Someone has asserted that a flute’s sound emerges at the embouchure hole. This makes sense to me, in fact. But then the question arises: why do bigger tone holes make for more volume, all things being equal?
Good Question Jim. Not that I would have the immediate answer ( or even the right one ), but my first thoughts would be along the lines of wind resistance. I would assume that the larger holed flutes put up less of a barrier to the air escaping through them as the flute is being played than a smaller tone holed counterpart. The net result would in theory allow more air to pass over as well as under the embouchure in a given time - creating more volume, all things being equal. i.e. two identically dimensioned flutes apart from differing tone hole size.
I have played flutes with differing tone hole sizes and have noticed that flutes with larger tone holes have the propensity to be louder. However, in these cases, quite often all things are not equal, as flutes with smaller tone holes often have smaller, more circular embouchures and possibly narrower bores.
A good bit of sound comes from the tone holes too.
And, yes, you need a bigger embouchure to drive a bigger bore and the holes must be sized relative to the bore in order to sound properly.
Tommy
Check out http://newt.phys.unsw.edu.au/jw/fluteacoustics.html
Great reading for any flute nerd.
As I understand it, larger toneholes make the sound of the flute richer in high harmonics. This makes the flute sound “brighter” or “buzzier”. It also makes it sound louder, since our ears are more sensitive to higher frequencies.
The flute sounds because the air column “inside” vibrates, it changes from being more compressed to being less compressed at the frequency of the note being played. Air molecules enter and exit the embouchure hole and the finger holes (top open hole most) because of theses pressure changes, so air goes in and out both at the top and lower down at the finger holes. The sizes (and shape) of embouchure hole and finger hole(s) will restrict this air movement, by offering resistance (as does the bore size). So bigger holes equals less resistance, which means the player can drive the flute harder, meaning more air will go in and out the holes, which results in a louder sound, because more air molecules can excite a stronger vibration of air outside the flute, and it is this we hear.
My observations are that the bore and embouchure are bigger factors in volume production than general tone hole size. A poorly voiced embouchure and a bore that is incorrect will not increase volume on any flute with large holes. Conversely, it is possible to create a loud flute with smaller and closer spaced fingerholes as long as the bore and embouchure are working well together and are efficient. I know this because I make such flutes with these characteristics every day.
Actually it is what the player is hearing. What the audience hears really has more to do with the skill of the player than the flute’s characteristics, all things being equal. Add sound sysems or recording equipment to the mix and you get different results and its unfair to compare merely on hole size when all of these other factors are introduced.
Of course, there is a limit. Only a few bores seems to support a certain layout and size of tone hole. Larger is easier to stumble upon - smaller not so. Much of my flute career has been iteratively discovering and rediscovering what works. As my reamers wear out they start changing the bore characteristics and sometimes I have to search and zero in on what I am seeking for and other times I stumble upon an acoustical pot of gold.
Casey