Brains and Membranes by Christopher Millard – Chapter 14 – Reed My Lips

Brains and Membranes by Christopher Millard – Chapter 14 – Reed My Lips

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 14 – Reed My Lips

As our Little Bassoonist climbed the ladders into the high register she found herself thinking about the adaptations she makes in the upper register. Her teacher often reminds her to increase air support as she ascend; scaling ladders and scaling registers both demand effort. We usually think supplying faster air or more ample air is an important part of ‘holding up’ the pitch of the upper registers. I’m going to present a slightly different take on all this.

Balance, Bassoon Reed Physics

Unless our reeds are too sharp [Baby Bear!] and stuffy, it’s usually not a problem to get a lot of sound in the lower fundamental register. In fact, most reeds with optimal compliance produce more sonority at the lower end and less at the top. The bassoon is a bottom-heavy instrument. Flutists, who struggle with the bottom octave, are frequently jealous of the ease with which we can honk out low Bbs, though flutists have a relative advantage in the upper octaves.

LB’s teacher demands she practice her scales with a bit of crescendo in the ascent and a corresponding diminuendo in the descent. This guidance isn’t because ascending phrases always require expressive growth or descending phrases always require diminishing tone, although that is frequently appropriate. Rather, the habit of adding more support in an ascending passage is a strategy to correct the imbalance inherent to bassoons: loud and edgy at the bottom and squeezed at the top.

Chapter 13 examined the acoustical reasons for this diminishing sound profile.Each step to a higher register is achieved by eliminating a strong lower harmonic; sonority can suffer as we optimize the remaining higher frequency resonances. Increased embouchure damping reduces the richness of sound by reducing the cumulative energy of these remaining harmonics. Even modest damping changes the contours of the membranes and thereby increases inertia. As we move to higher frequencies, the slight closure of the reed not only alters the MCA value but changes how the blades respond to the Bernoulli effect. Tenor register pitches in particular become less responsive to nuance and articulation.

How does our little bassoonist respond to this? By increasing air supply. Mimicking a crescendo during an ascending scale compensates for the reduced amplitude of the reed membranes. If we must lose the 1st and 2nd harmonics and all their energy, we need to rebalance input air supply simply to maintain the impression of even dynamics.

 

LB is sometimes confused by these discussions. The balance between air support and embouchure can be minefields in the pedagogy of both playing and reed making. She aspires to play in the third octave by moving the air faster, but she sometimes expects too much. Most reeds required a bit of help from the lips.

I think we can take some reassurance from the laddered acoustics that I outlined in Chapter 13. Ascending the registers demands a certain amount of embouchure damping which needs an increase in air supply to compensate. I’ve seen many young players get into throat and upper body tensions by over-reliance on air as the only tactic for holding up the upper register. I’m not necessarily advocating for larger MCA value reeds – effortless reeds are deeply appealing!! But embouchure serves a critical role in climbing the ladders. Reed making demands adaptation to the changing conditions of cane, weather, repertoire, performing environments and our emotional state. Respecting the physics will lead to better strategies in solving our reed challenges.

laddered bassoon accoustics

Chapter 10 saw our little bassoon character inside a huge, imaginary reed.

Climbing back inside, LB observes in slow motion the blades flexing. There are changes in the overall shape of the membranes as the player moves from low register to high register. In addition to an observable reduction in the aperture gap, she sees a reduction in the flapping motions in the wings. This concave collapse of the wings results from increased embouchure pressure, which transfers into these wider, thinner areas of the membranes. When blades are held a bit tighter, larger motions are restricted and help dampen the lower harmonics as well as move the reed into a Mama Bear or even Baby Bear dimension.

 

 

Wider flexing motions feed the lower harmonic standing waves for any bore length. Our typical reed profiles encourage functional concavity in the wings, reducing the amplitude of lower frequency vibration. Damping those wider motions reduces the lower harmonics in the dialogue. This strategy of damping the lowest available modes helps the reed more efficiently supply energy when we are utilizing higher bore resonances. As we climb the ladder past the 2nd harmonic area and up into the tenor range the embouchure, plus the manipulation of half-holes, vents and cross fingerings, helps eliminate the 1st and 2nd bore harmonics and allow for control in the upper range of the bassoon. My Chapter 12 assignment demonstrates this behaviour with all but the most extremely light reeds. You played the reed with your lips over the 1st wire and observed what happens as you climb the ladders. The pitches may continue to operate up into C4, but you will almost certainly find the bassoon reverting to its lower modes and sounding like a dying porpoise.

