Vibrato

At this point of technical development, current classically-trained string players use vibrato in every style and passage of music for better or worse. This constant application of vibrato became standard through the playing and teaching of great late nineteenth- and early twentieth-century artists like violinist Leopold Auer and cellist Pablo Casals. Today, the continuous vibrating of pitch by string players in Baroque- and Classical-era music produces romanticized renditions against which performance-practice advocates often shy away from in stylistic horror. What all of this means for anyone writing music for violin, viola, cello, or bass in these years preceding the new millennium is that they should expect string parts to be rendered with oscillations of pitch emulating the singing style of vocalists.

Before discussing the latest contemporary and radically new applications in vibrato, a more specific understanding of the traditional technique is warranted. First, vibrato is usually a uniform oscillating of pitch with two variables - speed and distance. Different combinations of an oscillation's speed and its distance produce a variety of sound colors. Johannes Brahms used in his music the Italian terms espressivo and dolce which, among other things, imply different kinds of vibrato. Generally, espressivo implies a vibrato oscillation that is relatively fast and narrow. On the other hand, dolce vibrato is executed relatively slowly and widely, for which such descriptive adjectives as sweet and warm apply. Another important basic concept to understand about vibrato is that it occurs only below the pitch. The human ear is very biased toward higher frequencies and hears the top crests as the true pitch rather than any median point in the middle of the oscillation waves.

These fundamental concepts are the basis of departure for more unique and contemporary vibrato techniques.
Now to the heart of the vibrant matter, the first major alternative to the omnipresence of oscillating string pitches which contemporary writers often use is to stipulate that the music be played without any vibrato whatsoever. This is communicated rhetorically at the beginning of a score or in performance notes, or with such expressions above the staff as senza vibrato or no vib if just a section, phrase, or even particular note is to sound as a white tone, straight without vibrato. To avoid confusion, if a player sees an indication above the staff to turn off vibrato, then that player needs to know when to turn it back on as communicated with some such expressions as con vibrato or vib. It is analogous to modern lighting - if one wishes to see in the dark again after the lights have been turned off, one must turn the switch on again.

To play a string instrument without vibrato causes a drastic change in tonal color. The Kronos Quartet uses no vibrato in much of their minimalist repertoire. The purity of harmonic intervals they create without vibrating produces one of the great, characteristic sounds of their ensemble. Also, many times vibrato is withheld in microtonal works where oscillating pitches would compromise the audible integrity of an alternative tuning. Likewise, in compositions where there are a lot of glissandi or sliding between and bending of pitches, vibrato is often not used because it tends to obscure the moving off of and onto true pitches.

As a point of moderation, composers are now sometimes asking for something called poco vibrato which strikes a medium between obvious oscillating pitch and stark, straight pitch. Poco vibrato is a discreet oscillation of the most narrow distance and of a not overly rapid speed. Of course, gradual changes from nonvibrato to poco vibrato to espressivo, sometimes called molto vibrato, and in the reverse order can be executed over the course of a passage or even within one note.

When oscillations are pushed beyond molto vibrato, string playing enters a radical land of instrumental techniques. All of these so-called extended vibrato techniques when they are used in a piece need a concise explanation of their execution in the work's performance notes. The term hypervibrato might well describe what happens when pitch oscillations become extraordinarily fast or wide. A super fast oscillation creates a tone reminiscent of a nanny goat's bray. Shaking the finger and hand an overly wide distance of a half step or even a whole step makes for a tone similar to the wah-wah effects in Jimi Hendrix's guitar playing. To indicate these, the writer can use the expression hypervibrato above the staff or use a graphic indication with the notes like Matthew Burrier does in II for solo cello. This graphic representation of the vibrato allows the player to follow the direction and contour suggested for the vibrato. The graphic squiggles and lines can then further introduce irregular vibrato oscillations and connect directly into and out of glissandos.

Matthew Burrier; II for solo cello

Lewis Nielson uses the interesting rhetorical expression grotesque vibrato in the cello part of Valentine Mechanique (Eating Carmen) for amplified cello and percussion. This indication removes the uniform quality of the oscillation and produces spasmodic sounds of unfocused pitches which in the context of Valentine Mechanique yields a somewhat humorous caricature effect.

Vibrato can also be added to a glissando by placing a rhetorical comment above the staff - vibrate while sliding between pitches. This makes for a truly wild and hairy projecting sonic highlight to the glissando.

Both traditional and radical vibratos are incorporated with other instrumental techniques. Vibrato is used when playing pizzicato (when the string is plucked or strummed with a finger). However, due to the decaying acoustic nature of a plucked string, vibrato applications tend to be somewhat less dramatic or acoustically obvious when played pizzicato as opposed to when played with a bow. Artificial harmonics can also be played with all the different types of vibrato. While it seems to be the general order of composers today for artificial or false harmonics to be rendered without vibrating, all one has to do is listen to a Paganini violin concerto and hear the singing quality imparted to false harmonics executed with vibrato to know the alternative. Usually it is left to the performerÕs discretion as to whether or not to oscillate on artificial harmonics. If a writer today definitely wishes to have artificial harmonics rendered with a singing quality or some other wild alternative oscillation as opposed to a straight tone that sounds somewhat like a pure sine wave, then a rhetorical expression such as con vibrato or molto vibrato should be used above the staff. For the natural harmonics on the open strings vibrato is hardly ever used. Its application on the overtone nodes of the open strings produces a phasing out of and into the focused pitch of the harmonic.

Extended vibrato techniques create new and incredibly unique voicing for stringed instrument lines. There remains more to discover about the sonic signatures vibrato imparts to a pitch, and it is important to remember that the oscillating parameters of speed and distance are what contemporary writers can manipulate to help customize the sounds of vibrating wires.