Hubbry Logo
Wolf toneWolf toneMain
Open search
Wolf tone
Community hub
Wolf tone
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Wolf tone
Wolf tone
Wolf tone
View on Wikipedia
from Wikipedia

A wolf tone, wolf note, or simply a "wolf",[1] is an undesirable phenomenon that occurs in some bowed-string musical instruments, most famously in the cello. It happens when the pitch, or more particularly the fundamental frequency, of the played note is close to a particularly strong natural resonant frequency of the vibration of the instrument's body.[2] Wind instruments can produce a similar effect for similar reasons—notably, in the case of brass instruments, when the played note's pitch is near a resonant frequency of the instrument's bell.[3]

A wolf note is hard for the player to control: instead of a solid note it tends to produce a thin "surface" sound, sometimes jumping to the octave of the intended note. In extreme cases, a "stuttering" or "warbling" sound is produced, as in the sound example. This sound may be likened to the howling of a wolf. A somewhat similar sound is the beating produced by a wolf interval, which is usually the interval between E♭ and G♯ of the various non-circulating temperaments.

Stringed instruments

[edit]
A brass wolf note eliminator typically placed on the G string (second string from the left) of a cello, between the bridge and the tailpiece. (The black rubber piece on the D string (third from the left) is a mute.)

The physics behind the warbling wolf was first explained by C. V. Raman.[4] He used simultaneous measurements of the vibrating string and the vibrating body of the cello, to show that the warbling sound is caused by an alternation of two different types of string vibration. All bowed string vibration is “stick-slip oscillation”. One of the vibration types involves a single slip in every cycle of the note, but the other type involves two slips per cycle.

Frequently, the wolf is present on or in between the pitches E and F♯ on the cello, and around G♯ on the double bass.[5][6] A wolf can be reduced or eliminated with a piece of equipment called a wolf note eliminator. There are several types. The one illustrated is a metal tube and mounting screw with an interior rubber sleeve that fits around one of the lengths of string below the bridge. The position of the tube must be adjusted so that the short section of string resonates exactly at the frequency at which the wolf occurs. It works in the same way as a tuned-mass damper, often used to reduce vibration of bridges or tall buildings.

An older device on cellos was a fifth string that could be tuned to the wolf frequency; fingering an octave above or below also attenuates the effect somewhat, as does the trick of squeezing with the knees.[7][8]

While it has been said [by whom?] that Lou Harrison wrote a piece (evidently reworked as the second movement of the Suite for Cello and Harp) that exploited the wolf specific to Seymour Barab's new cello,[citation needed] there is no clear evidence that this occurred.

"Naldjorlak I", composed by Éliane Radigue for realisation exclusively by the cellist Charles Curtis, is in fact composed solely around the manipulation of the wolf note of Curtis's cello.

See also

[edit]
Wolf Tone
A wolf tone on a cello
Problems playing this file? See media help.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Wolf tone

View on Grokipedia
from Grokipedia
A wolf tone, also known as a wolf note, is an acoustic phenomenon in bowed instruments, particularly cellos and double basses, where a specific note produces an unstable, or wavering sound that is difficult for the player to control. This disruptive effect typically occurs at pitches around F or F♯ (below middle C on cellos), resulting from the interaction between the 's vibration and a strong in the instrument's body, which causes periodic energy buildup and collapse in the 's motion, often at a rate of 7 to 10 cycles per second. The wolf tone arises primarily due to the instrument's corpus exhibiting high dynamic mobility at its main , absorbing more energy from the than the bow can replenish, leading to a feedback loop of amplification and cancellation between the , the top plate, and internal air vibrations. This mismatch is more pronounced in larger instruments like cellos because their bodies have lower fundamental that overlap with common playing ranges, though it can affect violins (usually at F or F♯ on the ) and violas less frequently. First scientifically investigated by in 1916, who observed that insufficient bow pressure shifts the 's vibration mode to emphasize the , exacerbating the irregularity when the belly's motion lags behind the by about a quarter cycle. Mitigation strategies include mechanical adjustments such as repositioning the soundpost or bridge to detune the body resonance, or attaching "wolf eliminators"—devices like damped resonators or tubes placed between the bridge and tailpiece that absorb excess energy at the problematic frequency without significantly altering the instrument's overall tone. These solutions, informed by acoustic measurements like transfer functions and spectral analysis, allow precise tuning (e.g., tube lengths adjusted to within 0.1 mm) to suppress the wolf while preserving playability. Despite advances, wolf tones remain a notable challenge in instrument setup, influencing luthiers' designs and players' techniques across professional and amateur contexts.