If you go back to the lips over wire exercise I suggested in Chapter 12, you will no doubt realize that if you blow REALLY hard, you can indeed extend the operation of the bassoon well up into the top of the third octave. It just takes a heck of a lot of air.

Repeating the experiment with lips on the reed but with only enough embouchure to seal the air will have taken you a little bit further – depending on how light your reeds are. But rather instinctively, we tend to dampen the embouchure and increase air support as we ascend.

But….

LB remains slightly confused. Surely, she thinks, accelerated air supply must have an effect on pitch!? And indeed, it does.

Air speed

This is a very confusing phenomenon, because in other instruments excessive volume tends to lower pitch. We see this flattening effect in the clarinet when it’s overblown. However, the bassoon will usually sharpen with increased air flow. We see this in vibrato production when the intermittent acceleration of air several times a second not only causes repetitive increases in volume but also in pitch. Sufficient air flow into a bassoon reed will also sharpen the upper bore resonances, and at an exaggerated rate! In fact, the intonation effects of embouchure and air increase substantially as we move into higher bore resonances. That’s why vibrato is so hard to temper up high, and pitch bending in the high register can be so extreme. The physics are elusive, but we presume that increased air velocity through the aperture must raise the natural frequencies of the membrane ‘shell’ as well as cause greater inward displacement of the blades and decrease that theoretical missing conical aperture. So, there’s absolutely real physical reasons why air speed might sustain both register and pitch. The evidence is with us constantly.

Next week, in Chapter 15, we are going to explore Resonance. It may not be what you think…

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation  Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven  Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift  Doodles & Design by Nadina

 

 

Brains and Membranes by Christopher Millard – Chapter 13 – Stairway to Heaven

Brains and Membranes by Christopher Millard – Chapter 13 – Stairway to Heaven

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 13 – Stairway to Heaven

In Chapter 12, I left you with an assignment: try playing the full range of the bassoon with no help from the embouchure.  The test reveals the critical role that the embouchure plays in controlling for register and tuning.

From an acoustician’s point of view, the embouchure ‘dampens’ many of the natural harmonics of the reed itself and allows the ‘standing waves’ within the bore to control the dialogue.  I’ll touch below on this subject. For this and the following chapter I’ll focus on the need for embouchure damping in controlling both the MCA value (Missing Conical Apex, Chapter 11) of a reed and helping the complex fingerings of the bassoon select for the correct register.  This chapter puts our little bassoonist to work with ascending scales and helps her understand why embouchure damping is a necessary component in tone production.  But we’ve got to dive into some tricky areas.

If you get stuck, take a break and do an online search for videos and animations of both transverse and longitudinal waves, with special emphasis on standing waves.  Videos using ropes will show you how simple it is to visualize harmonics of transverse waves; videos using Slinkys or animations are especially helpful to us as wind instrument players.

Our little bassoonist loves to play scales.  Even melodic minors…

‘Scale’ comes from the Italian word scala, meaning a ladder or staircase.

LB loves climbing up and down her bassoon ladders, especially when they take her all the way to high E and F.  But all this investigation of trampolines, caves and missing cones has got her wondering.  How does the bassoon manage to operate over three and half octaves and what role does the reed play in the process?

Let’s start by reminding LB of the conga line image in Chapter 3.  Compression waves move forward and then reflect backward from the open end of the bassoon.  Longer bores operate slower conga lines.   She understood that pretty easily.  We can also tell her that the term ‘fundamental’ is just a way of saying that a conga line has a lower limit to its frequency. The conga line for a low A can rock back and forth 110 times a second, but no slower.   To be clear about the terminology, we say ‘the fundamental resonating frequency is the 1st harmonic.’

For an explanation of ‘standing waves’ and an introduction to nodes/antinodes skip to the end of this chapter.

Consider the first 20 notes of the bassoon scale from low Bb [Bb1] to open F [F2].  This is where the bassoon bore operates in its ‘fundamental’ register using the lowest possible frequency for a given length of tube.

LB takes a big breath and begins playing a low G. Whether she plays loud or soft the pitch is predictable and constant.  The length and volume of that low G bore has a natural resonating frequency of @98hz, which we call a ‘bore resonance’.  Just like beer bottles, many enclosed spaces have natural resonances.  The amazing thing about wind instruments is that multiple bore resonances will occur simultaneously.  For that low G bore volume [designated G2] there will be a second resonance operating at twice the frequency – 196hz [G3].  It’s like a superimposed conga line on the same dance floor! A third resonance will occur around 294hz [D4], another at 392hz [G4] and there will be many more.  All these other resonances are related to the G2 in predictable ways; they are all harmonics – or overtones – of that 98hz conga line.

