Sorry for the pun, and also apologies if this topic has been aired previously, but as a relative newcomer to the world of piping, I find it intriguing, and not a little confusing, on the subject dear to every pipers heart…THE REED !
Having read numerous articles on UP’s and other bagpipes, one distinction usually mentioned between the Great Highland Bagpipe and the Uilleann Pipe, is the former is mouth blown whereas the latter is bellows blown.
This, we are told, limits the GHP to one octave plus one note, since the reed must be robust enough, (ie short and fat), to withstand the high moisture content of the air being blown through it.
The UP reed, being bellows blown, can be made longer and thinner, enabling it to manage two octaves.
So far so good…however, what about other members of the woodwind family ? The Saxophone, Clarinet, and most notably, the Oboe.
These instruments are played with the reed actually in the mouth of the player, and the oboe reed (which is not that dissimilar to a UP reed) covers almost three octaves !
On the flip side, the Northumbrian pipes are bellows blown but limited to one octave.
Confusing isn’t it ?
As my old English teacher used to say…please discuss.
No reed expert by a long shot … But with the direct mouth-blown single and double reeds you mention, you control the reed closure and tension with the lips, applying more lip pressure as you ascend. Something that is obviously not possible with any capped reed.
Regarding Northumbrian pipes - the bore is cylindrical, rather than conical, so the overblown notes, if produceable at all, would not be one octave higher but one octave and a fifth higher; thus keys would be required in any case.
Many if not all of the mouth blown orchestral instruments have an octave key which assists in getting the second octave (octave and fifth in the case of the clarinet). This key is effectively a controlled leak creating a node point and change the sound waves in the bore (as I understand it).
The Northumbrian pipes have a range of an octave and a fifth to two octaves but rely on keys to extend the range above and below the fingered notes. They can be made to overblow thought this is not something within the tradition. There is also evidence that some highland pipers in the past could overblow / pinch up to a high b above the current top high A. I amn able to do this on my highland pipes but again it is not a common thing.
It’s not a matter of the octaves being in tune or out of tune. It’s the acoustical physics of a closed-end cylindrical bore pipe. In effect, only the odd-numbered harmonics (1, 3, 5, 7, etc.) are resonant within the pipe. So overblowing results in a jump to the 3rd harmonic - which, in the harmonic series, is 1 octave + 1 fifth above the fundamental. The clarinet is probably the best-known example, with the throat register keys accounting for the extended fundamental range.
Both open-end cylindrical pipes (like flute) and closed-end conical pipes (like oboe) resonate the complete harmonic series (1, 2, 3, etc.). So they overblow from the fundamental to the 2nd harmonic, which is the octave.
limits the GHP to one octave plus one note, since the reed must be robust enough, (ie short and fat), to withstand the high moisture content of the air being blown through it
Not true - Bassoon and Oboe reeds are not as feindishly hard to blow as GHB’s - sort of macho Scottish thing I guess. I have ben told that this may be a recent thing as there are tune books in existance showing that the GHB could and was played well into the second octave.