical dimension of wooden flutes, but weighed 1.7 times as much as the silver.
All three flutes were 32.7 cm long. The headjoints were made from the same mold of Delrin plastic, extending the flutes another 5.1 cm. The mouth hole for each flute had a diameter of 1.75 cm, molded after a professional flute mouth plate.
     After each flute was constructed, “the acoustically important dimensions of all three instruments were thus identical within  .01 cm.”¹¹ To test the quality of these flutes, a sound was made at 398 Hz, approximately G4, with “the ease of sounding, quality, power…judged excellent by those who tried them.”¹²
     The first experiment focused on audience observations. The audience consisted of 27 listeners, 20 of whom were musicians; 13 were flutists (professional and amateur), and 7 had little musical experience and training. Behind a curtain, a flutist played three identical phrases, each phrase with a different keyless flute. The listeners were to note which flute they thought was playing that particular phrase.
     The second experiment focused on the flute player. Coltman wanted to test a player’s discrimination towards flutes. The three flutes, were mounted symmetrically on a plastic shield. The plastic shield separated the player from viewing the body of the flute. The headjoint was the only part of the flute the player saw and touched. A rod parallel to the flutes was placed so the player could hold the rod while they played and not touch the flute bodies, to keep the player unaware of which material he was playing.
     The players were then asked to identify which tone they preferred or material they thought they could identify. The player was then asked to spin the rod and randomly select a flute to play again and try to find the initial preferred tone. Twenty-one players preferred silver, 19 preferred wood, and 14 preferred the copper.
     In his study, Coltman found that neither the trained nor untrained musicians, could correctly “distinguish between flutes of like mouthpiece material whose only difference is the nature and thickness of the wall of material of the body, even when the variations in the material and thickness were very marked.”
     Coltman’s results suggested that the performer makes a greater difference in sound production than the kind of material used in the flute. Coltman interestingly comments, “One player did, correctly, point out that one of the three instruments appeared at first to be slightly flat. This effect is due to high thermal mass of the heavy copper tube, which causes it to warm up more slowly than the others. This is an example of a reason to prefer certain materials for flute construction, and there are many others. Tone quality or ease of response are not, however, one of them.”
     It took nearly 10 years for another study of similar nature to be conducted. Professional flutist and teacher, Joan Lynn White completed her doctoral dissertation, “A Spectral Analysis of the Tones of Five Flutes Constructed by Different Materials” in 1980. In her dissertation, White addresses the pedagogically controversial topic of timbre and flute material. White “systematically analyze[d] the tonal spectra of five modern Boehm-system flutes constructed of different metals…with the same specifications by a single manufacturer”.¹³
     Japanese flute maker, Muramatsu, donated five flutes to White’s research, all from the same flute model series; each flute had the same internal and external measurements. The flutes were in the French style, had a B footjoint, and were as exact in dimensions as they could be. The only varying degree was the metal each flute was made from. White used flutes of white gold, 14kt gold, palladium, and two of sterling silver. Her study focused on the harmonic structure of tones produced on each flute looking at the influence of the wall material, intensity level, frequency level, and the performer.
     The actual experiment consisted of two professional flutists, White and a colleague. They played specified tones at both forte and piano dynamic levels on each flute. The were 392 Hz (G3), 784 Hz (G5), 1568 Hz (G6). Three trials were completed for each frequency and intensity level and were conducted in an anechoic chamber (a specially built soundproof room) with a number of technologies that assisted in collecting sound data.
     White’s findings showed “the tonal spectra of the five flutes differed more in the number and strength of the upper partials than in that of the lower partials present in a tone.” More differences were present when the tone was played at a forte level compared to piano. White commented that “performer variability is evidenced in the visual examination of the data derived from this study.” White also concluded that there is greater difference between performers than materials of flutes. However, she noted, “The objective data derived from this study must be viewed in relation to the intrinsic subjectivity within the realm of aesthetics.”