Nature blesses us with a really simple rule for calculating the frequency of these harmonics, based on a simple formula.  LB, a very clever bassoon avatar, notices the relationship between the harmonics:

  • 98hz X 2 = 196hz [the same as G3!!]
  • 98hz X 3 = 294hz [that’s a tenor D!!]
  • 98hz X 4 = 392hz [same as high G!!]

Even without her digital calculator, which she left in the bear’s house, she figures out the next harmonic ought to be around 490hz – which happens to be pretty close to a high B.

With her reed placed on the truncated end of her bocal, LB continues playing her low G, but begins to really listen!

She realizes that all this warm, complex, mysterious, colourful, engaging, resonant bassoon sound that she loves is uses a broad spectrum of overtones cooperating with that low G2 bore volume.  Harmonics are what gives the bassoon – and all acoustic instruments – their character

LB closes all her keys and plays a low Bb, then B & C, slowly climbing the 20 step ladder that takes her to open F.  Listening more deeply than she ever has before, LB starts to hear some of those higher components.  They are participants in the harmonic series, sounding octaves, twelfths, and compound tenths and many more.  Each note on her bassoon seems to have a slightly different balance of harmonics which just adds to her infatuation with the instrument.

These 20 notes are rich in the 1st order of harmonics for each length of bore.  So, LB asks, if the first 20 notes are in the fundamental range, what happens with the 21st note and higher????  She reaches the open F and steps onto the first balcony of the bassoon house.  There is a new ladder leading up from here, a bit shorter and a bit less sturdy.  The first rung is marked “F#3” [half-hole F#].   Cleverly perceiving the pedagogical scale metaphor, LB sees she can no longer rely on the big 1st harmonic ladder anymore because her first finger half-hole “collapses” the standing wave for the 1st harmonic.  From here on up those lower 20 notes are silenced.  Stepping on the first rung she sounds the F#3 frequency of 185hz.  She senses there is a 1st harmonic wanting to burst through that open first finger, but she understands she’s left most of it on the 9th rung of the first ladder.  She climbs step by step.  G3 and G#3 are all based on the same length of tube as G2 and G#2, but the half hole leak muffles their 1st harmonics as well.  A2 briefly tries to reassert itself when she attacks A3 [220hz], but LB quickly opens the whisper key vent and uses a flick key to discourage the brief 1st harmonic croak.  She uses similar tricks on Bb, B and C.  C#4 and D4 complete the climb through the 2nd harmonics and she steps out onto the second balcony.  Someone is practicing the Berceuse above her.

bassoon

“Crap.  I should have stuck to the flute.  All those 12ths were in tune.  Don’t tell me this tenor F4 is another sharpened 3rd harmonic resonance!!”

From her second balcony perch, LB can see that the first ladder is a kind of first generation, the next ladder a very cooperative second generation and now she has to climb a third generation ladder based on removing two lower harmonics.

With Eb4 [311hz] she begins the climb to the third balcony. This ladder is shorter still and looks a bit rickety; the rungs are flimsy are not evenly spaced. This third ladder traverses the tenor register of the bassoon and things get a bit kooky. Although she’s never really taken the time to look at her fingers, she sees that tenor Eb uses almost the same fingering as G2 and G3. She simply adds a couple of big leaks in the air column by lifting two fingers, which immediately silence the resonances of the G2 and G3 harmonics. The 3rd harmonic in a series is a simple calculation: 3 times the frequency of the fundamental. So why does this fingering not deliver 294hz [D4], a nicely predictable 12th like on a string instrument. What’s going on?

 It would seem logical to LB that the 3rd resonance for the low G fingering would create perfect 12th, but the bassoon won’t behave. Opening tone holes will coax that 3rd resonance frequency. However, the truncated cone of the bassoon bore, the contributions of tone hole volumes and variations in conicity conspire to make this next harmonic sit sharper than predicted. LB’s tenor Eb fingering is setting up a standing wave at about 311hz which is a half step higher than the expected 3rd harmonic.

A term often used here is the concept of the ‘ancestor’ note.  Tenor Eb is based on bore resonances derived from its ancestor fingering for low G.