Definition and Characteristics

Phenomenon Overview

The wolf tone is an undesirable acoustic primarily affecting bowed string instruments, characterized by a , pulsating, or wavering in the sound when the of a played note closely matches a strong resonant mode of the instrument's body. This disruption creates an unstable, throbbing quality in the tone, often described as a "howl" due to its intermittent beating or fluctuation. Key characteristics include its occurrence on specific pitches, such as around F or F♯ on the , where the note becomes fuzzy and resistant to control, producing a or breathy effect rather than a steady sustain. Unlike beneficial normal , which amplifies harmonics to enrich the instrument's , the wolf tone represents a pathological interference that degrades playability and tonal clarity. Early scientific documentation was provided by G.W. White in 1915, who linked it to the alignment of string vibration with body resonance.

Auditory and Perceptual Effects

The wolf tone produces a distinctive beating or throbbing quality in the sound, often likened to a wolf's howl, arising from low-frequency amplitude modulation that creates periodic intensity fluctuations. These modulations typically occur at rates of approximately 7 to 10 Hz, resulting in a warbling or pulsing effect that disrupts the steady tone. On low strings of larger instruments like the cello, this manifests as a wavering pitch with surges and fades in volume, where the note alternates between clear resonance and unstable oscillation. For musicians, the wolf tone poses significant perceptual challenges, including difficulties in maintaining precise intonation due to the unstable vibration, which can cause the pitch to jump to an unintended octave or produce a thin, surface-like timbre. This instability reduces the instrument's projection, as the energy dissipates into erratic body vibrations rather than sustained output, leading to emotional frustration during performance. Listeners perceive the wolf tone as dissonant or ghostly, with its throbbing character evoking an eerie, uneven quality that detracts from musical coherence. Psychologically, the phenomenon disrupts phrasing and expressive control, compelling players to adapt their technique—such as employing lighter bowing pressure—to mitigate the throbbing and restore some stability. These adaptations, while effective in the moment, highlight the ongoing perceptual burden, as the wolf tone's volatility can vary with environmental factors like humidity, further complicating consistent performance.

Acoustic Principles

Body Resonance in Stringed Instruments

The body of a stringed instrument, comprising the top plate (often called the soundboard), back plate, and sides (), serves as the primary mechanism for amplifying the weak vibrations generated by the . These vibrations are transferred to the body via the bridge, which couples the string motion to the wooden structure and enclosed air cavity. The top plate, typically crafted from for its favorable acoustic properties, vibrates predominantly in a piston-like manner to radiate efficiently, while the back plate, usually made of , provides structural rigidity and contributes to higher-frequency modes through its stiffness. The sides connect the plates, forming a resonant cavity that enhances low-frequency response by coupling the wood and air vibrations. This collective converts the string's energy into audible waves, with the body's efficiency peaking at specific frequencies determined by its design. Two main types of resonance dominate the body's acoustic behavior: from the air cavity and plate modes from the wooden panels. arises from the enclosed air volume acting like a , where the f-holes serve as the "neck," typically resonating at frequencies around 100-350 Hz depending on instrument size, with violins around 250-350 Hz and cellos lower (around 100-200 Hz) to boost the fundamental tones of lower strings. In larger instruments like cellos, these resonances occur at lower frequencies (e.g., 100-250 Hz), increasing overlap with the playing range and wolf tone occurrence. Plate modes, visualized through Chladni patterns, represent the eigenvibrations of the top and back plates, with lower body modes (such as A0 for air-coupled plate motion and B1± for bending modes) occurring in the 100-600 Hz range, providing the instrument's characteristic warmth and projection. These modes collectively shape the , with the air and wood resonances interacting to amplify sound across the instrument's playing range without the strings alone producing sufficient volume. Several material and construction factors influence these resonances by altering the eigenfrequencies of the body. Wood density plays a key role, with lower-density (around 0.4 g/cm³ for the top plate) enabling lighter, more responsive vibrations compared to denser (0.5-0.7 g/cm³ for the back), affecting mode shapes and . Varnish application modifies surface and internal , potentially shifting frequencies by up to 5-10% depending on its composition and thickness, while glue joints ensure precise between components, with inconsistencies leading to uneven energy transfer. Overall , including plate thickness (e.g., 2.4-3.4 mm for violins, thicker for cellos around 3.5-4.5 mm), arching height, and rib curvature, governs distribution, directly impacting the distribution of resonant modes. The fundamental resonance frequency for plate vibrations can be approximated using the simple model, suitable for understanding basic eigenmodes before more complex analyses. The ff is given by f=12πkmf = \frac{1}{2\pi} \sqrt{\frac{k}{m}}
Add your contribution
Related Hubs
User Avatar
No comments yet.