To lefreQue or not to lefreQue?

Originally posted 9/2/2014

Last winter, my friend Matthew Harvell sent me a link to a series of Youtube videos demonstrating the lefreQue, a device that claims to improve the resonance of wind instruments.  The idea behind it is that wherever two joints of a wind instrument come together, there will be a disruption in the vibration of that instrument.  If you can remove—or at least reduce—these disruptions, then you will improve the instrument.  The lefreQue claims to do just this using two pieces of metal that act as a “sound bridge” that carries vibrations across the joints.  This was an entirely new concept to me, but I was impressed enough with the before-and-after recordings on Youtube to order a set from Maarten Vonk and find out for myself what they could do.

After receiving the lefreQue, I could tell immediately that there was an effect on tone and response.  From a player’s perspective, the feel of the instrument changes—the response seems quicker, and legato, particularly between different registers, is much improved.  Everything feels smoother and easier—but how does it sound?


My students and I devoted a studio class to trying the lefreQue on a variety of bassoons: my Walter, a 4,000-series Heckel, a 12,000-series Heckel, a Fox Renard 220, a mid-1970s Püchner, and a thick-wall Yamaha.  I played the same passage—the opening phrase from Dutillex’s Sarabande et Cortège—and used the same reed for each example.  I also tried to play each bassoon “as it comes,” without adjusting too much for pitch, to see what effect, if any, the lefreQue would have on intonation.


4,000-series Heckel

Fox Renard 220

12,000-series Heckel



As you can hear, each bassoon responds differently to the sound bridges.  The consensus among studio members was that the most dramatic effect was on the Renard 220.  Other instruments seemed easier to play without them, like the vintage Püchner.  Of course, this is an isolated test of these few instruments, and conclusions cannot be drawn about the effect of the lefreQue on different makes of bassoons.



To better understand the differences in the sound, I isolated the final A of each example and analyzed its overtone spectrum with Sonic Visualizer.  In each case, the sample without the lefreQue is on top, and the sample with the lefreQue is on the bottom.

The first analysis in each set maps the overtones and their relative strength onto a piano keyboard.  This presents a snapshot of a single instant in the sound.  Because the sound changes from instant to instant, this analysis can’t be assumed to definitively show the differences in overtones between the two examples.  However, it does represent general trends.

The second analysis, a spectrogram, shows a more comprehensive view of the sound across the duration of the entire example.  Each horizontal band represents a partial of the overtone series.  Redder bands indicate louder partials.















The lefreQue clearly affects the distribution of overtones in the bassoon sound, diminishing some partials while amplifying others.  These changes vary in both nature and intensity depending on the instrument.  In general, it appears that the second partial (the octave) becomes stronger on most instruments.  The exception to this was the Püchner, whose overtones actually seemed to weaken with the lefreQue, and which felt a bit less comfortable to play with the sound bridges on.  Interestingly, both Heckels, as well as the Yamaha did not show as much change in the overtone profile as the Walter, Fox, or Püchner.

Are these changes positive or negative?  I have not come to a conclusion.  I’ve gotten very different reactions from colleagues when performing head-to-head comparisons.  Almost universally, bassoonists seem to prefer the unadulterated sound, saying that with the lefreQue, the  bassoon sounds less interesting, less “woody,” and less “reedy”.  Non-bassoonists I have played for had a different reaction.  One clarinetist much preferred my playing the lefreQue on, calling the sound more resonant, vocal, and “like you, but better.”  In the end, I agree with both of these assessments.  I do find that my raw tone is more complex and viscerally pleasing without the lefreQue, but when I listen in the context of a musical passage, the version with the lefreQue on sounds like better bassoon playing.  The feel of the instrument—smooth with a more supple legato—is also compelling.  Whether it is worth the slight sacrifice in tonal interest is still an open question.