Only slightly confused, LBS takes the next step on the ladder – E4 – tenor E. Looking carefully at her well-practiced fingerings, LB sees that this bore volume E is really similar to G2 as well!!! But she has spread out the air column leaks by lifting her LH second finger [and perhaps one or more of her RH fingers as well]. Like most of her bassoon pals she opens the low Eb key on the long joint to darken the tone and bring the pitch down a bit. Nevertheless, it immediately occurs to her that the ‘ancestor’ for E4 must also be G2!! In other words, the basic air column for low G is serving as the ancestor for both half-step sharp AND a whole-step sharp 3rd harmonic resonances. The precise pitch depends on some minor fingering tweaks.

LB is starting to really freak out, but she takes another step up to the dreaded tenor F.  She hates this note.  Then she looks at her hands and sees that she’s playing A2 and making a big air column disruption by opening her LH middle finger.

 


 Of course, she’s right. That critical second finger leak disrupts the bore resonances for the 1st harmonic A2 and the 2nd harmonic A3. Because of deviations in the bassoon design the next available bore resonance is once again a half-step than predicted. Well – not quite a half-step. Instead of sitting comfortably around an ideal F4 of 349hz, the typical bassoon F4 wants to sit in the 345hz range. So, LB has to use more embouchure damping, reducing the MCA value and stiffening the reed membranes to get tenor F to sit high enough.

She takes another step and moves to F#4. There are two basic fingering options on the German system bassoon; one uses right thumb Bb and the other uses RH 4th finger. LB starts with the thumb Bb fingering. It’s actually comfortably in tune with a resonance close to an ideal 370hz. A careful examination of her fingers shows that she’s really just playing Bb2 and disrupting the two lower harmonics of Bb2 and Bb3 by lifting the first and third fingers of her left hand. [She often substitutes the RH 4th finger F key for the RH thumb Bb, a fingering more in vogue among modern players. Regrettably, it’s a bit of an acoustical anomaly and it’s difficult to calculate its ancestor fingering in the fundamental register.]

 Adjusting to the altitude, LB now steps up to G4. She always likes this note because the bore resonance sits at @394hz and she doesn’t need to hold up the pitch like she did on that funky F4. Now she’s curious about high G’s ancestor note. She realizes that by closing her half-hole she can get the 1st harmonic for this odd fingering to sound. It’s a resonance similar to B2 but then made a quarter-tone sharp by the addition of the low F key. Yep, another compromised 3rd harmonic, but one with less resistance and sitting high enough to feel comfortable. She’s grateful for these creative cross fingerings.

Looking at the first five rungs of the third ladder, LB comprehends they are all 3rd harmonic bore resonances and all acoustically compromised. Yet a HUGE amount of her life as an aspiring bassoonist will be focused on this tenor range. More than any previous notes on the first two ladders, LB realizes that controlling intonation and sonority for these tenor range 3rd harmonic notes requires constant attention to both embouchure and air.

The acoustical anomalies that creep into the upper half of the bassoon require gradual shifts in the dialogue between bassoon and reed.  Altering the compliance of a reed is a necessary precursor for the selection of the higher bore resonances, let alone playing them in tune.  Without some change in the behaviour of the reed – in size and stiffness – the addition of half-holes, open whisper keys, various extra tone hole openings and complicated fingerings are still not enough to allow for controlled sonority and workable intonation.

While increased air supply is a fundamental requirement for climbing the bassoon ladder, some amount embouchure damping – either a little or a lot depending on your approach to reed making – is a necessary support for all those hard-learned fingerings.

Next week, in  Chapter 14 – Reed My Lips – LB finishes her climb up to the Sacré and Ravel Concerto balcony.  We’ll get back to the Bears, MCA theory and begin to look at the behaviour of cane in reed membranes.

Standing Waves – ye olde quick discourse

Standing waves are a bit difficult to visualize without an animation; they are what happens when a wave moving forward bounces back from an open end as a reflective wave, which then interacts with the energy of the following forward moving wave.  This creates constructive and destructive interactions which lead to the reinforcement of positions where high pressure or low pressure dominate.

 

This image shows the standing wave positions for the harmonics on a string.  It’s essential to make the leap from these transverse waves to longitudinal waves.  Our recurring conga line image is a simple way to think of this.

The conga line will carry a pressure wave forward [incident wave] and backward [reflective wave] to and from the open tone hole.  When those back and forth waves start messing with each other you get areas in the line where the dancers’ motions are constructively amplified and other areas where their motions are restricted.  The ‘big motion’ areas are ‘antinodes’ and the ‘minimal motion’ areas are ‘nodes’.  Any given bore length will tend to set up a conga line where the nodes and antinodes are in predictable places due to the interaction of the back and forth waves.  Because those nodal [not much motion] and anti-nodal [lots of motion] dancers each tend to congregate in their respective stationary positions, we use the term ‘standing wave’ to describe their choreography.

