Flute/Audio Geek Question

So, looking through spectral analysis of my different flutes, I notice a strange dip around 10K on my alto flute. It’s as if someone ran a notch filter right at that frequency. (It’s an alto with a straight headjoint, not a curved one.) Here are the examples. They are raw, not processed, all recorded on the same microphone and digital recorder.

This shows an example of my alto flute playing in a small room. It looks like a notch filter around 10K:

The next shows the same the alto flute, same music, same equipment, in a different room. The same dip around 10K and here the bulge just under it is more visible. (This one has the view up to 20K.)

For comparison, here is an example of my bass flute playing, same equipment, same room as the previous example:

And for another comparison, here is my C flute sound, same equipment, same room as the previous 2 examples:

Does anybody know what is going on? Any alto flute makers of headjoints know if this is something typical? Any alto flute players want to compare?

[Edit: I received an answer on Facebook from Dave Gedosh suggesting that it has to do with the construction of the flute. Then I received an email from a reliable source that gave this explanation:

I have a theory that the notch you see may be due to the natural resonance of the flute type you are playing due to diameter of the flute.

Not knowing room temp nor altitude I predicted various notches for various flutes in a linear fashion based on your observed notch .

Alto flute length 34”, 1” diameter, wavelength 13khz @ 20 deg c, sea level Seen at At 10 kHz

C flute length 26 1/2” ,3/4” diameter 18khz @ 20 deg c , sea level Predict 14 kHz

To check this, I take the same C flute example as above, but shown up to 20K and with one channel zoomed in. There are dips around 12K and 9K. Maybe because of the B foot? Cologne is about 37 Meters above sea level, and it was about 20°C.

Bass flute length 52” ,1 3/4” diameter 7.72 kHz Predict 6 kHz  Note bass flute notch is lower (allowing a lower range ? 🙂 ) {edit: is the curvature of the headjoint taken into account here?}

Maybe I am wrong but the coincidence of the wavelength and the flute diameter seems too much to ignore.]


More on Circular Breathing

On April 8th this year, I will be in Krakow giving a workshop on circular breathing and performing Robert Dick’s legendary Flames must not encircle sides. About seven years ago I made the tutorial video below, but have been considering a re-make of late. More for clarity, rather than content. And I have learned a few things along the way since then.

Just quickly, here are a few.

Some players feel more comfortable starting on the head-joint. I didn’t do this myself, but can understand why.

Another thing that helps is to embrace the bump that happens while expelling the air and re-taking the breath. Ride it, even. It is normal to experience it and will get better with time, if you persist. So many flutists give up when they hear the horrible gap for the first time.

Note to self: write a practice guide to Flames must not encircle sides. This piece is so cool!

Here is the circular breathing tutorial, if you haven’t seen it already:


Glissandi and Quarter Tones on the Lowest Notes

I often get asked if glissandi and quarter tones are possible on the lowest notes of the flute. Sure, I say, theoretically. Nine times out of ten, I regret this positive answer. Here are the notes in question:

The lowest notes on the flute

On these notes, glissandi and quarter tones are produced with the embouchure. There are no open holes to help. This is also true for Kingma system flutes, although they can easily start quarter tones from D. Since the tube is long (especially if the flute in question is alto or bass), don’t expect large-interval glissandi.

Lipped glissandi that follow the easy (but not hard-and-fast) rule work well:

  • Glissando upwards with crescendo
  • Glissando downwards with decrescendo

Since quarter tones must also be produced with the embouchure, there are limitations of speed and accuracy. And the bigger the flute, the the longer the tube and the less pitch flexibility you have.

Bear in mind that notes that are lipped down will have a diffuse character that will not carry well in an ensemble situation. Notes that are lipped up will carry easier, but may have a higher air component.

These are just caveats, not prohibitions. It’s always good to ask your local flutist for advice 🙂