2 – Understanding your flute


So – this cut-away diagram is from the side of the “business end” of your flute… click it for a bigger version. The flute is made by joining two pieces of wood together after shaping them on the inside; that’s where the “join” on the drawing is. Figure 1 shows a static flute which is not being blown.

The flute works (makes a sound) by focussing a laminar flow (all the same speed, all going in the same direction) of air onto a cutting edge. This splits the airflow; some of it goes out into the wide blue yonder and is lost – and some goes into the bore (resonant chamber) (Figure 2). This starts to push air into the bore. Now – you’d think it would just come out the end, right? Thing is, air has a mass – which means it likes to stay where it is – it resists movement. As you get closer to the “south” end of the flute, the resistance increases because you’re trying to move a greater mass of air. So – the bore starts to fill up (we haven’t stopped blowing). At some point, it is “full” – i.e. the weight of air in the bore is too much for the incoming air to push in any more. So – now, the split goes OUT into the wide world, ONLY (Figure 3). This creates a small vacuum at the back of the cutting edge; which draws air out from the bore. The bore empties… (Figure 4) which creates a vacuum inside the bore and starts to draw air back in… (Figure 5) and again the air starts filling up the bore.

If the flute is tuned to “A” above “Middle C”, this cycle happens 440 times per second! Less often for lower notes, and more often for higher notes. Most of the sound therefore comes from the gap behind the cutting edge: the “True Sound Hole”.2015-05-10 12.38.53

When you open playing holes on the flute, you’re effectively allowing some of the air to move out of the flute more easily, closer to the true sound hole; that makes the cycle happen more quickly, which plays a higher note.

The unique feature of a Native American design is the bit BEHIND the true sound hole; the Slow Air Chamber, Ramp and Flue. The slow air chamber takes the airflow from the player, which is pretty turbulent and uncontrolled, and slows it down – damping out variations and “wobbles” in flow. Then, the air goes up the ramp, and is compressed and slowed further. The flue ensures all the air is going the same way at the same speed – and then as the air exits the flue, into the true sound hole, the “Venturi Effect” speeds the air up to be split by the cutting edge. This arrangement combines to give the Native American Flute its unique, haunting sound.

The Scale

Nowadays, musical taste is largely driven by the European method of writing music, which has eight major notes and five semi-tones in between: A, B flat, B, C, C Sharp, D, E Flat, E, F, F Sharp, G, and finally A Flat. When played together (for instance on a piano) you can make “Chords”. For instance, C, E and G played together make “C 2015-05-10 13.02.27Major”. C, E Flat and G make “C Minor”. It’s widely agreed that major chords sound happy and up-beat; whereas minor chords sound sad and mournful.

My Native American style flutes have six holes, and with the “basic” fingering scheme can play only 6 notes. If the flute is in “A”, it can play A, C, D, E, G and A… which means it makes a MINOR chord (A, C and E together is “A Minor”). As the top note is the same as the bottom, just one octave higher, that leaves five main notes. The flute is said to be tuned in a “Minor, Pentatonic” scale. There is “Cross Fingering” available to produce the notes “missing” from the basic fingering.

That is not by any means the only way to tune them; they can also be tuned in a “Diatonic” scale which makes a Major chord, and they can also be tuned to match the traditional flutes of the ancient Native Americans – although there is much debate about how those were tuned since there is very little real information out there. There are a number of “Grandfather Tuning” methods in circulation which are often based on the dimensions of the intended player’s body.

This series will focus on the Minor, Pentatonic scale, which is so popular among players.

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4 Responses to “2 – Understanding your flute”

  1. Nathan 23/07/2015 at 07:45 Permalink

    Question – based on the diagram above, I wonder – what is the degree of the bottom of the cutting edge you’re making? On the diagram above it looks almost like 30 degrees. Personally, I go for 45 degrees angle. 30 degrees used to give me a hell of a sharp sound. 45 degrees angle seems to make the flute sound a bit softer. Have you ever experienced that?

    • Tom Kelsall 23/07/2015 at 10:04 Permalink

      To be honest it’s not something I have ever experimented with; I will try it and let you know! It would be fantastic to choose the sound I get to that level of accuracy.

      • Nathan 23/07/2015 at 17:15 Permalink

        I can’t remember exactly where, it may have been Flutopedia, but I’ve read once that woodland flutes used to have a more blunt cutting edge to make the sound softer, warmer and a bit more airy; while the plains people prefered more sharpt instruments, with very sharp splitting edge. I tried this in my own flutes and obviously, the sound is affected.

        It’s quite logical that the angle of the cutting edge makes a difference, too. For example, Fujaras and many European whistles have a smaller angle of the cutting edge, 30 degrees and sometimes even less, and their sound is often much sharper than what we experience in case of most Native American style flutes.

        So yes, it’s worth experiementing :).

        • Tom Kelsall 23/07/2015 at 21:38 Permalink

          I will – my current one I’m making is about 30°; I shall make the next one 45. I prefer a sharp cutting edge myself but not RAZOR sharp – I do blunt it a little.