A bassoon bore conga line with the minimum number [1] of ‘antinodes’ and ‘nodes’ will create the 1st harmonic for that length tube. Remember, in the conga line metaphor the dancers represent zillions of air molecules pushing and pulling at each other.

The standing wave behaviour in the first 20 notes brings a lot of energy to the 1st harmonic, but there are other standing waves – harmonics -that want to occupy the dance floor at the same time. The bassoon bore has ‘resonances’ – frequencies that it really likes – all vying for the participation of the molecular conga line dancers. These resonances are closely related as they represent standing waves with progressively increasing numbers of nodes and antinodes. Any of the 20 fundamental bassoon pitches will contain overlapping and coinciding resonance frequencies. They are organized in fairly logical and discrete ways.

By the way, I will address in future chapters a very interesting quirk of the bassoon in its fundamental range. Towards the bottom end, we often measure a fairly weak 1st harmonic, despite the fact that we hear it very clearly. This a psychoacoustic effect where our auditory processing combines the input of 2nd and 3rd harmonics to create the perception of a strong fundamental resonance. This becomes an important conversation when discussing control of sonority, nuance and pitch perception in several critical musical applications.

 

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation  Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven  Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift  Doodles & Design by Nadina

 

 

conga line, standing wave

Stand-n-Wave!

Brains and Membranes by Christopher Millard – Chapter 12 – The Goldilocks Dilemma

Brains and Membranes by Christopher Millard – Chapter 12 – The Goldilocks Dilemma

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 12 – The Goldilocks Dilemma

In a simple house in the forest lived three bears.  One morning, their porridge proved too hot to eat, so they went for a stroll.

Papa Bear was rotund, gruff and loved to bark out low Bb’s.  Mama Bear, though not exactly petite, had an alto voice particularly adept at cantabile.  Baby Bear, who was not quite a teenager, was a bit of jackass.  He loved to scream in a high falsetto just to irritate his parents.

Goldilocks, looking a whole lot like the Little Bassoonist of previous chapters, just happened to come upon their forest home.  She was ravenous and smelled the porridge.  Using her trusted forming mandrel and reed pliers, Goldie breaks open the Bears’ front door.

On the table are three bowls, each with a bassoon reed for slurping.  Goldie goes to the big bowl first, tastes the porridge then blows on its large reed.  A deep, rattling crow emerges.  Then she tries the middle-sized bowl with its middle-sized reed.  It’s definitely more refined and produces a tamer tone.  Finally, she pops the little reed in her mouth and a much higher peep sounds.

Holding all three reeds, Goldie walks into the bedroom and proceeds to lie down on each of the three beds.   She contemplates a deeply existential question: how to reconcile her passive-aggressive nature with the adorable image that she’s been cultivating as a pedagogical avatar in an instructional series on bassoon reeds.

And she can’t decide which bed she likes.

Highly introspective, Goldie recognizes that the narrative portrays her as an archetypal spoiled brat with an empirical bent.  For the sake of the story she ought to just choose the mid-sized bed and mid-sized reed. But that very week her orchestra has scheduled Peter and the Wolf, Tchaikovsky 4thSymphony and Le Sacré du Printemps for its gala concert.  Apprehensive, she decides to keep all three reeds.  Exhausted by all the rumination, she falls asleep, is discovered by the bears and summarily chased from their house.  Well, it’s a fairy tale so we can’t have a mauling…

Goldilocks needs the perfect reed.  Why did she keep all three?

Anyone who has spent years in a symphony orchestra knows that particular musical challenges need a certain kind of reed.  Bassoons are an evolutionary oddity and they often need reeds whose input/output response is maximized to a particular register.  Like it or not, the low register is more acoustically efficient with a flatter reed.  As we move up the octaves, response, tuning and sonority tend to be maximized with gradually sharper reeds.  It’s a bit like using a #3 bocal at the bottom, a #2 for the mid-range and a #1 for the high register.

Papa Bear’s reed likely has a larger MCA value (Missing Conical Apex, Chapter 11) and offers nuance, dynamic range and efficient input response in the bottom range of the bassoon.  Mama’ Bear’s reed matches the ‘money register’ of the bassoon where so many of the important lyrical solos live.  Baby Bear’s reed has an even smaller MCA value, ensuring success with the highest register.