     In 2001 Austrian professor Gregor Widholm conducted another study.  Widholm obtained seven identical flutes that were identical inside and out in both dimensions and wall thickness. The only difference being the material the walls were made out of. The seven flutes used were silver plated, fully silver, 9kt gold, 14kt gold,  24kt gold, platinum coated, and fully platinum.¹⁴
     Seven professional flutists from the Vienna Orchestra and Vienna Philharmonic created the initial sound data that would be used in a two-part study. Every flutist played on each flute a chromatic three-octave scale, multiple dynamics on A4, F5, D6, and B-flat 6 (crescendo from ppp-fff), a solo from Bizet’s Carmen, and a solo from Brahms’ First Symphony. The recordings were completed in an anechoic chamber allowing the purest sounds to be recorded.
     The recordings were listened to by 15 other professional flutists. Listening Test A included an excerpt from Carmen played first by player 1 on all flutes and then by player 2 on all flutes. The listeners were asked to guess which flute was being played. Widholm’s results showed that no instrument was identified correctly.
     Listening Test B consisted of the same instrument being played by all seven players. The listeners were asked to describe the color of the sound and again guess what flute was being played. Widholm notes that only one flute was identified correctly, the all silver flute. The 9kt gold flute was usually identified as silver, and the 14kt gold as platinum.
     Widholm analyzed the sound differences heard between players and instruments and found only very slight differences in sound levels between materials. The difference of the instrument with the smallest dynamic range, 14kt gold, and largest dynamic range, platinum, is only 1.5 dB, hardly a gap in the grand scheme. This is interesting because platinum is described as having a strong, powerful, and cutting sound. Widholm found that the dynamic range is greater between players than between instruments.
     He also found that the envelope, the shape the initial tone creates, hardly changes between instruments. He  indicates it is only a measurable difference, not a noticeable one – “the largest difference in sound caused by material over the entire frequenc [sic] range of 0-16 kHz is less than 0.5 dB.”
     Along with Coltman and White, Widholm also concludes that the greater difference in sound production is between performers. Any difference between flutes of different materials is so slight that the human ear cannot hear the differences. 
     While there are two distinct positions to this heavily debated question, some flutists take a position somewhere in the middle. They believe that the sound is better with the more precious and expensive metals because of the greater care and skill the craftsman takes when shaping the flute. Others think that both the metal and the player are integral parts of the overall flute sound.
     Musicians have discussed and argued over this matter for centuries. Even in today’s modern society with high technologies, science does not necessarily outweigh personal opinion and preference. The experience of playing and listening to music is a subjective one, different for each person. There may never be a conclusive answer accepted by all to this age-old debate.

Footnotes
1 Rockstro, R.S. (1928). A treatise on the construction the history and the practice of the flute including a sketch of the elements of acoustics and critical notices of sixty celebrated flute-players (2nd ed.). London: Musica Rara.
2 Toff, Nancy. (1996). The flute book. New York: Oxford University Press.
3 White, J.L. (1980). A spectral analysis of the tones of five flutes constructed of different materials. Unpublished doctoral dissertation, University of North Carolina, Greensboro.
4 Griffiths, P. (1982). BBC radio interview with Marcel Moyse. Recorded in London.
5 Davis, H. (2007). Most expensive flute. Retrieved from http://most-expensive.net/flute on November 30, 2008.
6 White, ibid.
7 Culver, C. (1956). Musical acoustics (4th ed.). New York: McGraw-Hill.
8 Fletcher, R.H., & Rossing, T.D. (1991). The physics of musical instruments. New York:     Springer-Verlag.
9  Culver, ibid.
10 Coltman, J.W. (1970). Effect of material on flute tone quality. The Journal of the Acoustical Society of America, 49 (2), 520-523.
11 Coltman, ibid.
12 Coltman, ibid.
13 White, J.L. (1980).
14 Widholm, G. (2001). Silver, gold, platinum – and the sound of the flute [Electronic version].     Retrieved from http://iwk.mdw.ac.at/Forschung/english/linortner/linortner_e.htm on     October 15, 2008.

References
Galway, James (2003). Flute Material. Retrieved from http://www.thegalwaynetwork.com/notes/material.htm on November 30, 2008.
J.L. Smith & Company. (2008). Materials used in flute production. Retrieved from http://www.flutesmith.com/flute-materials.asp on November 28, 2008.