A Cruise Down the Bore River Part 3
We come now to the final segment of our journey downstream. As in both wing and boot, there is sometimes confusion about both the nomenclature and the function of the tone holes.
- E hole – The first open hole on the long joint. Though the pad cup over this hole is activated by the left thumb on the ‘D’ lever, this first opening is the hole from which E2 emerges. It’s an extension of the bore from the closed pancake key…which is really over the F hole… a bit confusing, eh? Remember how the wing joint C extends through the tenon to the first open hole on the boot? The same principle here for E2; it straddles the larger tenon connection.
- Eb hole – Another 115mm downstream brings us to Eb2 tone hole. It’s worth taking some time to talk about this tone hole and its importance to the third register of the bassoon. Up to this point, we have largely assumed that the nomenclature applies to the principle bore opening for each note. This is as true for Eb2 as F3, or any other hole. As long as we’re using the metaphor of a river, it makes sense to remind you that bassoon pitches emerge from the tendency of any length of bore to establish a standing wave. You’ll find explanations of this here and here.
Standing waves are established when a downstream pressure wave meets a tone hole; some of its energy emerges from the hole to eventually excite our eardrums, but much of its energy is reflected back upstream. When the downstream and upstream pressure waves meet, they start reinforcing or cancelling each other’s energy, creating nodes and antinodes where pressure or displacement are either at maxima or minima. In the Bore River metaphor, these might appear as stationary waves or calm spots. You might assume that the standing wave extends only as far as the first open hole. That’s true for some wave components, but remember that the tone of the bassoon consists of a complex mix of harmonics, so the standing wave is not a simple, tidy entity. While the lower frequency harmonics tend to lose their energy to the first open hole, successively higher harmonics extend further downstream. The long tone holes on the down bore of the bassoon act as frequency filters, separating lower and higher harmonics and allowing some energy to escape and some to continue as standing waves further down the bore. This behaviour explains all the complex cross fingerings that you have come to love! I’m sure you’re delighted…
Most bassoonists read paragraphs like that and simply shrug their shoulders…
But let’s get back to that Eb3 hole. You’ve learned that it plays an important role in tuning and refining many notes: G3, E4, F4, F#4 etc… How is it possible that opening a tone hole so far downstream from these tenor range notes has such an effect? The explanation is this: while the length of bore for the fundamental harmonic is typically from the reed to the first open hole, the effective length of the standing wave becomes longer for the higher spectrum components of the sound. When you play tenor F4 – based on a bore extending to the A tone hole on the boot – higher harmonics of that note are finding their way all the way to the long joint, and are therefore altered by any changes to open or closed holes.
Our Little Bassoonist, watching the motion of water on the river, might see slower and bigger waves reflecting off the shoreline, while the choppy little waves continue far downstream ahead of her.
- D2 hole. Yes, the third opening on the long joint, right under your left thumb. While the pad cup is attached to the C key, the tone hole underneath is where D2 [74hz] lives. Bassoon makers and technicians often make significant alterations to this tone hole as they endeavour to make the D2 lower in pitch. Here is why. By extending the length of the ‘chimney’ we effectively make the bore a bit longer, so the standing wave will extend a bit further. But once we are this far downstream the tone holes are very short, causing a reduction in the filtering of the higher harmonics. Look at how long the tone holes are in the wing and the down bore of the boot. These longer chimneys are essential both for tuning and controlling the higher harmonic components. Low D is indeed a sharp note for certain kinds of reeds. To address this tendency, we often see well executed extensions to make the hole longer. While this approach may help sharper reeds there may also be trade-offs – affecting the tuning and resistance in the 3rd harmonic tenor region, especially F4.
(Note that this tone hole originally had an extended chimney – you can see the inlaid wood. It made a great low D but compromised the tenor resistance.)
- C# hole. This is the fourth opening on the long joint [the last hole on a divided bass joint/bell model]. In addition to its primary role in the establishing the 69hz low C#, it has similarly versatile effects on several higher register notes including G3, D4 and above.
(This photo shows the hole on a divided bass joint.)
- C hole. This is the last hole on a typical long joint, or the first of the two holes on a divided bass joint. [We used to call this a Gentleman’s Cut…] Don’t mistake the name of the mechanism – the left thumb low B pad cup action. The open hole produces low C.
(This photo shows the hole on a divided bass joint, hence the metal band covering the tenon.)
- B hole. It’s been a long journey downstream from the tip of the bocal to this final, and largest, hole. It’s worth noting that while the chimney height of all the bass joint holes are fairly consistent from 19th century Heckel to 2023 manufacturers everywhere, the geometry of these holes has changed a lot. Up until the late 1940s it was common to see a lot of undercutting of these 6 holes. Instead of being simple [but short!] cylindrical holes, they were often enlarged to join the bore with a soft curve. This allowed a bit more higher component energy to emerge, giving a bit more colour to the sound. It also permitted the player to select both higher and lower pitch centers for notes in the bottom range. Straight chimneys tend to help center the pitch with more definition, which is certainly a trade-off for the player. This undercutting occurs most often in the bottom half of the bassoon. The smaller, longer tone holes in the wing and the down bore of the boot rarely exhibit this modification. However, they are often slightly conical in shape, with expanded diameters at the exit of the hole.