I generally avoid playing the Pathétique symphony on the same reed as Ravel’s Piano Concerto in G.  In fact, I often wish I could simply swap reeds as I ascend and descend the large tessitura of the bassoon!  Wait a minute, you might say.  Solo repertoire for the bassoon jumps ALL over the place.  I agree, and we always try to make a one-size-fits-all reed for much of our work.  Nobody walks into an orchestral audition and switches reeds for every excerpt [all this can be a good strategy in limited circumstances!].  But when we’re not performing the Jolivet Concerto and want assurance of predictable control in the orchestral environment – for pianissimo low E or crack free attacks in the altissimo register – we have to adjust our reeds to be reliable for the task at hand.

Let’s delve a bit deeper into the Bears’ individual behaviour.

Papa weighs 700 lbs, can crush a cast iron skillet with his teeth and inflate a dump truck tire with his breath.  Being a big, aggressive bear, he has no trouble playing fortissimo low Bbs.

He’s naturally comfortable using a lot of embouchure, so he’s quite capable of playing una furtiva lagrima when he’s feeling amorous. Embouchure pressure goes hand in hand with strong abdominal muscles; clamping down decreases the compliance of the blade membranes, and increases resistance to input of air.

Mama weighs 500 lbs and has a slightly gentler breathing apparatus.  Her alto voice matches the mid-range of her bassoon and she prefers a more relaxed embouchure for her Tchaikovsky 4 solos.  She admits that she gives up some dynamic range at the bottom end but prefers to play reeds that don’t necessitate a daily shot of B vitamins.

Baby weighs 150 lbs.  He’s not a teenager yet and his voice hasn’t broken.  He can easily attack high E’s with reliable control, but he tends to stay sharp and dynamically constricted in the bottom half of the bassoon and his staccatos are not always clear.

Bassoonists have widely differing preferences for the use of embouchure.  There are those who build reeds that require only subtle lip effort and sing quite effortlessly in the upper half of the bassoon range.  Others naturally use a lot of embouchure and are happy to do so.  There are great outcomes and great players at the extremes of both of these camps. Most bassoonists have reed making lives that flow back and forth towards one end of the spectrum or the other. However, we should explore the advantages and disadvantages to each of these approaches.

Experienced bassoonists know how frequently we wish reeds were either flatter, sharper, darker, brighter, more open or more closed.’The MCA theory  is one part of the puzzle because it gives some guidance about how to develop your designs and your trims.  Although it’s a rough tool, the theory encapsulates the dialogue between bore and pressure valve. Compliance’ describes how the membranes of reeds fulfill their responsibility for any given note, dynamic and musical nuance.  That complex meeting of output response needs and input response mechanics determines the degree to which our reeds serve our musical needs.  We’ll look more closely at the relationship between tuning and tone in future chapters.

Next week, I’ll explain some basic ideas about the behaviour of harmonics in different bassoon registers.  In preparation for that, I’d like you to try an experiment that may illuminate the role of your embouchure.

Take several reeds – Papa Bear, Mama Bear and Baby Bear if you can find that much range in your reed box.  Place your lips over the first wire so that your embouchure has no contact with the top and bottom blade membranes.  Play ascending chromatic scales on your bassoon from low Bb up to high D.  The bigger reeds, those with a larger MCA value, are going to give you problems around Bb 4 [top of the bass clef staff].  Reeds smaller MCA values – sharper reeds – may allow you to play much higher into the 3rd register.  If your reeds are tending to be small and sharper, an easy way to get a Papa Bear response is to remove the 1st wire.  Alternately, takes pliers and open the reed up to create more internal volume. If your reeds tending to be large and flat, tighten the 1st wire, clip the tip, narrow the sides or do anything to reduce dimensions or raise the pitch of the reed.

Your natural instinct when larger reeds start breaking up in the tenor range is to blow harder.  Indeed, that may allow you to get a few more ascending notes to function.  When the upper half of the instrument starts breaking up, you’ll get a drop down into the lower register and likely have some ugly multiphonics as well.  Smaller sharper reeds may allow you to play up to the altissimo register, but they will usually feel constricted at the bottom.

This experiment will help you to evaluate where you might be on the spectrum of Papa Bear through to Baby Bear reeds.

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation  Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven  Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift  Doodles & Design by Nadina

 

 

Pesky humans

Brains and Membranes by Christopher Millard – Chapter 11 – A Useful Equation

Brains and Membranes by Christopher Millard – Chapter 11 – A Useful Equation

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 11 – A Useful Equation

I hope you are getting comfortable with visualizing the relationship of the reed to the bassoon.  This holistic idea is something we will return to often.  But for now, let’s move on to a basic design principle. Size.

