As a physicist and instrument designer for over 50 years, I can tell you that:
(1) All acustical aspects of flutes and other instruments have been known for over 100 years and can be completely perdicted mathmatically and verified experimentally.
(2) The sound of all woodwinds are completely dipendent on the reed, the coupling of the reed, and the geometry of the instrument. In case of flutes, the material has not influance what so ever on the sound, just the geometrical aspects of the holes, cheminies, tube measurements. Even differences of .001 inches effect the sound and harmonic content.
(3) To dramatise this, sometimes physicist have two identical flutes made of cement, wood, silver, and ground glass. Players and listeners cannot tell the difference.
(4) The fact that good flute players insist that the material of construction of a flute makes a difference, would make a good study in distortion in thinking.
(5) It is true that typically a box wood flute will sound more like another box wood flute than a blackwood flute. But the reasons are shrinkage patterns and not the acustical properties of the material.
(6) If anyone is interested in the scientific (or lay) literature on this subject, inquire with me at .