By Jeffrey Li, Cellist
BS Northwestern University, School of Engineering
BM Northwestern University, School of Music
MM The Juilliard School
While violins and violas rely on a single bridge design, cellists have the option between two: French and Belgian. Many cellists simply stick with the bridge that came with their instrument, as changing it can be both time-consuming and expensive. However, if your cello has a French bridge, you're not only missing out on its full sound potential - you're compromising the instrument's overall performance.
Terminology: Understanding the Basics
Before diving into the details, it is essential to understand some key terms that will help understand French vs Belgian bridges scientifically:
Frequency: The rate at which a vibration occurs that constitutes a sound wave, measured in hertz (Hz), or oscillations per second. Higher frequencies correspond to higher-pitched sounds. For stringed instruments, its how many complete cycles a string vibrates back and forth in 1 second.
Fundamental Frequency: The lowest frequency of a sound wave, which determines the pitch of the note being played. It is the most prominent and thus identifiable frequency in a note.
Overtone: A higher frequency resonance that occurs naturally in a physical system when it vibrates, encompassing all sounds in nature. It is any integer multiple frequency above the fundamental frequency of the system, where the fundamental is the lowest frequency that can sustain a standing wave. In musical instruments, overtones affect the instrument's timbre, or tone color, as they combine with the fundamental frequency to create the characteristic sound of the instrument. The presence and balance of overtones are what differentiate the sound of one instrument from another, even when playing the same note.
Low-pass Filter: A signal processing device or function that allows frequencies below a certain cutoff frequency to pass through, while attenuating or blocking frequencies above it.
Dark Sound: A tone that emphasizes lower frequencies, often perceived as warm or mellow but can lack clarity and projection.
Bright Sound: A tone that emphasizes higher frequencies, often perceived as clear, sharp, and resonant, which is crucial for projection.
Decibel: A unit used to measure the intensity of a sound. Higher decibels correspond to louder sounds, whose units are notated dB. The decibel scale is a logarithmic scale, with an increase in 10 dB corresponding to a perceived doubling in volume.
Why Every Cello Needs More Sound, Especially in Ensemble Playing
Acoustic Power of a Cello
"I just wish this cello weren't so loud" said no one ever. On the decibel scale, the loudest violins and violas can reach 95 dB, concert grand pianos 110 dB, and trombones 115 dB. Even the most exceptionally loud cellos however top out at 82-85 dB maybe, which is less than half the volume of a violin. Most cellos achieve closer to 75-80 dB. While instruments aren't always played at maximum volume, the cello is easily drowned out in any ensemble even in mild playing conditions, especially with its range overlapping others.
This doesn’t mean cellists should play fortissimo all the time for obvious artistic reasons, but will inevitably struggle more in rehearsals and on stage where other instruments are naturally louder and may be unaware of the acoustic challenges cellists face. While this can be mitigated with polite etiquette during rehearsals to adjust balance, cellists are ultimately at the mercy of other instrumentalists' readiness to accommodate.
Bias in the Human Ear's Natural Hearing Range
The human ear is naturally more sensitive to the frequency range between 2,000 and 5,000 Hz, where the overtones of speech and many everyday sounds occur. This heightened sensitivity is due to the ear's anatomy and its evolutionary adaptation to detect sounds that are crucial for communication and survival. Frequencies within this range are perceived more clearly than those outside it, making them stand out even in noisy environments. This selective hearing ability influences how music and sounds are perceived, with instruments and voices that emphasize these mid-range frequencies typically being more prominent and easier to hear.
The vast majority of the cello's playing range of fundamental frequencies in the standard repertoire is around 65 Hz, the open C, to around 1,500 Hz near the end of the fingerboard, spending the most time on notes well below 1000Hz, and only during fleeting moments glancing 2,600 Hz such as the last note of Prokofiev's Sinfonia Concertante.
The lower overtones in string instruments are the loudest, decaying by about 12db per octave. This means a fundamental frequency played at a maximum 80dB, has only 56dB remaining by the 3rd overtone (2 octaves above the fundamental frequency) —the volume range of normal conversation between two people, and any higher overtone, thus quieter, approaching the levels of background noise. When considering the 3rd overtone's frequencies, which multiplies the fundamental frequency by 4, puts their range between 260Hz to 6000Hz, with the majority of the notes being much lower, barely cracking into the human ear's most sensitive range.
Meanwhile the violin's range starts life an octave and a fifth above the cello, triple the frequency range, putting a violins usable fundamental range at 196Hz to 2000Hz, just breaking into the 2000-5000Hz range, with its powerful low overtones squarely within it. Combined with over double the volume on tap at 95dB a violin can effortlessly overshadow a cello.
What A French Bridge Does to a Cello
Any bridge transfers sound energy from the vibrating strings into the cello's body for amplification. A French bridge specifically, with more mass near the top where the strings contact, acts as a low-pass filter. It allows lower fundamental frequencies and overtones to pass while attenuating and reflecting higher frequencies away from the cello, preventing the string-produced high overtones from ever entering the body of the cello for much-needed amplification.
This result is a darker, warmer tone but sacrifices clarity and projection, particularly in the cello's overtones that finally break into the human ear's most sensitive range. But what happens to the overtones that are reflected away from the bridge? They bounce right back, creating shrill sounds directly under the player's ear, while the audience farther away is left with weak tone lacking in projection.
The Superiority of the Belgian Bridge
The Belgian bridge on the other hand allows for more efficient vibration transfer from the strings to the body of the instrument, whose design emphasizes higher frequencies, leading to a brighter, more focused, and ultimately louder sound.
High overtones define superior clarity and articulation, which are non-negotiable when the instrument needs to cut through an orchestra or reach the back of a large concert hall. The thinner legs and more pronounced arch in the Belgian bridge contribute to quicker response times and better articulation, making it the preferred choice for professionals who need their instrument to respond to the subtlest nuances of their technique. It’s no coincidence that virtually all professional cellists choose Belgian bridges for their setups. When performing on the world’s biggest stages, every sound advantage counts.
In playing tests to identify high-performance cellos, those with French bridges only occasionally outperform their Belgian counterparts in the lowest register, but lose in every other aspect. Cellos with French bridges are often harder to sell to serious cellists due to the reluctance to the high overhead time cost of cutting a new Belgian bridge, retesting the cello against the ones that won against it. While it will certainly out perform itself with a Belgian bridge over the French, there's no guarantee it would be enough to outshine the other cellos that won in the first place.
The French Bridge: An Unintended Tool for Beginners
Ever notice that beginner student cellos, often priced under $2,500, are almost universally fitted with French bridges? While the specific reasons for this choice may vary by shop, it likely aligns with the initial challenges faced by new cellists. Beginners haven't yet developed the feel for the strings or their response under the bow arm, and when lacking bow control, leading to nails-on-chalkboard scratching sounds - aka high frequencies. The French bridge attenuates higher frequencies and reduces overall volume, making it more forgiving not only for beginners to tolerate practicing, but their neighbors too.
Conclusion - What to do if your Cello Tests Positive for French Bridge
Sound quality doesn't matter if it can’t be heard. While it may be tempting to put a French bridge on a brighter-sounding cello thinking it will mellow it out, warm sound should be created by bolstering bass frequencies to give cellos more punch, not by reducing overtones, taking away from precious volume and clarity. Bright sound, when necessary, should be managed with technique and setup. While technique is up to the player, setup can be achieved by an experienced luthier modifying other parts of the cello before considering such a drastic compromise as a French bridge. Unless you plan only ever to play solo in small, quiet rooms, your cello needs a Belgian bridge.
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