Remember our little bassoonist, stuck inside the enormous reed cavity in her dream?  All the space around her constitutes an extension of the bassoon bore.

Bassoon bores have a fairly consistent rate of taper; they are conical and therefore should eventually come to a point – an apex.  That would be fine for our beer bottle sound production, but we need the energy generator of the reed, and it needs to fit onto the small end of the bassoon.  So, we take a nicely tapered  cone and truncate it by lopping off the first 25cm of the bocal.

The bocal has a Missing Conical Apex (MCA).

It’s useful to imagine what varying that missing apex might do to the pitch outcomes for the bassoon as a whole. We know that longer bores are flatter and shorter bores are sharper; the essential factor is volume.

A longer reed, a wider reed or a more open reed represent increases in the internal volume of the reed.  If we consider a static, non-vibrating reed, it should be really simple to calculate the MCA of the bocal and build a reed with identical internal volume.  The problem is, reeds can’t be static.  They must be compliant – which is the whole point!

In fact, the reed cavity volume in any bassoon reed is WAY smaller than the theoretical MCA of any bocal. The actual internal volume of a typical reed would make it unplayably sharp if there were no modifying factor.

So, what’s missing in our analysis?

It’s the compliance of the cane.

We can express this most basic concept in different ways:

If you consider the flexibility of the membranes in the context of the internal volume of the reed you will come up with a functional equivalency.

…which is to say…

If you take a given dimension of reed and alter its compliance you will come up with a system that satisfies the missing bore volume at the tip of the bocal

…which is to say…

There are two balancing factors in designing a reed that serves the bassoon at A-440; size and behaviour

…and so forth…

   Let’s simplify this and use an equation:

  RV x C = MCA

  RV  means ‘reed volume’ and this is determined by how big the reed is in three dimensions (length, width, height aka L, W, H)

  X means ‘is modified by’

  C means compliance, which is an acoustician’s way of talking about overall elasticity, flexibility, stiffness, springiness, hardness etc.

   = means ‘gives an approximation of

  MCA is the idea that a truncated bassoon bore needs a reed valve that will function as the equivalent of the volume of the missing bocal tip.

  If you recall the idea of Dialogue in Chapter 8, you could say that one partner in the conversation (the reed) has to be particularly flexible and engaging.

Let’s try out the equation and see whether it makes sense in terms of your own reed making experiences.  We’ll plug in some ballpark figures.

Reed volume – you can actually test this volume with a syringe and find reeds ranging from .75 to 1.5 milliliters capacity

Compliance factor – suppose a scale of 1 – 10, where 1 is absolutely stiff and 10 as flexible as possible

MCA – We think of this in terms of functional pitch, not an actual numeral. But assume that a larger MCA will deliver something like A=440 and a smaller MCA will tend to A=447.  Just remember, a larger missing conical apex volume will be flatter in pitch than one with a smaller MCA.

So, for the sake of argument we take two reeds of identical design but different compliance:

Reed A: RV [.95] X C [4] = MCA value [3.8]

Reed B: RV [.95] X C [6] = MCA value [5.7]

In this example, both reeds have identical internal volume, but Reed A is less compliant and produces a smaller MCA value.  In normal language, we would say same size reed, but stiffer, produces a sharper outcome.

Now let’s consider two reeds of identical compliance but different  in design:

Reed C: RV [1.05] X C [5] = MCA value [5.25]

Reed D: RV [1.30] X C [5] = MCA value [6.50]

In this example, Reed D has a larger internal volume and produces a larger MCA value.  In normal language, we would say similar compliance reed, but larger volume, produces a flatter outcome.

These simple models probably reflect some of your own experiences.  If we take two similar reeds and make one more flexible it will tend to play a little flatter.  And if we take two similar pieces of cane and similar profiles, the smaller reed tends to play a little sharper.

RV, reed volume, is defined primarily by length and width.  Height [openness] is a third factor but really confuses things for reasons we will dig into in later chapters.

You will have had experiences with reeds that are too flimsy and flat, with certain notes collapsing too easily (1st finger E and wing C#s are the first to go…)  When you clip a tip, you are reducing the internal volume of the reed, and reducing the MCA value creating a sharper outcome.  And if you make a reed narrower, you will usually find it easier to hold up the pitch.  If all your reeds are too sharp, you will probably start increasing your length and the width of your cane.

