Flute Makers: What Affects Tuning And How?

[brokish]

Hi all,
It seems to me there are lots of variables that affect the tuning of a flute. For example:
• Finger hole size (and shape?)
• Finger hole position
• Cork position
• Wall thickness
• Bore taper
• More that I’m sure I’m missing

I imagine it’s pretty easy to create a flute with the first octave in tune, but when you want the second octave to be in tune as well (or a particular cross-fingering such as OXXOOO), then that’s where the various “levers” need to be tweaked to keep that first octave in tune while altering the resulting tuning of second octave notes (and desired cross-fingering).

I’d love to hear everyone’s thoughts on how the parameters listed above (or others) affect tuning. For example, if wall thickness impacts tuning, could you undercut a particular finger hole, and what would the effect be? What is the effect of larger holes moved further down the flute? How does bore taper come into play—does it change the tuning between low E and high E more or less than the tuning between low B and high B? Etc.

I’m looking forward to your thoughts and pointers to other threads or references.
Kevin

[skyspirit]

Hi all,
It seems to me there are lots of variables that affect the tuning of a flute. For example:
• Finger hole size (and shape?)
• Finger hole position
• Cork position
• Wall thickness
• Bore taper
• More that I’m sure I’m missing

I imagine it’s pretty easy to create a flute with the first octave in tune, but when you want the second octave to be in tune as well (or a particular cross-fingering such as OXXOOO), then that’s where the various “levers” need to be tweaked to keep that first octave in tune while altering the resulting tuning of second octave notes (and desired cross-fingering).

I’d love to hear everyone’s thoughts on how the parameters listed above (or others) affect tuning. For example, if wall thickness impacts tuning, could you undercut a particular finger hole, and what would the effect be? What is the effect of larger holes moved further down the flute? How does bore taper come into play—does it change the tuning between low E and high E more or less than the tuning between low B and high B? Etc.

I’m looking forward to your thoughts and pointers to other threads or references.
Kevin

me too Kevin

[pipersgrip]

Yea, all that: undercutting, hole placement, beveling the holes, the length of the headjoint or body, cork position, embouchure position. It has a lot to do with the combinations too. A lot has to do with your lips and blowing as well. I am a sharp blower, so in tune for me, might not be for you. That is the one tricky thing about flute tuning. There is a lot more to it, but I am not a true expert when it comes down to the whole design.

[Casey Burns]

You can probably find lots of answers reading Benade's "Fundamentals of Music Acoustics". Describes how instruments work.

Simple principles: bigger the hole, the sharper. Undercutting affects 2nd octave more than the 1st. More undercutting, the sharper the 2nd octave. Wall thickness affects tone more than tuning. Bore - a very complex subject - suffice it to say there are flute bores that work and ones that don't. Otherwise its no simple answer - one learns this stuff by making them. After 30 years I am still learning.

Casey

[skyspirit]

You can probably find lots of answers reading Benade's "Fundamentals of Music Acoustics". Describes how instruments work.

Simple principles: bigger the hole, the sharper. Undercutting affects 2nd octave more than the 1st. More undercutting, the sharper the 2nd octave. Wall thickness affects tone more than tuning. Bore - a very complex subject - suffice it to say there are flute bores that work and ones that don't. Otherwise its no simple answer - one learns this stuff by making them. After 30 years I am still learning.

Casey

In my humble opinion, this is right on the money. Especially, "one learns this stuff by making them". A Native American flutemaker told me that you have to remember what you did and be consistent. I think that he is wise.

[Tunborough]

You can probably find lots of answers reading Benade's "Fundamentals of Music Acoustics".

I'll second Casey's recommendation, and also add Neville Fletcher and Thomas Rossing, The Physics of Musical Instruments.

But it still looks to me that nobody really understands exactly what's happening at the embouchure hole of a flute, or the window of a whistle.

