# Intentional Losses at Music Instruments



## Enthalpy

Hello nice people!

Some thoughts here about not so rare cases where *losses are desired and intentional* on music instruments.

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Several tone holes contribute to emit a note on woodwinds. Even the flute's huge holes don't stop the downstream vibrations: F# fingered with 2R is muffled, 3R instead opens a second hole and is clearer. The oboe's and bassoon's narrow holes increase the effect, and for some notes, bassoonists move a key downstream 4 consecutive open holes to ease the emission or correct the intonation. A theory exists for that.

At quarter wavelengths much larger than the spacing, the holes concur to vent the air column and act as one bigger hole. But at higher notes or overtones, the forth and back distance put the reflections out of phase, so they add badly. Venting the column would need more air speed at all holes as they act uncoordinated or even against an other, but losses at the holes prevent that. Consequently, the reflection is weaker at the higher overtones, and so is the resonance of the air column.

I claim this effect is sought to dampen the strident high sound components produced by a double reed, and sometimes by a single reed. After the success of the Boehm flute, oboes and bassoons were tried with large tone holes, by Sax, Triebert, Gautrot, recently Wolf at his bassoforte. All were abandoned because strident.

I already suggested that throat holes must be narrower so the losses match across a register jump, and a reed fits both notes. There the low sound components matter.
scienceforums​But the present effect serves to dampen the strident high components.

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The lowest notes need low losses hence large holes for decent resonance and also to match the bell. They lack the described filtering and can sound quite hard, more so at a bass or contrabass. My bassoon does it at the but-lowest note, and so did the contrabass clarinet of a known luthier.

I suggest to *split the lowest tone hole(s)* to mimic the effect of higher notes.









The relative diameters and positions adjust the effect. The split hole might even reduce the losses at low sound components.

The effect resemble the Stowasser holes at the bell
scienceforums​Maybe these improve the but-last note too.

Marc Schaefer, aka Enthalpy


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## Enthalpy

The French bassoon has many bad notes, difficult to emit and whose height can jump. Instruments more recent than mine too, as I see "More stable" alternative fingerings in books, even for notes on the 1st and 2nd registers.

One cause is the misalignment of the overtones, obvious on my instrument: by a semitone or a tone already at low partials. Known effect.

The narrow long tone holes are an other cause. They are needed as they sit very high on the air column and to soften the double reed's sound. The many keys closed at rest are an other. All this propagates the vibration far down in the air column, more so at high notes and overtones, as is known by experience and models, so very low tone holes influence high notes.

Maybe I discern one more cause. A flare at the bell suppresses the reflection of high notes and overtones at the end of the tube by matching them to the outer air. But the bassoon has no flare, so the tube's end reflects high sound components, and the tube's end is ill-placed for some notes, so it favours the overtones of notes slightly higher or lower than the wanted one.

*Stowasser's holes at the bassoon's bell* would heal this last cause by spoiling the reflection of high sound components.
scienceforums​
A similar effect happens at the (flareless) flute, where a footjoint to low B destabilizes the C three octaves higher. A "gizmo key" was added against that. Add Stowasser's holes at the flute too, if they don't reduce the needed resonances?

I ignore how much the German bassoon improves that. The right thumb has several holes under a common pad, possibly to spoil the propagation of high sound components. Could someone kindly tell me where they meet the air column?

Marc Schaefer, aka Enthalpy


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## Enthalpy

I claimed that the* chambers at the toneholes of some oboes*








serve also to dampen the strident harmonics above 4.5kHz, with figures there:
scienceforums
*
Measured spectra* show precisely what I had expected, there, at "4. Die Klangfarbe"
mdw.ac.at
from Wiener, Wiener, conservatoire and conservatoire oboes which the paper names "French". Alas, only some conservatoire oboes, mostly by French manufacturers, do have the chambers. I wish I knew what instrument they recorded.

I suggested an easy way to undercut the tone holes of varied woodwinds, compatible with chambers
talkclassical
undercutting gives the clarinet a louder and more centered tone.


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