This article is based on data from the diploma thesis of Renate Linortner, and the paper is available in its entirety for download in PDF (Acrobat Reader) format. The following shorter version is concerned with dynamic and timbre differences only. The complete PDF version (only in german) contains further data on alloys and material analysis of metals used in existing flutes.
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 € 3,000.- and € 73,000.- (!). Double blind tests and statistical analysis showed players‘ and listeners´stereotyped 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.
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. Therefor 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. Coltmans´ experiment: the flutes where built especially for this experiment and without any keywork.
Fig. 1: The test instruments
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 (Fig.1).
A silver coated, full silver, 9 carat gold, 14 carat gold, 24 carat gold, platinum coated and all-platinum flute was played by 7 professional flutists (members of Viennese orchestras including the Vienna Philharmonic orchestra) in an anechoic chamber. The recorded sound material: a chromatic scale over 3 octaves (c4-c7) instruction: convenient forte, a crescendo up to fff and a decrescendo up to ppp on the single notes a4, f5, d6 and bb6, the famous solo from Carmen (Bizet) and the solo of the 1st Symphony of J. Brahms.
Fig. 2: Bizet, Carmen W. Schulz playing on the platinum-flute
Fig. 3: Brahms, Symphony No. 1 R. Linortner playing the platinum-flute
The sound material was analyzed and prepared for a listening test with 15 experienced professional flute players including the seven test players. An additional opinion survey was done on the question of the influence of the material on the sound, response and if there is any relationship between the wall material and the soundcolor of a flute with 111 persons.
A good estimation of the influence of the player and the material on the radiated sound gives an RMS of the played chromatic scale. Differences are rather seen between the players whilst those between the instruments are extremely small. This implies that flute players can realise their subjective imagination of “a good sounding” to a far extent independently of the instrument.
Fig. 4: Soundlevel of the played chromatic scale (seven players with seven flutes)
A common stereotype is that full Platinum flutes provide the the player with a larger dynamic range.
Figure 5 shows the mean value of all players and four notes of the low, middle and high register for each instrument. The difference of the instrument with the smallest dynamic range (14 carat gold flute = 14.57 dB) and that with the largest range (platinum flute = 16.14 dB) is only 1.5 dB! The possibility that this difference becomes zero with an increased number of test players can not be excluded.
Fig. 5: Dynamic range of each instrument (four notes, seven players)
Quite different is the situation if one looks at the individual dynamic range of the players. The obtained dynamic range is between 7 dB and 19.6 dB. The figure shows the mean values for each player, all instruments and the notes a4, f5, d6 and bb6. The highest obtained dynamic is four times as much as the lowest.
Fig. 6: Individual dynamic range of each player (four notes played with all flutes)
As the Dynamic range is a “relative” value, the table below gives information on the obtained absolute values for each note.
|a4||69-80 dB||82-92 dB|
|f5||66-83 dB||81-96 dB|
|d6||72-86 dB||88-100 dB|
|bb6||72-95 dB||85-107 dB|
Tab.1: Absolute dynamic values for each note: mean values of seven players
Similar is the situation for the sound color. The sound spectrum differs extremely between the various players. But analyzing the sound spectra of the notes played by one player with different instruments, only just measurable but not recognizeable differences can be found. This fact was demonstrated strikingly by the listening tests.
Figure 7 points out that the largest difference in sound caused by the material over the entire frequenc range of 0-16 kHz is less than 0.5 dB! The figure shows 7 lines (one line for each instrument). Each line represents the smoothed envelope (cepstrum with 36 coefficients) of the sound spectrum obtained from all players with one instrument. In this way, the influence of the individual player is eliminated.
Fig. 7: Mean spectrum for the seven flutes
The sound examples below give an idea about the influence of the material. One player plays a note with all flutes. The sequence is: silver coated, full silver, 9 carat, 14 carat, 24 carat gold, platinum coated and all platinum.
|sound example 1||player 1, note e1 flat on all flutes|
|sound example 2||player 2, note g2 on all flutes|
|sound example 3||player 1, note g3|
The mean spectra for each player show the opposite situation (differences up to 7 dB, Fig. 8).
|sound example 4||seven players on one instrument|
Fig. 8: Sound differences, mean spectrum for seven players on one instrument
There were two tests made: in TEST A, the Carmen solo and the Brahms solo was presented (from a CD), at first from Player 1 with all instruments, then Player 2 with all instruments and so on. The test persons had to guess the instrument. The result was interesting: no instrument was identified correctly. The best value was that for the 24 k Gold flute: only 22% of the test persons identified it as a 24 k Gold flute. Whereas the wrong allocations had much higher values: 34% identified the Platinum flute as a 9 k Gold flute (only 6.8% identified it correctly) and 32% thought that the 14 k Gold flute is the Platinum flute (11.3% were right)!
silver coated flute
ful silver flute
9 carat gold flute
14 carat gold flute
24 carat gold flute
platinum coated flute
With TEST B, we tried another approach: the test persons listened to one instrument played by all players. They had to describe the sound color and to guess the instrument/material. Then the next instrument played by all players was presented, and so on. Only one instrument (the all-silver flute) was identified correctly, with all other instruments the confusion was perfect! For instance: the 9 k gold flute was mainly misinterpreted as an all-silver instrument, the 14 k gold flute was identified as the platinum instrument and the silver coated instrument was assigned to all instruments (with each instrument at least one test person thought that it is the silver-coated instrument).
The descriptions of the soundcolor for each instrument were separated into 5 categories:
As expected, the most significant assigned expressions for all instruments were the “contradictionary expressions”: for example, the sound color of each instrument was evaluated as “bright” and simultaneously as “dark” or “full/round” and “thin/sharp”.
The evaluation of the sound quality showed a very small range: the values for all instruments can be found between 2.16 and 2.92. In addition to the evaluation of the sound quality, the test persons were free to use a “+” for “I like it” and a “–” for “I don’t like it”. The following table points out the listeners’ preference depending on the played music.
|instrument||sound quality (averaged)||Brahms||Bizet|
|9 carat gold||2,16||+ + + +||+ + + + + + –|
|24 carat gold||2,38||+ + + – –||+ + + – – – –|
|Platinum||2,60||+ – – – –||+ + + + – – –|
|silver coated||2,66||+ + + + + – –||+ + + + + – – – –|
|platinum coated||2,79||+ + + –||+ + – –|
|14 carat gold||2,79||+ + + – – –||+ +|
|full silver||2,92||+ – –||+ + – – – –|
Tab. 2: Subjective appraisal of the sound quality of the test instruments
Tests with experienced professional flutists and listeners and one model of a flute made by Muramatsu from 7 different materials showed no evidence that the wall material has any appreciable effect on the sound color or dynamic range of the instrument. The common stereotypes used by flutists and flute makers are exposed as “stereotypes”.