[Casey Burns]

Google "air reed" and you will find lots of explanation of how a flute embouchure works. Oscillation. When you blow over the tone hole, the Venturi effect deflects this air stream down into the hole due to pressure differences. Then that collapses and the air is blowing across the hole. This repeats and its rate of repetition (frequency) is controlled by the acoustical length of the tube, which is controlled by fingerholes that effectively cut off the tube at different places.

Also, the tube is bent back on itself at the plug. This is a compromise necessary due to the basic Vertebrate pattern of Humans. We evolved with only one arm on each side of our bodies. Had we had two, then you would see both a left handed and a right handed set of tone holes with the embouchure in the middle. The plug instead saves us from this by acting as a reflector so that one side does all the work.

In that 4 armed scenario, it could get confusing since each side of flute would have to be played exactly as the other. So fingering F# on the right side would look like XXX X00 but it would also have to look like 00X XXX on the left side. The upper left arm would play the upper right flute fingerholes while the lower left arm would have to play the upper left flute fingerholes in opposite symmetry, with perfect timing. And the other hands would do the same but opposite. It could get very confusing. One would have to Patent the tone hole system. My head is now hurting from thinking how this would work out.

The amount of wood or plastic required would double.

Casey

[eilam]

kevin, there is a great book by Adrian brown (pretty sure thats his name).....it's mostly about tuning recorders, but will totally apply to flute........it's very interesting and much more complex then you think.
if you can't find it.....i'll look for it here.

[hans]

It has been newly reprinted:
http://www.dolce-edition.com/workshop.html

[eilam]

it's the best book that i have found that deals with tuning.

[Thomas-Hastay]

There are some basic rules to flute acoustics that are not "rocket science". Here are some of the most common general rules.

Basic Length/Bore Ratio: Bore ratios of between 1/26 and 1/32 are common. 1/26 will favor high harmonics (flutey) while 1/32 will favor the lower harmonics (reedy). Restrictive bore diameters attenuate weak high frequencies. Spacing of approx. 10 times the bore diameter between the top tonehole center and the Embouchure center.

Embouchure Depth: Flutes with less than 1/8th inch depth will suffer from poor resonation and bad response time. Flute plates increase response times due to surface tension removing most of the turbulence near the voicing.

Conical Flute Taper: The angle of the taper controls the tuning of the 2nd and 3rd register to the fundamental register. This is most often seen in Recorder Taper. The Drawback? sharp tapered instruments are restricted to a scale range of only 2+ octaves. Tinwhistles use "pitch bending" to correct flatness in the upper registers and allow greater scale range of 3+ octaves. Flutes use the small cavity above the Embouchure to tune the Harmonic Scale (critical to register tuning) and a "Boehm Taper" in the headjoint works the same here as the conical bore works for the Recorder inter-register tuning. Note: Spacing between the plug face and the embouchure center should be 7 times the internal diameter divided by 6. Adjustment in/out favors upper/lower register dominance.

Undercut Toneholes: When a player shifts to the upper registers there is a slight shift in the "perfect" placement of the toneholes (anti-node phase shift) caused by greater velocity of the aircolumn. Undercutting allows the air to "follow" the upcurve (surface tension) at the tonehole and not "bypass" the tonehole (weak tone)

Deep Toneholes: Increased internal pressure in the upper registers cause the aircolumn to "push up" into these toneholes and increase the total cubic volume of the bore leading to flat pitch. Embouchure correction is possible but problematic. Each increase in register componds this flatness.

Tonehole Size/Pacement: Each tonehole has a variable "window" for placement (between anti-node bounderies). Lower down the bore/Larger hole-Higher up the bore/smaller hole. Large hole/Louder sound-Small hole/quiet sound.

There are many more, but this post is overlong now. I suggest the Books of Lew Paxton Price, designed with the rank amateur in mind. ("Secrets of the Flute"rev. is best to start) Please jump in and add to my small list. I'm sure there are others who wish to share(?)