... in which the writer demonstrates his ignorance

[Steve Bliven]

I got into a conversation the other day and, part-way through, I realized I had no idea what I was talking about. The discussion was over where the sound comes out of a flute. Among those present, opinions varied over whether it was from the embouchure, the lowest tone hole, the (open) end of the flute, or all of the above. Could someone more technically oriented clarify this for me?

Thanks and best wishes.

Steve

[Tunborough]

[... in which the responder trots out their own little bit of alleged knowledge ...]

I have seen one bit of research, on fipple flutes as I recall, that found about half the sound came from the window and half from the lower part of the flute. If there are open toneholes, they would share the load: much of it would come out of the top open tonehole, but those lower down and the end of the flute would also participate. I imagine the same would be true of transverse flutes.

[Wanderer]

My understanding (which, admittedly, could be flawed):
The sound in a flute is caused by the air vibrating at the embouchure hole. As you blow across the edge of the embouchure, a pressure wave is set up inside the flute body which causes air to alternately go into and out of the flute. This alternating action causes a vibration, making the tone. The speed of this vibration is caused by the resonance of the wave, which is determined by the tube length and determines the pitch. Opening tone holes shortens the tube length, changing the resonance of the pressure wave, changing the pitch.

Since the flute body mostly serves mostly as an air pressure regulator, and the sounds are caused by vibration at the embouchure, I would imagine that the majority of sound comes from the far edge of the embouchure hole (where the air is getting split). Of course, being a vibration, sound probably propagates and there may be some measurable amount from other areas of the flute, but I imagine it's negligible by comparison.

Some links for further reading:
https://www.yamaha.com/en/musical_instr ... sm002.html
https://newt.phys.unsw.edu.au/jw/fluteacoustics.html

[jim stone]

Second this.

[Geoffrey Ellis]

It comes out pretty much everywhere I think Having said that, the embouchure hole is primary. I say this based upon making recordings of the flute in my studio and the microphone tells the story. Also, watch any flute player on stage in front of a mic and notice where the mic is relative to the flute. No one is miking the bottom of the flute, for example.

In studio settings, the best results I had came from pointing the mic in the general direction of the embouchure hole, but far enough back to also include the finger holes. In a live setting, you want the mic in close so you don't pic up other instruments and room noise, so you close-mic it at the place that counts the most: the embouchure. I know of one recording engineer at a pro studio who favored a ribbon mic up at the ceiling above the flute player! This ensured that he captured all of the nuances of the flute, including how it sounded in the room itself. Very interesting but not practical in a live setting.

[Tunborough]

sound probably propagates and there may be some measurable amount from other areas of the flute, but I imagine it's negligible by comparison.

Pointing the tail end of a flute or whistle at a sound level meter while playing the bell note demonstrates that there's quite a bit of sound coming out that end.

[Geoffrey Ellis]

sound probably propagates and there may be some measurable amount from other areas of the flute, but I imagine it's negligible by comparison.

Pointing the tail end of a flute or whistle at a sound level meter while playing the bell note demonstrates that there's quite a bit of sound coming out that end.

On a few occasions I've placed a dynamic mic pointing up into the foot of the flute while I play. You definitely will get sound waves coming out of there, but if I remember correctly it was biased toward lower frequencies (gave a "bass-y" sound).

[PB+J]

Flutes are weird!

[adamstjohn]

I agree that, when playing into a mic, a lot of sound comes from the embouchure hole. However there is somw conflict of interest here: the embouchure hole stays stationary while playing-- and thus is easier to mic-- while whatever is 'the open tone hole' or 'open end' shifts around as you play-- and thus is difficult to mic.

I dont know the physics thaat well, but heres some food for thought: flutes are mostly not resonating bodies (like a guitar or fiddle or drum). Rather it is almost entirely the air space itself that acts as a resonator. Very very very little sound is emanated from the exterior wall of the flute (fact from Nederveen).

Secondly, at the edge of the embouchure the air stream is oscillating back and forth, over and under the edge. As far as I understand, this is based mostly on a balance between the inside and outside of the flute. Thus I would guess that about half of the sound emanates from the embouchure, while approximately the other half is either emanating from the open end, or radiating from the pads of closed holes, or being lost to friction and heat with the wall and turbulences and moisture etc.

Then again, the players mouth and throat and sinuses are part of the system, so maybe most of it is resonating from their eyeballs! Who knows!

[Juan Pablo Plata]

Blow into a bottle and will have the answer.

[RudallRose]

everything you'll ever need to know about it right here.
Essentially the same on a simple-system wood flute
https://newt.phys.unsw.edu.au/jw/fluteacoustics.html

[benhall.1]

everything you'll ever need to know about it right here.
Essentially the same on a simple-system wood flute
https://newt.phys.unsw.edu.au/jw/fluteacoustics.html

That's a great article, that I've looked at every now and then over the last few years. I've just looked at it again. I can't see the answer to the poster's question. Maybe I just can't see it for looking ...

[benhall.1]

I got into a conversation the other day and, part-way through, I realized I had no idea what I was talking about. The discussion was over where the sound comes out of a flute. Among those present, opinions varied over whether it was from the embouchure, the lowest tone hole, the (open) end of the flute, or all of the above. Could someone more technically oriented clarify this for me?

Thanks and best wishes.

Steve

Whenever you go and see a great flute player in concert, the mike is directed straight at the embouchure hole. Typically, there are no mikes directed anywhere else. I think that says something.

[PB+J]

I looked at the "gearslutz" forum, which is run by and for audio engineers, and the consensus seemed to be that most of the action was at the embouchure hole, but that you needed to get some of the sound escaping from the finger holes or it wasn't going to sound right. The general recommendation was micing a feet feet back from the flute. Same with the sax--the general view was don't mic the bell only, because the soundholes are important. That's obviously not going to work live. Sax players Ive worked with have used a clip on mic at the bell. Flute players just stand near a vocal mic.

[Steve Bliven]

everything you'll ever need to know about it right here.
Essentially the same on a simple-system wood flute
https://newt.phys.unsw.edu.au/jw/fluteacoustics.html

That's a great article, that I've looked at every now and then over the last few years. I've just looked at it again. I can't see the answer to the poster's question. Maybe I just can't see it for looking ...

The OP continues to be confused by this topic—but feels better as it seems that confusion is broader than just in his mind. The closest that the article from RudallRose seems to come is in the summary in the intro:

Once the air in the flute is vibrating, some of the energy is radiated as sound out of the end and any open holes.

This seems to suggest that the sound comes out, to one degree or another, from any open hole,l but I can't tell if it is assuming that the bulk of the sound comes from the embouchure hole. Other comments seem to suggest that the nature of the sound varies depending on the source of the sound leak. Maybe the OP should just shut up and blow...

Best wishes.

OP Steve