Of course, anything  you do to the dimensions of a reed will have unavoidable effect on its compliance. Clipping a tip not only raises the MCA value due to a reduction of internal volume, but also due to a reduction of compliance.

In the next chapters, I’ll talk about how responses are associated with adjusting the MCA value.  I hope what will emerge is a realization that tuning and tone are irrevocably linked.

Eventually, we will come to discuss the often paradoxical observations that emerge in sophisticated reed making. These reflect the intersection and conflicts of some acoustical principles, especially the often competing physics of fixed bars and shell membranes.

But next week, a return to make believe.

Chapter 12 – The Goldilocks Enigma

 

 

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation  Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven  Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift  Doodles & Design by Nadina

 

 

Why, MCA!

Brains and Membranes by Christopher Millard – Chapter 10 – The Incredible Shrinking Bassoonist

Brains and Membranes by Christopher Millard – Chapter 10 – The Incredible Shrinking Bassoonist

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 10 – The Incredible Shrinking Bassoonist

Our little bassoonist is tired from all that Milde on the trampoline.  Exhausted, she falls into a deep sleep.

And she dreams.  Of Milde, melodic minors and Mozart.  Of straight shapers, cut fingers and dull profiler blades.  She finds herself lying inside a cavernous bassoon reed.  Time is running ever so slowly. She looks up to see the gently curving arches of the upper membrane, a mirror image of the lower blade on which she sits.  She gazes back down the dark tube of the reed into the blackness of the bocal and feels the waves of pressure wash over her.

From the enormous aperture, our brave little physicist/bassoonist feels a gentle breeze blowing.  But she is mostly aware of the compression/rarefaction waves behind her – moving at the speed of sound and riding the in-coming airflow like a wave on a river current.

In her dream, time continues to slow.  Cocooned in this shell, she watches the blade membranes undulate; they are interacting with both the air flow from the player and the complex multi modal pressure waves coming from the bassoon bore behind her.  The sound is getting louder and with increased blowing pressure comes an increase in the vigour of the blades’ (membrane) contortions.

inside a bassoon reed; compression and rarefaction

It’s a fascinating revelation: the dynamic increases the size and severity of the waves’ movement yet the frequency of these motions remains unchanged.

The chaos and asymmetry of the membrane activity is astounding, especially at louder volumes.

The sound of the bassoon, so warm and reassuring, seems disconnected from the complexity of the membrane functions.  She had expected the graceful curves of a cresting ocean wave. Instead, she sees alternating convex and concave ripples in the membrane; with increasing air input the blades are thrown ever closer towards each other, the aperture slamming open and shut like a screen door in a wind storm..

The milliseconds tick on. Repetitive patterns begin to emerge in the membrane behaviour, the complex irregularities are repeating over and over. Suddenly, she understands the correlation between the tingling compression waves at her back and the repeating undulations above and below her.

She is standing at the very meeting place of input and output response and bears witness to the marriage of the bassoon and its pressure-controlled valve.

As the dream unfolds, our little friend begins to hear music.  Someone is playing this huge bassoon, with dynamics and nuance, over its three plus octave range. She watches as the membranes respond to intricate control from the embouchure outside.  The compression waves slow down – the low register is asking the membranes to slow down their energy conversion frequencies.  The bassoonist must be relaxing the embouchure, because she sees the membranes open more.

Suddenly, higher pitches dominate and the bassoonist presses into the membranes, creating tension and reducing the size of the cavern.  Le sacre!!!

The dream ends…

This visualization of the internal workings of your reed will be a theme that we return to as we examine the relationship of air, embouchure and musical demands. The bassoon reed-valve needs tremendous flexibility to accommodate the numerous frequencies – both fundamentals and harmonics – produced throughout the full range of the instrument.  Just as a violin string needs to move simultaneously in both its whole length and in many divisions, the membranes must be simultaneously activated and able to move in wide/narrow patterns of motion and in slow/fast frequencies.  Viewing this action from inside the reed in our slowed-down dream, our little physicist likely observed lower frequency full side to center closures of the tip aperture and at the same time witness higher frequency displacements in narrower bands of the membrane.   The multimodal closings and openings of the valve respond to both the multiple frequencies and the varying amplitudes of pressure that the bassoon requires. In the next chapter we’ll leave dreams behind and concentrate on some core dimensional principles.

Coming up,  Chapter 11 – A useful equation

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation  Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven  Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift  Doodles & Design by Nadina

 

 

i’m having trouble sleeping now