yes, i am aware changeable joints have been done. my ideas are not so ingenious as that. in fact, they are far less practical, but much more fun.Thomas-Hastay wrote:Many new flute designers are intimidated by the Acoustic Mathematics needed to make a flute and tone hole set accurate. I can say from experience that it is easier than you think. Basic Geometry and Algebra using a standard scientific calculator is all that is neccessary.
Conical bores and joints are used in woodwinds to manipulate the Nodes (places of least vibration) and Anti-Nodes/Waves (places of greatest vibration). By changing the angle or taper of the bore a designer can "tune" these Nodes and Waves for matching harmonics. Why? As each overblown register is acquired, the flute extends the air column a little at the toneholes,voicing and bore end due to increased input velocity. This "Phase-Shift-Flattening-Effect" is common to most woodwinds.
Recorders use a combination of tapered conical bore and a "speaker/thumb-hole" to tune the registers and the common "concert flute" uses a tapered headjoint and a tunable "plug" to balance the Nodes and Waves for inter-register tuning. A conoidal bore has a drawback though, reduced range. Any Tin Whistler will tell you that their Generation cylindrical bore will play more than 4 registers with very little embouchure correction, but Recorder players are restricted to a strained 2 1/2 registers.
Materials do contribute to hamonic acoustics, but in a minor way. Sound travels faster in harder materials and this favors high harmonics. The opposite is true of softer materials, like wood, that dampens high frequencies to favor low harmonics. It is the Harmonic "Tone-Color" that is effected by types of materials. (The speed of sound in materials are calculated using the "Young's Modulus" fomula.)
http://en.wikipedia.org/wiki/Young's_modulus
Changeable Joints: Thes are not "new" to woodwinds. Renaissance and Baroque instruments have been made with sets of joints for changing keys. This is done in many ways, including tapered joints, reduced/enlarged "stepped" joints and tapered foot joints. These techniques are generalized as "Bore Perturbation".
Once you get past the "stigma" of Acoustic Mathematics, you will achieve epiphany after epiphany! Simple calculator math for designing woodwinds can be found at...
http://www.shakuhachi.com/TOC-CM.html
I recommend the books of Bart Hopkin and Lew Paxton Price. Give it a try! I bet you're smarter than you think!
and thanks for all the links!
